Using getopts to process long and short command line options

Question

I wish to have long and short forms of command line options invoked using my shell script   I know that getopts can be used  but like in Perl  I have not been able to do the same with shell   Any ideas on how this can be done  so that I can use options like     shell sh --copyfile abc pl  tmp    shell sh -c abc pl  tmp    In the above  both the commands mean the same thing to my shell  but using getopts  I have not been able to implement these

User · Answer

Another way       translate long options to short for arg do     delim        case   arg  in        --help  args    args -h            --verbose  args    args -v            --config  args    args -c              pass through anything else                 arg 0 1       -        delim                 args    args   delim   arg   delim          esac done   reset the translated args eval set --  args   now we can process with getopt while getopts   hvc   opt  do     case  opt in         h   usage            v   VERBOSE true            c   source  OPTARG                usage                       echo  option - OPTARG requires an argument          usage                esac done

User · Answer

Here s an example that actually uses getopt with long options   aflag no bflag no cargument none    options may be followed by one colon to indicate they have a required argument if   options   getopt -o abc  -l along blong clong  --       then       something went wrong  getopt will put out an error message for us     exit 1 fi  set --  options  while      -gt 0   do     case  1 in     -a --along  aflag  yes         -b --blong  bflag  yes           for options with required arguments  an additional shift is required     -c --clong  cargument   2    shift        --  shift  break        -   echo   0  error - unrecognized option  1  1 gt  amp 2  exit 1           break       esac     shift done

User · Answer

Inventing yet another version of the wheel     This function is a  hopefully  POSIX-compatible plain bourne shell replacement for GNU getopt  It supports short long options which can accept mandatory optional no arguments  and the way in which options are specified is almost identical to GNU getopt  so conversion is trivial   Of course this is still a sizeable chunk of code to drop into a script  but it s about half the lines of the well-known getopt long shell function  and might be preferable in cases where you just want to replace existing GNU getopt uses   This is pretty new code  so YMMV  and definitely please let me know if this isn t actually POSIX-compatible for any reason -- portability was the intention from the outset  but I don t have a useful POSIX test environment    Code and example usage follows      bin sh   posix getopt shell function   Author  Phil S    Version  1 0   Created  2016-07-05   URL  http   stackoverflow com a 37087374 324105    POSIX-compatible argument quoting and parameter save restore   http   www etalabs net sh tricks html   Usage    parameters   save         save the original parameters    eval  set --   parameters     restore the saved parameters  save          local param     for param  do         printf  s  n   param                  sed  s           g 1s        s                 done     printf  s  n          Exit with status  1 after displaying error message  2  exiterr          printf  s  n   2   gt  amp 2     exit  1      POSIX-compatible command line option parsing    This function supports long options and optional arguments  and is   a  largely-compatible  drop-in replacement for GNU getopt      Instead of    opts   getopt -o   shortopts  -l   longopts  --         eval set --   opts      We instead use    opts   posix getopt   shortopts    longopts          eval  set --   opts   posix getopt        args    shortopts    longopts           local shortopts longopts             arg argtype getopt nonopt opt optchar optword suffix      shortopts   1      longopts   2      shift 2      getopt      nonopt      while      -gt 0    do         opt          arg          argtype          case   1  in                --  means don t parse the remaining options               --                     getopt    getopt   save                        shift                    break                               process short option               -  -                 -x foo                  suffix   1 -       foo                 opt   1  suffix    -x                 optchar   opt -    x                 case    shortopts   in                          optchar           optional argument                         argtype optional                         arg    suffix                           shift                                                  optchar          required argument                         argtype required                         if   -n    suffix      then                             arg    suffix                               shift                         else                             case   2  in                                   -    exiterr 1   1 requires an argument                                           arg   2   shift 2                                          exiterr 1   1 requires an argument                                esac                         fi                                                  optchar         no argument                         argtype none                         arg                          shift                           Handle multiple no-argument parameters combined as                           -xyz instead of -x -y -z  If we have just shifted                           parameter -xyz  we now replace it with -yz  which                           will be processed in the next iteration                           if   -n    suffix      then                             eval  set --   save  -  suffix     save                                fi                                                   exiterr 1  Unknown option  1                    esac                               process long option               --                    --xarg  foo                  suffix   1          foo  unless there was no                    if      suffix       1     then                     suffix                  fi                 opt   1   suffix    --xarg                 optword   opt --    xarg                 case     longopts    in                           optword            optional argument                         argtype optional                         arg    suffix                           shift                                                   optword           required argument                         argtype required                         if   -n    suffix      then                             arg    suffix                               shift                         else                             case   2  in                                   -    exiterr 1                                           --  optword  requires an argument                                           arg   2   shift 2                                          exiterr 1                                           --  optword  requires an argument                                esac                         fi                                                   optword          no argument                         if   -n    suffix      then                             exiterr 1  --  optword  does not take an argument                          fi                         argtype none                         arg                          shift                                                   exiterr 1  Unknown option  1                    esac                               any other parameters starting with -               -    exiterr 1  Unknown option  1                  remember non-option parameters                   nonopt    nonopt   save   1     shift           esac          if   -n    opt      then             getopt    getopt   save   opt                case    argtype   in                   optional required                         getopt    getopt   save   arg                                    esac         fi     done        Generate function output  suitable for        eval  set --   posix getopt           printf  s    getopt       if   -n    nonopt      then         printf  s    save  --    nonopt       fi     Example usage     Process command line options shortopts  hvd c  s  L D  longopts  help version directory  client   server   load  delete   opts   getopt -o   shortopts  -l   longopts  -n    basename  0   --       opts   posix getopt   shortopts    longopts        if      -eq 0    then      eval set --   opts      eval  set --   opts       while      -gt 0    do         case   1  in               --                  shift  break                 -h --help           help 1  shift  break                 -v --version        version help 1  shift  break                 -d --directory      dir  2  shift 2                 -c --client         useclient 1  client  2  shift 2                 -s --server         startserver 1  server name  2  shift 2                 -L --load           load  2  shift 2                 -D --delete         delete 1  shift           esac     done else     shorthelp 1   getopt returned  and reported  an error  fi

User · Answer

I only write shell scripts now and then and fall out of practice  so any feedback is appreciated   Using the strategy proposed by  Arvid Requate  we noticed some user errors  A user who forgets to include a value will accidentally have the next option s name treated as a value     getopts test sh --loglevel  --toc TRUE   will cause the value of  loglevel  to be seen as  --toc TRUE   This can be avoided   I adapted some ideas about checking user error for CLI from  http   mwiki wooledge org BashFAQ 035 discussion of manual parsing  I inserted error checking into handling both  -  and  --  arguments    Then I started fiddling around with the syntax  so any errors in here are strictly my fault  not the original authors    My approach helps users who prefer to enter long with or without the equal sign  That is  it should have same response to  --loglevel 9  as  --loglevel 9   In the -- space method  it is not possible to know for sure if the user forgets an argument  so some guessing is needed     if the user has the long equal sign format  --opt    then a space after   triggers an error because an argument was not supplied    if user has long space arguments  --opt    this script causes a fail if no argument follows  end of command  or if argument begins with dash    In case you are starting out on this  there is an interesting difference between  --opt value  and  --opt value  formats  With the equal sign  the command line argument is seen as  opt value  and the work to handle that is string parsing  to separate at the       In contrast  with  --opt value   the name of the argument is  opt  and we have the challenge of getting the next value supplied in the command line   That s where  Arvid Requate used    OPTIND   the indirect reference  I still don t understand that  well  at all  and comments in BashFAQ seem to warn against that style  http   mywiki wooledge org BashFAQ 006   BTW  I don t think previous poster s comments about importance of  OPTIND      OPTIND   1    are correct  I mean to say  I see no harm from omitting it   In newest version of this script  flag -v means VERBOSE printout    Save it in a file called  cli-5 sh   make executable  and any of these will work  or fail in the desired way    cli-5 sh  -v --loglevel 44 --toc  TRUE   cli-5 sh  -v --loglevel 44 --toc TRUE   cli-5 sh --loglevel 7   cli-5 sh --loglevel 8   cli-5 sh -l9    cli-5 sh  --toc FALSE --loglevel 77   cli-5 sh  --toc FALSE --loglevel 77    cli-5 sh   -l99 -t yyy   cli-5 sh   -l 99 -t yyy   Here is example output of the error-checking on user intpu      cli-5 sh  --toc --loglevel 77 ERROR  toc value must not have dash at beginning     cli-5 sh  --toc  --loglevel 77 ERROR  value for toc undefined   You should consider turning on -v  because it prints out internals of OPTIND and OPTARG    usr bin env bash     Paul Johnson    20171016        Combines ideas from    https   stackoverflow com questions 402377 using-getopts-in-bash-shell-script-to-get-long-and-short-command-line-options    by  Arvid Requate  and http   mwiki wooledge org BashFAQ 035    What I don t understand yet     In  Arvid REquate s answer  we have    val     OPTIND    OPTIND      OPTIND   1      this works  but I don t understand it    die         printf   s n    1   gt  amp 2     exit 1    printparse        if     VERBOSE  -gt 0    then         printf  Parse   s s s n    1    2    3   gt  amp 2      fi    showme        if     VERBOSE  -gt 0    then         printf  VERBOSE   s n    1   gt  amp 2      fi     VERBOSE 0 loglevel 0 toc  TRUE   optspec   vhl t -   while getopts   optspec  OPTCHAR  do      showme  OPTARG     OPTARG          showme  OPTIND     OPTIND          case    OPTCHAR   in         -              case    OPTARG   in                 loglevel   argument has no equal sign                     opt   OPTARG                      val     OPTIND                          check value  If negative  assume user forgot value                     showme  OPTIND is   OPTIND    OPTIND  has value      OPTIND                         if      val     -      then                         die  ERROR   opt value must not have dash at beginning                      fi                        OPTIND      OPTIND   1      CAUTION  no effect                      printparse  --  OPTARG           val                       loglevel    val                       shift                                        loglevel     argument has equal sign                     opt   OPTARG                         val   OPTARG                         if      OPTARG         then                         printparse  --  opt          val                           loglevel    val                              shift CAUTION don t shift this  fails othewise                     else                         die  ERROR   opt value must be supplied                      fi                                        toc   argument has no equal sign                     opt   OPTARG                      val     OPTIND                          check value  If negative  assume user forgot value                     showme  OPTIND is   OPTIND    OPTIND  has value      OPTIND                         if      val     -      then                         die  ERROR   opt value must not have dash at beginning                      fi                        OPTIND      OPTIND   1                            printparse  --  opt          val                       toc    val                       shift                                        toc     argument has equal sign                     opt   OPTARG                         val   OPTARG                         if      OPTARG         then                         toc   val                          printparse  -- opt    - gt      toc                            shift    NO  dont shift this                     else                         die  ERROR  value for  opt undefined                      fi                                         help                      echo  usage   0  -v   --loglevel    lt value gt    --toc    lt TRUE FALSE gt     gt  amp 2                     exit 2                                                               if     OPTERR    1    amp  amp       optspec 0 1             then                         echo  Unknown option --  OPTARG    gt  amp 2                     fi                                    esac           h -   --help                 must rewrite this for all of the arguments             echo  usage   0  -v   --loglevel    lt value gt    --toc    lt TRUE FALSE gt     gt  amp 2             exit 2                        l              loglevel   OPTARG              printparse  -l          loglevel                          t              toc   OPTARG                         v              VERBOSE 1                                        if     OPTERR     1           optspec 0 1            then                 echo  Non-option argument   -  OPTARG     gt  amp 2             fi                    esac done    echo   After Parsing values   echo  loglevel   loglevel   echo  toc   toc

User · Answer

The built-in getopts can t do this   There is an external getopt 1  program that can do this  but you only get it on Linux from the util-linux package  It comes with an example script getopt-parse bash   There is also a getopts long written as a shell function

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Take a look at shFlags which is a portable shell library  meaning  sh  bash  dash  ksh  zsh on Linux  Solaris  etc     It makes adding new flags as simple as adding one line to your script  and it provides an auto generated usage function   Here is a simple Hello  world  using shFlag      bin sh    source shflags from current directory     shflags    define a  name  command-line string flag DEFINE string  name   world   name to say hello to   n     parse the command-line FLAGS         exit 1 eval set --    FLAGS ARGV      say hello echo  Hello    FLAGS name      For OSes that have the enhanced getopt that supports long options  e g  Linux   you can do       hello world sh --name Kate Hello  Kate    For the rest  you must use the short option       hello world sh -n Kate Hello  Kate    Adding a new flag is as simple as adding a new DEFINE  call

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I wanted something without external dependencies  with strict bash support  -u   and I needed it to work on even the older bash versions  This handles various types of params    short bools  -h   short options  -i  image jpg    long bools  --help  equals options  --file  filename ext   space options  --file  filename ext   concatinated bools  -hvm    Just insert the following at the top of your script     Check if a list of params contains a specific param   usage  if  param variant  h   help p path f file long-thing t test-thing   file    then       the global variable  key is updated to the long notation  last entry in the pipe delineated list  if applicable   param variant       for param in  1   do     local variants   param            for variant in  variants   do       if      variant      2       then           Update the key to match the long version         local arr    param                 let last    arr    -1         key    arr  last            return 0       fi     done   done   return 1      Get input parameters in short or long notation  with no dependencies beyond bash   usage          First  set your defaults       param help false       param path           param file false       param image false       param image lossy true         Define allowed parameters       allowed params  h   help p path f file i image image-lossy          Get parameters from the arguments provided        get params        Parameters will be converted into safe variable names like        param help        param path        param file        param image        param image lossy     Parameters without a value like  -h  or  --help  will be treated as   boolean  and will be set as param help true     Parameters can accept values in the various typical ways        -i  path goes here        --image  path goes here        --image  path goes here        --image path goes here   These would all result in effectively the same thing        param image  path goes here      Concatinated short parameters  boolean  are also supported       -vhm is the same as -v -h -m  get params       local param pair   local key   local value   local shift count    while     do       Ensure we have a valid param  Allows this to work even in -u mode      if          0    -z  1      then       break     fi        Split the argument if it contains         param pair    1              Remove preceeding dashes     key    param pair 0  --          Check for concatinated boolean short parameters      local nodash    key -       local breakout false     if      nodash       key   amp  amp     nodash  -gt 1     then         Extrapolate multiple boolean keys in single dash notation  ie   -vmh  should translate to   -v -m -h        local short param count    nodash        let new arg count     short param count-1       local new args             str pos is the current position in the short param string  nodash       for    str pos 0  str pos lt new arg count  str pos       do           The first character becomes the current key         if    str pos -eq 0     then           key    nodash  str pos 1             breakout true         fi            arg pos is the current position in the constructed arguments list         let arg pos  str pos 1         if    arg pos -gt  short param count     then             handle other arguments           let orignal arg number  arg pos- short param count 1           local new arg     orignal arg number           else             break out our one argument into new ones           local new arg  -  nodash  str pos 1           fi         new args   new args    new arg          done         remove the preceding space and set the new arguments       eval set --    new args         fi     if    breakout   then       key   nodash      fi        By default we expect to shift one argument at a time     shift count 1     if       param pair      -gt  1      then         This is a param with equals notation       value    param pair 1        else         This is either a boolean param and there is no value          or the value is the next command line argument         Assume the value is a boolean true  unless the next argument is found to be a value        value true       if       -gt 1  amp  amp  -n   2      then         local nodash    2 -           if     nodash      2     then             The next argument has NO preceding dash so it is a value           value   2            shift count 2         fi       fi     fi        Check that the param being passed is one of the allowed params     if  param variant   allowed params    key    then         --key-name will now become param key name       eval param   key  -      value      else       printf  WARNING  Unknown option  ignored    s n    1   gt  amp 2     fi     shift  shift count   done     And use it like so     Assign defaults for parameters param help false param path   pwd  param file false param image true param image lossy true param image lossy quality 85    Define the params we will allow allowed params  h   help p path f file i image image-lossy image-lossy-quality     Get the params from arguments provided  get params

User · Answer

getopt and getopts are different beasts  and people seem to have a bit of misunderstanding of what they do   getopts is a built-in command to bash to process command-line options in a loop and assign each found option and value in turn to built-in variables  so you can further process them   getopt  however  is an external utility program  and it doesn t actually process your options for you the way that e g  bash getopts  the Perl Getopt module or the Python optparse argparse modules do   All that getopt does is canonicalize the options that are passed in     i e  convert them to a more standard form  so that it s easier for a shell script to process them   For example  an application of getopt might convert the following   myscript -ab infile txt -ooutfile txt   into this   myscript -a -b -o outfile txt infile txt   You have to do the actual processing yourself   You don t have to use getopt at all if you make various restrictions on the way you can specify options     only put one option per argument   all options go before any positional parameters  i e  non-option arguments   for options with values  e g  -o above   the value has to go as a separate argument  after a space     Why use getopt instead of getopts   The basic reason is that only GNU getopt gives you support for long-named command-line options 1  GNU getopt is the default on Linux  Mac OS X and FreeBSD come with a basic and not-very-useful getopt  but the GNU version can be installed  see below    For example  here s an example of using GNU getopt  from a script of mine called javawrap     NOTE  This requires GNU getopt   On Mac OS X and FreeBSD  you have to install this   separately  see below  TEMP  getopt -o vdm  --long verbose debug memory  debugfile  minheap  maxheap                 -n  javawrap  --        if         0     then echo  Terminating      gt  amp 2   exit 1   fi    Note the quotes around   TEMP   they are essential  eval set --   TEMP   VERBOSE false DEBUG false MEMORY  DEBUGFILE  JAVA MISC OPT  while true  do   case   1  in     -v   --verbose   VERBOSE true  shift        -d   --debug   DEBUG true  shift        -m   --memory   MEMORY   2   shift 2        --debugfile   DEBUGFILE   2   shift 2        --minheap         JAVA MISC OPT   JAVA MISC OPT -XX MinHeapFreeRatio  2   shift 2        --maxheap         JAVA MISC OPT   JAVA MISC OPT -XX MaxHeapFreeRatio  2   shift 2        --   shift  break            break      esac done   This lets you specify options like --verbose -dm4096 --minh 20 --maxhe 40 --debugfi   Users John Johnson debug txt  or similar   The effect of the call to getopt is to canonicalize the options to --verbose -d -m 4096 --minheap 20 --maxheap 40 --debugfile   Users John Johnson debug txt  so that you can more easily process them   The quoting around   1  and   2  is important as it ensures that arguments with spaces in them get handled properly   If you delete the first 9 lines  everything up through the eval set line   the code will still work   However  your code will be much pickier in what sorts of options it accepts  In particular  you ll have to specify all options in the  canonical  form described above   With the use of getopt  however  you can group single-letter options  use shorter non-ambiguous forms of long-options  use either the --file foo txt or --file foo txt style  use either the -m 4096 or -m4096 style  mix options and non-options in any order  etc   getopt also outputs an error message if unrecognized or ambiguous options are found   NOTE  There are actually two totally different versions of getopt  basic getopt and GNU getopt  with different features and different calling conventions 2 Basic getopt is quite broken  Not only does it not handle long options  it also can t even handle embedded spaces inside of arguments or empty arguments  whereas getopts does do this right  The above code will not work in basic getopt  GNU getopt is installed by default on Linux  but on Mac OS X and FreeBSD it needs to be installed separately  On Mac OS X  install MacPorts  http   www macports org  and then do sudo port install getopt to install GNU getopt  usually into  opt local bin   and make sure that  opt local bin is in your shell path ahead of  usr bin  On FreeBSD  install misc getopt   A quick guide to modifying the example code for your own program  Of the first few lines  all is  boilerplate  that should stay the same  except the line that calls getopt   You should change the program name after -n  specify short options after -o  and long options after --long   Put a colon after options that take a value   Finally  if you see code that has just set instead of eval set  it was written for BSD getopt  You should change it to use the eval set style  which works fine with both versions of getopt  while the plain set doesn t work right with GNU getopt   1Actually  getopts in ksh93 supports long-named options  but this shell isn t used as often as bash  In zsh  use zparseopts to get this functionality   2Technically   GNU getopt  is a misnomer  this version was actually written for Linux rather than the GNU project  However  it follows all the GNU conventions  and the term  GNU getopt  is commonly used  e g  on FreeBSD

User · Answer

A simple DIY to get only long named args   Use       test-args sh --a1 a1 --a2  a 2  --a3 --a4  --a5 a5 --a6  a 6  a1    a1  a2    a 2  a3    TRUE  a4      a5    a5  a6    a 6  a7        Script      bin bash  function main         ARGS  getArgs            a1  echo   ARGS    getNamedArg a1      a2  echo   ARGS    getNamedArg a2      a3  echo   ARGS    getNamedArg a3      a4  echo   ARGS    getNamedArg a4      a5  echo   ARGS    getNamedArg a5      a6  echo   ARGS    getNamedArg a6      a7  echo   ARGS    getNamedArg a7       echo  a1      a1        echo  a2      a2        echo  a3      a3        echo  a4      a4        echo  a5      a5        echo  a6      a6        echo  a7      a7         exit 0     function getArgs         for arg in       do         echo   arg      done     function getNamedArg         ARG NAME  1      sed --regexp-extended --quiet --expression           s  -- ARG NAME         1 p    Get arguments in format  --arg value    s ubstitute  --arg value  by  value   and  p rint           -- ARG NAME                 Get arguments in format  --arg value  ou  --arg              n                         -  n ext  because in this format  if value exists  it will be the next argument               --   p                  - If next doesn t starts with  --   it is the value of the actual argument               --                      - If next do starts with  --   it is the next argument and the actual argument is a boolean one                   Then just repla c ed by TRUE                 c TRUE                                   main

User · Answer

The built-in getopts command is still  AFAIK  limited to single-character options only   There is  or used to be  an external program getopt that would reorganize a set of options such that it was easier to parse   You could adapt that design to handle long options too   Example usage   aflag no bflag no flist    set --   getopt abf        while      -gt 0   do     case   1  in      -a  aflag yes        -b  bflag yes        -f  flist   flist  2   shift        --  shift  break        -   echo   0  error - unrecognized option  1  1 gt  amp 2  exit 1            break       esac     shift done    Process remaining non-option arguments       You could use a similar scheme with a getoptlong command   Note that the fundamental weakness with the external getopt program is the difficulty of handling arguments with spaces in them  and in preserving those spaces accurately   This is why the built-in getopts is superior  albeit limited by the fact it only handles single-letter options

User · Answer

I have been working on that subject for quite a long time    and made my own library which you will need to source in your main script  See libopt4shell and cd2mpc for an example  Hope it helps

User · Answer

I kind of solved this way     A string with command options options       An array with all the arguments arguments   options     Loop index index 0  for argument in  options   do       Incrementing index     index  expr  index   1         The conditions     case  argument in       -a  echo  key  argument value   arguments index             -abc  echo  key  argument value   arguments index           esac   done  exit    Am I being dumb or something  getopt and getopts are so confusing

User · Answer

Maybe it s simpler to use ksh  just for the getopts part  if need long command line options  as it can be easier done there     Working Getopts Long   gt  KSH      bin ksh   Getopts Long USAGE  s showconfig   USAGE   c  createdb   USAGE   l  createlistener   USAGE   g  generatescripts   USAGE   r  removedb   USAGE   x  removelistener   USAGE   t  createtemplate   USAGE   h help    while getopts   USAGE  optchar   do     case  optchar in     s   echo  Displaying Configuration             c   echo  Creating Database  OPTARG         l   echo  Creating Listener LISTENER  OPTARG         g   echo  Generating Scripts for Database  OPTARG         r   echo  Removing Database  OPTARG         x   echo  Removing Listener LISTENER  OPTARG         t   echo  Creating Database Template         h   echo  Help         esac done

User · Answer

Here you can find a few different approaches for complex option parsing in bash  http   mywiki wooledge org ComplexOptionParsing  I did create the following one  and I think it s a good one  because it s minimal code and both long and short options work  A long option can also have multiple arguments with this approach      bin bash   Uses bash extensions   Not portable as written   declare -A longoptspec longoptspec    loglevel  1    use associative array to declare how many arguments a long option expects  in this case we declare that loglevel expects has one argument  long options that aren t listed i n this way will have zero arguments by default optspec   h-   while getopts   optspec  opt  do while true  do     case    opt   in         -   OPTARG is name-of-long-option or name-of-long-option value             if       OPTARG                with this --key value format only one argument is possible             then                 opt   OPTARG                      OPTARG   OPTARG                       OPTIND--                   else  with this --key value1 value2 format multiple arguments are possible                 opt   OPTARG                  OPTARG      OPTIND    longoptspec  opt                  fi               OPTIND  longoptspec  opt                continue  now that opt OPTARG are set we can process them as if getopts would ve given us long options                        loglevel            loglevel  OPTARG                        h help              echo  usage   0  --loglevel    lt value gt     gt  amp 2             exit 2                    esac break  done done    End of file

User · Answer

I have been working on that subject for quite a long time    and made my own library which you will need to source in your main script  See libopt4shell and cd2mpc for an example  Hope it helps

User · Answer

getopt and getopts are different beasts  and people seem to have a bit of misunderstanding of what they do   getopts is a built-in command to bash to process command-line options in a loop and assign each found option and value in turn to built-in variables  so you can further process them   getopt  however  is an external utility program  and it doesn t actually process your options for you the way that e g  bash getopts  the Perl Getopt module or the Python optparse argparse modules do   All that getopt does is canonicalize the options that are passed in     i e  convert them to a more standard form  so that it s easier for a shell script to process them   For example  an application of getopt might convert the following   myscript -ab infile txt -ooutfile txt   into this   myscript -a -b -o outfile txt infile txt   You have to do the actual processing yourself   You don t have to use getopt at all if you make various restrictions on the way you can specify options     only put one option per argument   all options go before any positional parameters  i e  non-option arguments   for options with values  e g  -o above   the value has to go as a separate argument  after a space     Why use getopt instead of getopts   The basic reason is that only GNU getopt gives you support for long-named command-line options 1  GNU getopt is the default on Linux  Mac OS X and FreeBSD come with a basic and not-very-useful getopt  but the GNU version can be installed  see below    For example  here s an example of using GNU getopt  from a script of mine called javawrap     NOTE  This requires GNU getopt   On Mac OS X and FreeBSD  you have to install this   separately  see below  TEMP  getopt -o vdm  --long verbose debug memory  debugfile  minheap  maxheap                 -n  javawrap  --        if         0     then echo  Terminating      gt  amp 2   exit 1   fi    Note the quotes around   TEMP   they are essential  eval set --   TEMP   VERBOSE false DEBUG false MEMORY  DEBUGFILE  JAVA MISC OPT  while true  do   case   1  in     -v   --verbose   VERBOSE true  shift        -d   --debug   DEBUG true  shift        -m   --memory   MEMORY   2   shift 2        --debugfile   DEBUGFILE   2   shift 2        --minheap         JAVA MISC OPT   JAVA MISC OPT -XX MinHeapFreeRatio  2   shift 2        --maxheap         JAVA MISC OPT   JAVA MISC OPT -XX MaxHeapFreeRatio  2   shift 2        --   shift  break            break      esac done   This lets you specify options like --verbose -dm4096 --minh 20 --maxhe 40 --debugfi   Users John Johnson debug txt  or similar   The effect of the call to getopt is to canonicalize the options to --verbose -d -m 4096 --minheap 20 --maxheap 40 --debugfile   Users John Johnson debug txt  so that you can more easily process them   The quoting around   1  and   2  is important as it ensures that arguments with spaces in them get handled properly   If you delete the first 9 lines  everything up through the eval set line   the code will still work   However  your code will be much pickier in what sorts of options it accepts  In particular  you ll have to specify all options in the  canonical  form described above   With the use of getopt  however  you can group single-letter options  use shorter non-ambiguous forms of long-options  use either the --file foo txt or --file foo txt style  use either the -m 4096 or -m4096 style  mix options and non-options in any order  etc   getopt also outputs an error message if unrecognized or ambiguous options are found   NOTE  There are actually two totally different versions of getopt  basic getopt and GNU getopt  with different features and different calling conventions 2 Basic getopt is quite broken  Not only does it not handle long options  it also can t even handle embedded spaces inside of arguments or empty arguments  whereas getopts does do this right  The above code will not work in basic getopt  GNU getopt is installed by default on Linux  but on Mac OS X and FreeBSD it needs to be installed separately  On Mac OS X  install MacPorts  http   www macports org  and then do sudo port install getopt to install GNU getopt  usually into  opt local bin   and make sure that  opt local bin is in your shell path ahead of  usr bin  On FreeBSD  install misc getopt   A quick guide to modifying the example code for your own program  Of the first few lines  all is  boilerplate  that should stay the same  except the line that calls getopt   You should change the program name after -n  specify short options after -o  and long options after --long   Put a colon after options that take a value   Finally  if you see code that has just set instead of eval set  it was written for BSD getopt  You should change it to use the eval set style  which works fine with both versions of getopt  while the plain set doesn t work right with GNU getopt   1Actually  getopts in ksh93 supports long-named options  but this shell isn t used as often as bash  In zsh  use zparseopts to get this functionality   2Technically   GNU getopt  is a misnomer  this version was actually written for Linux rather than the GNU project  However  it follows all the GNU conventions  and the term  GNU getopt  is commonly used  e g  on FreeBSD

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A simple DIY to get only long named args   Use       test-args sh --a1 a1 --a2  a 2  --a3 --a4  --a5 a5 --a6  a 6  a1    a1  a2    a 2  a3    TRUE  a4      a5    a5  a6    a 6  a7        Script      bin bash  function main         ARGS  getArgs            a1  echo   ARGS    getNamedArg a1      a2  echo   ARGS    getNamedArg a2      a3  echo   ARGS    getNamedArg a3      a4  echo   ARGS    getNamedArg a4      a5  echo   ARGS    getNamedArg a5      a6  echo   ARGS    getNamedArg a6      a7  echo   ARGS    getNamedArg a7       echo  a1      a1        echo  a2      a2        echo  a3      a3        echo  a4      a4        echo  a5      a5        echo  a6      a6        echo  a7      a7         exit 0     function getArgs         for arg in       do         echo   arg      done     function getNamedArg         ARG NAME  1      sed --regexp-extended --quiet --expression           s  -- ARG NAME         1 p    Get arguments in format  --arg value    s ubstitute  --arg value  by  value   and  p rint           -- ARG NAME                 Get arguments in format  --arg value  ou  --arg              n                         -  n ext  because in this format  if value exists  it will be the next argument               --   p                  - If next doesn t starts with  --   it is the value of the actual argument               --                      - If next do starts with  --   it is the next argument and the actual argument is a boolean one                   Then just repla c ed by TRUE                 c TRUE                                   main

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There are three implementations that may be considered    Bash builtin getopts  This does not support long option names with the double-dash prefix   It only supports single-character options  BSD UNIX implementation of standalone getopt command  which is what MacOS uses   This does not support long options either  GNU implementation of standalone getopt   GNU getopt 3   used by the command-line getopt 1  on Linux  supports parsing long options        Some other answers show a solution for using the bash builtin getopts to mimic long options  That solution actually makes a short option whose character is  -   So you get  --  as the flag  Then anything following that becomes OPTARG  and you test the OPTARG with a nested case   This is clever  but it comes with caveats     getopts can t enforce the opt spec  It can t return errors if the user supplies an invalid option  You have to do your own error-checking as you parse OPTARG  OPTARG is used for the long option name  which complicates usage when your long option itself has an argument  You end up having to code that yourself as an additional case    So while it is possible to write more code to work around the lack of support for long options  this is a lot more work and partially defeats the purpose of using a getopt parser to simplify your code

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I kind of solved this way     A string with command options options       An array with all the arguments arguments   options     Loop index index 0  for argument in  options   do       Incrementing index     index  expr  index   1         The conditions     case  argument in       -a  echo  key  argument value   arguments index             -abc  echo  key  argument value   arguments index           esac   done  exit    Am I being dumb or something  getopt and getopts are so confusing

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Th built-in OS X  BSD  getopt does not support long options  but the GNU version does  brew install gnu-getopt   Then  something similar to  cp  usr local Cellar gnu-getopt 1 1 6 bin getopt  usr local bin gnu-getopt

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The built-in getopts can t do this   There is an external getopt 1  program that can do this  but you only get it on Linux from the util-linux package  It comes with an example script getopt-parse bash   There is also a getopts long written as a shell function

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hm   not really satisfied with the pure bash options  why not use perl to get what you want  Directly parse the    array  and auto-name your options   simple helper script      usr bin perl use Getopt  Long   my  optstring   shift   my  opts   split m      optstring    my  opt  GetOptions   opt   opts    print  set --     join      map          ARGV          my  xx   my  key  foreach  key  keys  opt         print  export  key   opt  key           then you can use in your script as a one liner  for example      bin bash  eval  getopts pl reuse s long opt s hello       echo  HELLO   hello  echo  LONG OPT   long opt  echo  REUSE   reuse   echo       tmp script sh hello --reuse me --long opt whatever you want except spaces --hello 1 2 3  HELLO  1 LONG OPT  whatever you want except spaces REUSE  me  1 2 3  Only caveat here is spaces don t work  But it avoids bash s rather complicated looping syntax  works with long args  auto-names them as variables and automatically resizes     so will work 99  of the time

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The built-in getopts command is still  AFAIK  limited to single-character options only   There is  or used to be  an external program getopt that would reorganize a set of options such that it was easier to parse   You could adapt that design to handle long options too   Example usage   aflag no bflag no flist    set --   getopt abf        while      -gt 0   do     case   1  in      -a  aflag yes        -b  bflag yes        -f  flist   flist  2   shift        --  shift  break        -   echo   0  error - unrecognized option  1  1 gt  amp 2  exit 1            break       esac     shift done    Process remaining non-option arguments       You could use a similar scheme with a getoptlong command   Note that the fundamental weakness with the external getopt program is the difficulty of handling arguments with spaces in them  and in preserving those spaces accurately   This is why the built-in getopts is superior  albeit limited by the fact it only handles single-letter options

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Th built-in OS X  BSD  getopt does not support long options  but the GNU version does  brew install gnu-getopt   Then  something similar to  cp  usr local Cellar gnu-getopt 1 1 6 bin getopt  usr local bin gnu-getopt

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The built-in getopts command is still  AFAIK  limited to single-character options only   There is  or used to be  an external program getopt that would reorganize a set of options such that it was easier to parse   You could adapt that design to handle long options too   Example usage   aflag no bflag no flist    set --   getopt abf        while      -gt 0   do     case   1  in      -a  aflag yes        -b  bflag yes        -f  flist   flist  2   shift        --  shift  break        -   echo   0  error - unrecognized option  1  1 gt  amp 2  exit 1            break       esac     shift done    Process remaining non-option arguments       You could use a similar scheme with a getoptlong command   Note that the fundamental weakness with the external getopt program is the difficulty of handling arguments with spaces in them  and in preserving those spaces accurately   This is why the built-in getopts is superior  albeit limited by the fact it only handles single-letter options

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Here you can find a few different approaches for complex option parsing in bash  http   mywiki wooledge org ComplexOptionParsing  I did create the following one  and I think it s a good one  because it s minimal code and both long and short options work  A long option can also have multiple arguments with this approach      bin bash   Uses bash extensions   Not portable as written   declare -A longoptspec longoptspec    loglevel  1    use associative array to declare how many arguments a long option expects  in this case we declare that loglevel expects has one argument  long options that aren t listed i n this way will have zero arguments by default optspec   h-   while getopts   optspec  opt  do while true  do     case    opt   in         -   OPTARG is name-of-long-option or name-of-long-option value             if       OPTARG                with this --key value format only one argument is possible             then                 opt   OPTARG                      OPTARG   OPTARG                       OPTIND--                   else  with this --key value1 value2 format multiple arguments are possible                 opt   OPTARG                  OPTARG      OPTIND    longoptspec  opt                  fi               OPTIND  longoptspec  opt                continue  now that opt OPTARG are set we can process them as if getopts would ve given us long options                        loglevel            loglevel  OPTARG                        h help              echo  usage   0  --loglevel    lt value gt     gt  amp 2             exit 2                    esac break  done done    End of file

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The built-in getopts can t do this   There is an external getopt 1  program that can do this  but you only get it on Linux from the util-linux package  It comes with an example script getopt-parse bash   There is also a getopts long written as a shell function

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The Bash builtin getopts function can be used to parse long options by putting a dash character followed by a colon into the optspec      usr bin env bash  optspec   hv-   while getopts   optspec  optchar  do     case    optchar   in         -              case    OPTARG   in                 loglevel                      val     OPTIND    OPTIND      OPTIND   1                        echo  Parsing option   --  OPTARG    value     val     gt  amp 2                                         loglevel                        val   OPTARG                         opt   OPTARG   val                      echo  Parsing option   --  opt    value     val     gt  amp 2                                                               if     OPTERR    1    amp  amp       optspec 0 1             then                         echo  Unknown option --  OPTARG    gt  amp 2                     fi                                    esac           h              echo  usage   0  -v   --loglevel    lt value gt     gt  amp 2             exit 2                        v              echo  Parsing option   -  optchar     gt  amp 2                                       if     OPTERR     1           optspec 0 1            then                 echo  Non-option argument   -  OPTARG     gt  amp 2             fi                    esac done   After copying to executable file name getopts test sh in the current working directory  one can produce output like      getopts test sh     getopts test sh -f Non-option argument   -f      getopts test sh -h usage  code getopts test sh  -v   --loglevel    lt value gt       getopts test sh --help     getopts test sh -v Parsing option   -v      getopts test sh --very-bad     getopts test sh --loglevel Parsing option   --loglevel   value         getopts test sh --loglevel 11 Parsing option   --loglevel   value   11      getopts test sh --loglevel 11 Parsing option   --loglevel   value   11    Obviously getopts neither performs OPTERR checking nor option-argument parsing for the long options  The script fragment above shows how this may be done manually  The basic principle also works in the Debian Almquist shell   dash    Note the special case   getopts --  -       without the option terminator  --   bash complains about  -   getopts  -          this works in the Debian Almquist shell   dash     Note that  as GreyCat from over at http   mywiki wooledge org BashFAQ points out  this trick exploits a non-standard behaviour of the shell which permits the option-argument  i e  the filename in  -f filename   to be concatenated to the option  as in  -ffilename    The POSIX standard says there must be a space between them  which in the case of  -- longoption  would terminate the option-parsing and turn all longoptions into non-option arguments

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The accepted answer does a very nice job of pointing out all the shortcomings of bash built-in getopts  The answer ends with      So while it is possible to write more code to work around the lack of support for long options  this is a lot more work and partially defeats the purpose of using a getopt parser to simplify your code    And even though I agree in principle with that statement  I feel that the number of times we all implemented this feature in various scripts justifies putting a bit of effort into creating a  standardised   well tested solution   As such  I ve  upgraded  bash built in getopts by implementing getopts long in pure bash  with no external dependencies  The usage of the function is 100  compatible  with the built-in getopts   By including getopts long  which is hosted on GitHub  in a script  the answer to the original question can be implemented as simply as   source    PATH TO  getopts long bash   while getopts long   c  copyfile   OPTKEY  do     case   OPTKEY  in          c   copyfile               echo  file supplied --   OPTARG                                           echo  INVALID OPTION --   OPTARG    gt  amp 2             exit 1                                         echo  MISSING ARGUMENT for option --   OPTARG    gt  amp 2             exit 1                                       echo  Misconfigured OPTSPEC or uncaught option --   OPTKEY    gt  amp 2             exit 1                    esac done  shift     OPTIND - 1          1       --      amp  amp  shift

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Here s an example that actually uses getopt with long options   aflag no bflag no cargument none    options may be followed by one colon to indicate they have a required argument if   options   getopt -o abc  -l along blong clong  --       then       something went wrong  getopt will put out an error message for us     exit 1 fi  set --  options  while      -gt 0   do     case  1 in     -a --along  aflag  yes         -b --blong  bflag  yes           for options with required arguments  an additional shift is required     -c --clong  cargument   2    shift        --  shift  break        -   echo   0  error - unrecognized option  1  1 gt  amp 2  exit 1           break       esac     shift done

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The built-in getopts can t do this   There is an external getopt 1  program that can do this  but you only get it on Linux from the util-linux package  It comes with an example script getopt-parse bash   There is also a getopts long written as a shell function

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I wanted something without external dependencies  with strict bash support  -u   and I needed it to work on even the older bash versions  This handles various types of params    short bools  -h   short options  -i  image jpg    long bools  --help  equals options  --file  filename ext   space options  --file  filename ext   concatinated bools  -hvm    Just insert the following at the top of your script     Check if a list of params contains a specific param   usage  if  param variant  h   help p path f file long-thing t test-thing   file    then       the global variable  key is updated to the long notation  last entry in the pipe delineated list  if applicable   param variant       for param in  1   do     local variants   param            for variant in  variants   do       if      variant      2       then           Update the key to match the long version         local arr    param                 let last    arr    -1         key    arr  last            return 0       fi     done   done   return 1      Get input parameters in short or long notation  with no dependencies beyond bash   usage          First  set your defaults       param help false       param path           param file false       param image false       param image lossy true         Define allowed parameters       allowed params  h   help p path f file i image image-lossy          Get parameters from the arguments provided        get params        Parameters will be converted into safe variable names like        param help        param path        param file        param image        param image lossy     Parameters without a value like  -h  or  --help  will be treated as   boolean  and will be set as param help true     Parameters can accept values in the various typical ways        -i  path goes here        --image  path goes here        --image  path goes here        --image path goes here   These would all result in effectively the same thing        param image  path goes here      Concatinated short parameters  boolean  are also supported       -vhm is the same as -v -h -m  get params       local param pair   local key   local value   local shift count    while     do       Ensure we have a valid param  Allows this to work even in -u mode      if          0    -z  1      then       break     fi        Split the argument if it contains         param pair    1              Remove preceeding dashes     key    param pair 0  --          Check for concatinated boolean short parameters      local nodash    key -       local breakout false     if      nodash       key   amp  amp     nodash  -gt 1     then         Extrapolate multiple boolean keys in single dash notation  ie   -vmh  should translate to   -v -m -h        local short param count    nodash        let new arg count     short param count-1       local new args             str pos is the current position in the short param string  nodash       for    str pos 0  str pos lt new arg count  str pos       do           The first character becomes the current key         if    str pos -eq 0     then           key    nodash  str pos 1             breakout true         fi            arg pos is the current position in the constructed arguments list         let arg pos  str pos 1         if    arg pos -gt  short param count     then             handle other arguments           let orignal arg number  arg pos- short param count 1           local new arg     orignal arg number           else             break out our one argument into new ones           local new arg  -  nodash  str pos 1           fi         new args   new args    new arg          done         remove the preceding space and set the new arguments       eval set --    new args         fi     if    breakout   then       key   nodash      fi        By default we expect to shift one argument at a time     shift count 1     if       param pair      -gt  1      then         This is a param with equals notation       value    param pair 1        else         This is either a boolean param and there is no value          or the value is the next command line argument         Assume the value is a boolean true  unless the next argument is found to be a value        value true       if       -gt 1  amp  amp  -n   2      then         local nodash    2 -           if     nodash      2     then             The next argument has NO preceding dash so it is a value           value   2            shift count 2         fi       fi     fi        Check that the param being passed is one of the allowed params     if  param variant   allowed params    key    then         --key-name will now become param key name       eval param   key  -      value      else       printf  WARNING  Unknown option  ignored    s n    1   gt  amp 2     fi     shift  shift count   done     And use it like so     Assign defaults for parameters param help false param path   pwd  param file false param image true param image lossy true param image lossy quality 85    Define the params we will allow allowed params  h   help p path f file i image image-lossy image-lossy-quality     Get the params from arguments provided  get params

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In order to stay cross-platform compatible  and avoid the reliance on external executables  I ported some code from another language   I find it very easy to use  here is an example   ArgParser  addArg   h elp     false     This list  ArgParser  addArg   q uiet    false     Supress output  ArgParser  addArg   s leep    1         Seconds to sleep  ArgParser  addArg  v          1         Verbose mode   ArgParser  parse       ArgParser  isset help  amp  amp  ArgParser  showArgs  ArgParser  isset  quiet        amp  amp  echo  Quiet           echo  Noisy    local   sleep ArgParser  tryAndGetArg sleep into   sleep       amp  amp  echo  Sleep for    sleep seconds          echo  No value passed for sleep     This way is often more convienient  but is a little slower echo  Sleep set to     ArgParser  getArg sleep      The required BASH is a little longer than it could be  but I wanted to avoid reliance on BASH 4 s associative arrays   You can also download this directly from http   nt4 com bash argparser inc sh     usr bin env bash    Updates to this script may be found at   http   nt4 com bash argparser inc sh    Example of runtime usage    mnc sh --nc -q Caprica S0 mkv   avi   mp3 --more-options here --host centos8 host com    Example of use in script  see bottom    Just include this file in yours  or use   source argparser inc sh  unset EXPLODED declare -a EXPLODED function explode        local c            c  lt  2     amp  amp                 echo function   0  is missing parameters          return 1            local delimiter   1      local string   2      local limit   3-99       local tmp delim    x07      local delin   string   delimiter  tmp delim      local oldifs   IFS       IFS   tmp delim      EXPLODED   delin      IFS   oldifs        See  http   fvue nl wiki Bash  Passing variables by reference   Usage  local   1   amp  amp  upvar  1  value s   upvar         if unset -v   1   then             Unset  amp  validate varname         if          2     then             eval  1     2              Return single value         else             eval  1          2         Return array         fi     fi    function decho            function ArgParser  check         args      argparser  arglist         for    i 0  i lt   args  i          do         matched 0         explode          argparser  arglist  i            if       1   -eq 1           then             if      1         EXPLODED 0                  then                 decho  Matched  1 with   EXPLODED 0                    matched 1                  break             fi         else             if      1         EXPLODED 1                  then                 decho  Matched  1 with   EXPLODED 1                    matched 1                  break             fi         fi     done        matched    0     amp  amp  return 2       decho  Key  key has default argument of   EXPLODED 3        if      EXPLODED 3        false        then         return 0     else         return 1     fi    function ArgParser  set       key  3     value    1 -true       declare -g   argpassed   key   value     function ArgParser  parse        unset   argparser  argv       argparser  argv          echo parsing            while   -n   1        do           echo  Processing  1          if      1 0 2       --            then             key   1 2              value  2         elif      1 0 1       -            then             key   1 1                  Strip off leading -             value  2         else             decho  Not argument or option    1    gt  amp  2               argparser  argv      1                shift             continue         fi           parameter   tmp            Extract name            value   tmp                Extract value          decho  Key    key   value    value             eval  parameter  value         ArgParser  check  key         el              echo  Check returned  el for  key             el -eq  2    amp  amp  decho  No match for option   1    gt  amp 2    amp  amp    argparser  argv      1               el -eq  0    amp  amp  decho  Matched option    EXPLODED 2    with no arguments          gt  amp 2  amp  amp  ArgParser  set true    EXPLODED                 el -eq  1    amp  amp  decho  Matched option    EXPLODED 2    with an argument of   2      gt  amp 2  amp  amp  ArgParser  set   2     EXPLODED       amp  amp  shift         shift     done    function ArgParser  isset       declare -p    argpassed   1   gt   dev null 2 gt  amp 1  amp  amp  return 0     return 1    function ArgParser  getArg         This one would be a bit silly  since we can only return non-integer arguments ineffeciently     varname    argpassed   1      echo     varname           usage  tryAndGetArg  lt argname gt  into  lt varname gt    returns  0 on success  1 on failure function ArgParser  tryAndGetArg       local   varname    argpassed   1      local   value       varname       test -z     value   amp  amp  return 1     local   3   amp  amp  upvar  3     value      return 0    function ArgParser    construct       unset   argparser  arglist       declare -a   argparser  arglist          brief add command line argument    param 1 short and or long  eg   s hort    param 2 default value    param 3 description    function ArgParser  addArg         check for short arg within long arg     if      1                    then         short   BASH REMATCH 1           long   1    short    short      else         long  1     fi     if       long   -eq 1       then         short  long         long        fi     decho short    short      decho long    long        argparser  arglist     short  long  1  2  3             brief show available command line arguments    function ArgParser  showArgs         declare -p   grep argparser     printf  Usage   s  OPTION     n n      basename    BASH SOURCE 0           printf  Defaults for the options are specified in brackets  n n          args      argparser  arglist         for    i 0  i lt   args  i          do         local shortname          local fullname          local default          local description          local comma           explode          argparser  arglist  i             shortname    EXPLODED 0   -  EXPLODED 0       String Substitution Guide           fullname    EXPLODED 1   --  EXPLODED 1       http   tldp org LDP abs html parameter-substitution html         test -n   shortname                 amp  amp  test -n   fullname                 amp  amp  comma              default    EXPLODED 3            case  default in             false                   default                                                      default                                                     default    default           esac          description    EXPLODED 4             printf     2s 1s  -19s  s  s n    shortname    comma    fullname    description    default      done    function ArgParser  test         Arguments with a default of  false  do not take paramaters  note  default       values are not applied in this release       ArgParser  addArg   h elp       false        This list      ArgParser  addArg   q uiet  false        Supress output      ArgParser  addArg   s leep  1            Seconds to sleep      ArgParser  addArg  v            1            Verbose mode       ArgParser  parse           ArgParser  isset help  amp  amp  ArgParser  showArgs      ArgParser  isset  quiet             amp  amp  echo  Quiet                echo  Noisy        local   sleep     ArgParser  tryAndGetArg sleep into   sleep            amp  amp  echo  Sleep for    sleep seconds               echo  No value passed for sleep         This way is often more convienient  but is a little slower     echo  Sleep set to     ArgParser  getArg sleep         echo  Remaining command line      argparser  argv          if       basename   0         argparser inc sh    then     ArgParser  test      fi

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I don t have enough rep yet to comment or vote his solution up  but sme s answer worked extremely well for me  The only issue I ran into was that the arguments end up wrapped in single-quotes  so I have an strip them out    I also added some example usages and HELP text   I ll included my slightly extended version here      bin bash    getopt example   from  https   stackoverflow com questions 402377 using-getopts-in-bash-shell-script-to-get-long-and-short-command-line-options HELP TEXT       USAGE  n     Accepts - and -- flags  can specify options that require a value  and can be in any order  A double-hyphen  --  will stop processing options  n n      Accepts the following forms  n n      getopt-example sh -a -b -c value-for-c some-arg n     getopt-example sh -c value-for-c -a -b some-arg n     getopt-example sh -abc some-arg n     getopt-example sh --along --blong --clong value-for-c -a -b -c some-arg n     getopt-example sh some-arg --clong value-for-c n     getopt-example sh    aflag false bflag false cargument       options may be followed by one colon to indicate they have a required argument if   options   getopt -o abc h   -l along blong help clong  --       then       something went wrong  getopt will put out an error message for us     exit 1 fi  set --  options  while      -gt 0   do     case  1 in     -a --along  aflag true        -b --blong  bflag true          for options with required arguments  an additional shift is required     -c --clong  cargument   2    shift       -h --help -    echo -e  HELP TEXT  exit        --  shift  break        -   echo   0  error - unrecognized option  1  1 gt  amp 2  exit 1           break       esac     shift done    to remove the single quotes around arguments  pipe the output into      sed -e  s          g    just leading trailing  or   sed -e  s    g    all   echo aflag   aflag  echo bflag   bflag  echo cargument   cargument   while      -gt 0   do     echo arg  1     shift      if     aflag    true     then         echo a is true     fi  done

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In order to stay cross-platform compatible  and avoid the reliance on external executables  I ported some code from another language   I find it very easy to use  here is an example   ArgParser  addArg   h elp     false     This list  ArgParser  addArg   q uiet    false     Supress output  ArgParser  addArg   s leep    1         Seconds to sleep  ArgParser  addArg  v          1         Verbose mode   ArgParser  parse       ArgParser  isset help  amp  amp  ArgParser  showArgs  ArgParser  isset  quiet        amp  amp  echo  Quiet           echo  Noisy    local   sleep ArgParser  tryAndGetArg sleep into   sleep       amp  amp  echo  Sleep for    sleep seconds          echo  No value passed for sleep     This way is often more convienient  but is a little slower echo  Sleep set to     ArgParser  getArg sleep      The required BASH is a little longer than it could be  but I wanted to avoid reliance on BASH 4 s associative arrays   You can also download this directly from http   nt4 com bash argparser inc sh     usr bin env bash    Updates to this script may be found at   http   nt4 com bash argparser inc sh    Example of runtime usage    mnc sh --nc -q Caprica S0 mkv   avi   mp3 --more-options here --host centos8 host com    Example of use in script  see bottom    Just include this file in yours  or use   source argparser inc sh  unset EXPLODED declare -a EXPLODED function explode        local c            c  lt  2     amp  amp                 echo function   0  is missing parameters          return 1            local delimiter   1      local string   2      local limit   3-99       local tmp delim    x07      local delin   string   delimiter  tmp delim      local oldifs   IFS       IFS   tmp delim      EXPLODED   delin      IFS   oldifs        See  http   fvue nl wiki Bash  Passing variables by reference   Usage  local   1   amp  amp  upvar  1  value s   upvar         if unset -v   1   then             Unset  amp  validate varname         if          2     then             eval  1     2              Return single value         else             eval  1          2         Return array         fi     fi    function decho            function ArgParser  check         args      argparser  arglist         for    i 0  i lt   args  i          do         matched 0         explode          argparser  arglist  i            if       1   -eq 1           then             if      1         EXPLODED 0                  then                 decho  Matched  1 with   EXPLODED 0                    matched 1                  break             fi         else             if      1         EXPLODED 1                  then                 decho  Matched  1 with   EXPLODED 1                    matched 1                  break             fi         fi     done        matched    0     amp  amp  return 2       decho  Key  key has default argument of   EXPLODED 3        if      EXPLODED 3        false        then         return 0     else         return 1     fi    function ArgParser  set       key  3     value    1 -true       declare -g   argpassed   key   value     function ArgParser  parse        unset   argparser  argv       argparser  argv          echo parsing            while   -n   1        do           echo  Processing  1          if      1 0 2       --            then             key   1 2              value  2         elif      1 0 1       -            then             key   1 1                  Strip off leading -             value  2         else             decho  Not argument or option    1    gt  amp  2               argparser  argv      1                shift             continue         fi           parameter   tmp            Extract name            value   tmp                Extract value          decho  Key    key   value    value             eval  parameter  value         ArgParser  check  key         el              echo  Check returned  el for  key             el -eq  2    amp  amp  decho  No match for option   1    gt  amp 2    amp  amp    argparser  argv      1               el -eq  0    amp  amp  decho  Matched option    EXPLODED 2    with no arguments          gt  amp 2  amp  amp  ArgParser  set true    EXPLODED                 el -eq  1    amp  amp  decho  Matched option    EXPLODED 2    with an argument of   2      gt  amp 2  amp  amp  ArgParser  set   2     EXPLODED       amp  amp  shift         shift     done    function ArgParser  isset       declare -p    argpassed   1   gt   dev null 2 gt  amp 1  amp  amp  return 0     return 1    function ArgParser  getArg         This one would be a bit silly  since we can only return non-integer arguments ineffeciently     varname    argpassed   1      echo     varname           usage  tryAndGetArg  lt argname gt  into  lt varname gt    returns  0 on success  1 on failure function ArgParser  tryAndGetArg       local   varname    argpassed   1      local   value       varname       test -z     value   amp  amp  return 1     local   3   amp  amp  upvar  3     value      return 0    function ArgParser    construct       unset   argparser  arglist       declare -a   argparser  arglist          brief add command line argument    param 1 short and or long  eg   s hort    param 2 default value    param 3 description    function ArgParser  addArg         check for short arg within long arg     if      1                    then         short   BASH REMATCH 1           long   1    short    short      else         long  1     fi     if       long   -eq 1       then         short  long         long        fi     decho short    short      decho long    long        argparser  arglist     short  long  1  2  3             brief show available command line arguments    function ArgParser  showArgs         declare -p   grep argparser     printf  Usage   s  OPTION     n n      basename    BASH SOURCE 0           printf  Defaults for the options are specified in brackets  n n          args      argparser  arglist         for    i 0  i lt   args  i          do         local shortname          local fullname          local default          local description          local comma           explode          argparser  arglist  i             shortname    EXPLODED 0   -  EXPLODED 0       String Substitution Guide           fullname    EXPLODED 1   --  EXPLODED 1       http   tldp org LDP abs html parameter-substitution html         test -n   shortname                 amp  amp  test -n   fullname                 amp  amp  comma              default    EXPLODED 3            case  default in             false                   default                                                      default                                                     default    default           esac          description    EXPLODED 4             printf     2s 1s  -19s  s  s n    shortname    comma    fullname    description    default      done    function ArgParser  test         Arguments with a default of  false  do not take paramaters  note  default       values are not applied in this release       ArgParser  addArg   h elp       false        This list      ArgParser  addArg   q uiet  false        Supress output      ArgParser  addArg   s leep  1            Seconds to sleep      ArgParser  addArg  v            1            Verbose mode       ArgParser  parse           ArgParser  isset help  amp  amp  ArgParser  showArgs      ArgParser  isset  quiet             amp  amp  echo  Quiet                echo  Noisy        local   sleep     ArgParser  tryAndGetArg sleep into   sleep            amp  amp  echo  Sleep for    sleep seconds               echo  No value passed for sleep         This way is often more convienient  but is a little slower     echo  Sleep set to     ArgParser  getArg sleep         echo  Remaining command line      argparser  argv          if       basename   0         argparser inc sh    then     ArgParser  test      fi

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An improved solution     translate long options to short   Note  This enable long options but disable  --    in  OPTARG  or disable long options after   --  in option fields  for   i 1    i       do     case   1  in         --                    args    i-1                 EndOpt 1    amp    DIRTY  we still can handle some execptions                EndOpt 1    amp          --version    EndOpt    amp  amp  args  i    1      args  i   -V              default case   short option use the first char of the long option          --      EndOpt    amp  amp  args  i    1      args  i   -  1 2 1               pass through anything else             args  i    1         esac     shift done   reset the translated args set --    args       function usage   echo  Usage   0  options  files   gt  amp 2     exit  1      now we can process with getopt while getopts   hvVc   opt  do     case  opt in         h   usage            v   VERBOSE true            V   echo  Version   exit            c   source  OPTARG                echo  unrecognized option  - opt    usage -1                       echo  option - OPTARG requires an argument          usage -1                esac done  shift    OPTIND-1        1      --      amp  amp  shift

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Take a look at shFlags which is a portable shell library  meaning  sh  bash  dash  ksh  zsh on Linux  Solaris  etc     It makes adding new flags as simple as adding one line to your script  and it provides an auto generated usage function   Here is a simple Hello  world  using shFlag      bin sh    source shflags from current directory     shflags    define a  name  command-line string flag DEFINE string  name   world   name to say hello to   n     parse the command-line FLAGS         exit 1 eval set --    FLAGS ARGV      say hello echo  Hello    FLAGS name      For OSes that have the enhanced getopt that supports long options  e g  Linux   you can do       hello world sh --name Kate Hello  Kate    For the rest  you must use the short option       hello world sh -n Kate Hello  Kate    Adding a new flag is as simple as adding a new DEFINE  call

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The built-in getopts command is still  AFAIK  limited to single-character options only   There is  or used to be  an external program getopt that would reorganize a set of options such that it was easier to parse   You could adapt that design to handle long options too   Example usage   aflag no bflag no flist    set --   getopt abf        while      -gt 0   do     case   1  in      -a  aflag yes        -b  bflag yes        -f  flist   flist  2   shift        --  shift  break        -   echo   0  error - unrecognized option  1  1 gt  amp 2  exit 1            break       esac     shift done    Process remaining non-option arguments       You could use a similar scheme with a getoptlong command   Note that the fundamental weakness with the external getopt program is the difficulty of handling arguments with spaces in them  and in preserving those spaces accurately   This is why the built-in getopts is superior  albeit limited by the fact it only handles single-letter options

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hm   not really satisfied with the pure bash options  why not use perl to get what you want  Directly parse the    array  and auto-name your options   simple helper script      usr bin perl use Getopt  Long   my  optstring   shift   my  opts   split m      optstring    my  opt  GetOptions   opt   opts    print  set --     join      map          ARGV          my  xx   my  key  foreach  key  keys  opt         print  export  key   opt  key           then you can use in your script as a one liner  for example      bin bash  eval  getopts pl reuse s long opt s hello       echo  HELLO   hello  echo  LONG OPT   long opt  echo  REUSE   reuse   echo       tmp script sh hello --reuse me --long opt whatever you want except spaces --hello 1 2 3  HELLO  1 LONG OPT  whatever you want except spaces REUSE  me  1 2 3  Only caveat here is spaces don t work  But it avoids bash s rather complicated looping syntax  works with long args  auto-names them as variables and automatically resizes     so will work 99  of the time

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In case you don t want the getopt dependency  you can do this   while test    -gt 0 do   case  1 in      Normal option processing     -h   --help          usage and help              -v   --version          version info                       Special cases     --        break              --           error unknown  long  option  1              -           error unknown  short  option  1               FUN STUFF HERE      Split apart combined short options     -         split  1       shift       set --   echo   split    cut -c 2-   sed  s   - amp   g              continue               Done with options              break            esac      for testing purposes    echo   1     shift done   Of course  then you can t use long style options with one dash  And if you want to add shortened versions  e g  --verbos instead of --verbose   then you need to add those manually   But if you are looking to get getopts functionality along with long options  this is a simple way to do it   I also put this snippet in a gist

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In ksh93  getopts does support long names     while getopts  f file  s server    flag do     echo   flag   OPTIND  OPTARG done   Or so the tutorials I have found have said   Try it and see

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if simply this is how you want to call the script   myscript sh --input1  ABC  --input2  PQR  --input2  XYZ    then you can follow this simplest way to achieve it with the help of getopt and --longoptions   try this   hope this is useful    Read command line options ARGUMENT LIST        input1       input2       input3         read arguments opts   getopt       --longoptions    printf   s       ARGUMENT LIST              --name    basename   0          --options          --          echo  opts  eval set -- opts  while true  do     case   1  in     --input1            shift         empId  1                --input2            shift         fromDate  1                --input3            shift         toDate  1                  --          shift         break                esac     shift done

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Builtin getopts only parse short options  except in ksh93   but you can still add few lines of scripting to make getopts handles long options   Here is a part of code found in http   www uxora com unix shell-script 22-handle-long-options-with-getopts        set short options     SCRIPT OPTS   fbF B - h        set long options associated with short one     typeset -A ARRAY OPTS ARRAY OPTS        foo  f      bar  b      foobar  F      barfoo  B      help  h      man  h          parse options     while getopts   SCRIPT OPTS  OPTION   do         translate long options to short         if     x OPTION      x-      then         LONG OPTION  OPTARG         LONG OPTARG   echo  LONG OPTION   grep       cut -d    -f2          LONG OPTIND -1             x LONG OPTARG     x      amp  amp  LONG OPTIND  OPTIND    LONG OPTION   echo  OPTARG   cut -d    -f1              LONG OPTIND -ne -1     amp  amp  eval LONG OPTARG     LONG OPTIND          OPTION   ARRAY OPTS  LONG OPTION               x OPTION     x      amp  amp   OPTION     OPTARG  - LONG OPTION           if       echo    SCRIPT OPTS     grep -c    OPTION      -eq 1     then             if     x  LONG OPTARG      x              LONG OPTARG     -      then                  OPTION     OPTARG  - LONG OPTION              else                 OPTARG   LONG OPTARG                   if     LONG OPTIND -ne -1     then                         OPTIND -le  Optnum     amp  amp  OPTIND      OPTIND 1                        shift  OPTIND                     OPTIND 1                 fi             fi         fi     fi          options follow by another option instead of argument         if     x  OPTION       x       amp  amp      x  OPTION       x       amp  amp        OPTARG     -      then          OPTARG   OPTION  OPTION         fi          manage options         case   OPTION  in         f    foo 1 bar 0                               b    foo 0 bar 1                               B    barfoo   OPTARG                           F    foobar 1  amp  amp  foobar name   OPTARG             h   usagefull  amp  amp  exit 0                echo    SCRIPT NAME   - OPTARG  option requires an argument   gt  amp 2  amp  amp  usage  gt  amp 2  amp  amp  exit 99                echo    SCRIPT NAME   - OPTARG  unknown option   gt  amp 2  amp  amp  usage  gt  amp 2  amp  amp  exit 99        esac done shift      OPTIND  - 1     Here is a test     Short options test     foobar any getopts sh -bF  Hello world  -B 6 file1 file2 foo 0 bar 1 barfoo 6 foobar 1 foobar name Hello world files file1 file2    Long and short options test     foobar any getopts sh --bar -F Hello --barfoo 6 file1 file2 foo 0 bar 1 barfoo 6 foobar 1 foobar name Hello files file1 file2   Otherwise in recent Korn Shell ksh93  getopts can naturally parse long options and even display a man page alike   See http   www uxora com unix shell-script 20-getopts-with-man-page-and-long-options

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An improved solution     translate long options to short   Note  This enable long options but disable  --    in  OPTARG  or disable long options after   --  in option fields  for   i 1    i       do     case   1  in         --                    args    i-1                 EndOpt 1    amp    DIRTY  we still can handle some execptions                EndOpt 1    amp          --version    EndOpt    amp  amp  args  i    1      args  i   -V              default case   short option use the first char of the long option          --      EndOpt    amp  amp  args  i    1      args  i   -  1 2 1               pass through anything else             args  i    1         esac     shift done   reset the translated args set --    args       function usage   echo  Usage   0  options  files   gt  amp 2     exit  1      now we can process with getopt while getopts   hvVc   opt  do     case  opt in         h   usage            v   VERBOSE true            V   echo  Version   exit            c   source  OPTARG                echo  unrecognized option  - opt    usage -1                       echo  option - OPTARG requires an argument          usage -1                esac done  shift    OPTIND-1        1      --      amp  amp  shift

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bin bash while getopts  abc d   flag do   case  flag in     a  echo   getopts  OPTIND    gt  - flag        b  echo   getopts  OPTIND    gt  - flag        c  echo   getopts  OPTIND    gt  - flag  OPTARG        d  echo   getopts  OPTIND    gt  - flag  OPTARG      esac done  shift    OPTIND-1   echo   otheropts    gt       exit         bin bash until   -z   1     do   case  1 in      --dlong         shift       if      1 1 0       -          then         echo     gt  dlong  1          shift       fi          echo     gt  other  1   shift     esac done exit

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Long options can be parsed by the standard getopts builtin as    arguments    to the -    option    This is portable and native POSIX shell     no external programs or bashisms are needed  This guide implements long options as arguments to the - option  so --alpha is seen by getopts as - with argument alpha and --bravo foo is seen as - with argument bravo foo   The true argument can be harvested with a simple replacement    OPTARG      In this example  -b and -c  and their long forms  --bravo and --charlie  have mandatory arguments   Arguments to long options come after equals signs  e g  --bravo foo  space delimiters for long options would be hard to implement  see below   Because this uses the getopts builtin  this solution supports usage like cmd --bravo foo -ac FILE  which has combined options -a and -c and interleaves long options with standard options  while most other answers here either struggle or fail to do that  die     echo  quot    quot   gt  amp 2  exit 2       complain to STDERR and exit with error needs arg     if   -z  quot  OPTARG quot     then die  quot No arg for -- OPT option quot   fi     while getopts ab c -  OPT  do     support long options  https   stackoverflow com a 28466267 519360   if    quot  OPT quot     quot - quot     then     long option  reformulate OPT and OPTARG     OPT  quot   OPTARG      quot          extract long option name     OPTARG  quot   OPTARG  OPT  quot      extract long option argument  may be empty      OPTARG  quot   OPTARG    quot         if long option argument  remove assigning       fi   case  quot  OPT quot  in     a   alpha      alpha true        b   bravo      needs arg  bravo  quot  OPTARG quot         c   charlie    needs arg  charlie  quot  OPTARG quot                        die  quot Illegal option -- OPT quot        bad long option                    exit 2       bad short option  error reported via getopts    esac done shift    OPTIND-1     remove parsed options and args from    list  When the option is a dash  -   it is a long option  getopts will have parsed the actual long option into  OPTARG  e g  --bravo foo originally sets OPT  -  and OPTARG  bravo foo   The if stanza sets  OPT to the contents of  OPTARG before the first equals sign  bravo in our example  and then removes that from the beginning of  OPTARG  yielding  foo in this step  or an empty string if there is no     Finally  we strip the argument s leading    At this point   OPT is either a short option  one character  or a long option  2  characters   The case then matches either short or long options  For short options  getopts automatically complains about options and missing arguments  so we have to replicate those manually using the needs arg function  which fatally exits when  OPTARG is empty  The     condition will match any remaining long option    matches a single character and   matches zero or more  so     matches 2  characters   allowing us to issue the  quot Illegal option quot  error before exiting  Minor bug  if somebody gives an invalid single-character long option  and it s not also a short option   this will exit with an error but without a message  This is because this implementation assumes it was a short option  You could track that with an extra variable in the long option stanza preceding the case and then test for it in the final case condition  but I consider that too much of a corner case to bother   A note about all-uppercase variable names  Generally  the advice is to reserve all-uppercase variables for system use  I m keeping  OPT as all-uppercase to keep it in line with  OPTARG  but this does break that convention  I think it fits because this is something the system should have done  and it should be safe because there are no standards  afaik  that use such a variable    To complain about unexpected arguments to long options  mimic what we did for mandatory arguments  use a helper function  Just flip the test around to complain about an argument when one isn t expected  no arg     if   -n  quot  OPTARG quot     then die  quot No arg allowed for -- OPT option quot   fi      An older version of this answer had an attempt at accepting long options with space-delimited arguments  but it was not reliable  getopts could prematurely terminate on the assumption that the argument was beyond its scope and manually incrementing  OPTIND doesn t work in all shells  This would be accomplished using one of these techniques depending on your shell   POSIX eval  eval  quot bravo   quot    OPTIND  quot  quot  Bash indirect expansion  bravo  quot    OPTIND  quot  Zsh parameter expansion P flag  bravo  quot    P OPTIND  quot   and then concluded with something like      -gt  OPTIND    amp  amp  OPTIND    OPTIND 1

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Inventing yet another version of the wheel     This function is a  hopefully  POSIX-compatible plain bourne shell replacement for GNU getopt  It supports short long options which can accept mandatory optional no arguments  and the way in which options are specified is almost identical to GNU getopt  so conversion is trivial   Of course this is still a sizeable chunk of code to drop into a script  but it s about half the lines of the well-known getopt long shell function  and might be preferable in cases where you just want to replace existing GNU getopt uses   This is pretty new code  so YMMV  and definitely please let me know if this isn t actually POSIX-compatible for any reason -- portability was the intention from the outset  but I don t have a useful POSIX test environment    Code and example usage follows      bin sh   posix getopt shell function   Author  Phil S    Version  1 0   Created  2016-07-05   URL  http   stackoverflow com a 37087374 324105    POSIX-compatible argument quoting and parameter save restore   http   www etalabs net sh tricks html   Usage    parameters   save         save the original parameters    eval  set --   parameters     restore the saved parameters  save          local param     for param  do         printf  s  n   param                  sed  s           g 1s        s                 done     printf  s  n          Exit with status  1 after displaying error message  2  exiterr          printf  s  n   2   gt  amp 2     exit  1      POSIX-compatible command line option parsing    This function supports long options and optional arguments  and is   a  largely-compatible  drop-in replacement for GNU getopt      Instead of    opts   getopt -o   shortopts  -l   longopts  --         eval set --   opts      We instead use    opts   posix getopt   shortopts    longopts          eval  set --   opts   posix getopt        args    shortopts    longopts           local shortopts longopts             arg argtype getopt nonopt opt optchar optword suffix      shortopts   1      longopts   2      shift 2      getopt      nonopt      while      -gt 0    do         opt          arg          argtype          case   1  in                --  means don t parse the remaining options               --                     getopt    getopt   save                        shift                    break                               process short option               -  -                 -x foo                  suffix   1 -       foo                 opt   1  suffix    -x                 optchar   opt -    x                 case    shortopts   in                          optchar           optional argument                         argtype optional                         arg    suffix                           shift                                                  optchar          required argument                         argtype required                         if   -n    suffix      then                             arg    suffix                               shift                         else                             case   2  in                                   -    exiterr 1   1 requires an argument                                           arg   2   shift 2                                          exiterr 1   1 requires an argument                                esac                         fi                                                  optchar         no argument                         argtype none                         arg                          shift                           Handle multiple no-argument parameters combined as                           -xyz instead of -x -y -z  If we have just shifted                           parameter -xyz  we now replace it with -yz  which                           will be processed in the next iteration                           if   -n    suffix      then                             eval  set --   save  -  suffix     save                                fi                                                   exiterr 1  Unknown option  1                    esac                               process long option               --                    --xarg  foo                  suffix   1          foo  unless there was no                    if      suffix       1     then                     suffix                  fi                 opt   1   suffix    --xarg                 optword   opt --    xarg                 case     longopts    in                           optword            optional argument                         argtype optional                         arg    suffix                           shift                                                   optword           required argument                         argtype required                         if   -n    suffix      then                             arg    suffix                               shift                         else                             case   2  in                                   -    exiterr 1                                           --  optword  requires an argument                                           arg   2   shift 2                                          exiterr 1                                           --  optword  requires an argument                                esac                         fi                                                   optword          no argument                         if   -n    suffix      then                             exiterr 1  --  optword  does not take an argument                          fi                         argtype none                         arg                          shift                                                   exiterr 1  Unknown option  1                    esac                               any other parameters starting with -               -    exiterr 1  Unknown option  1                  remember non-option parameters                   nonopt    nonopt   save   1     shift           esac          if   -n    opt      then             getopt    getopt   save   opt                case    argtype   in                   optional required                         getopt    getopt   save   arg                                    esac         fi     done        Generate function output  suitable for        eval  set --   posix getopt           printf  s    getopt       if   -n    nonopt      then         printf  s    save  --    nonopt       fi     Example usage     Process command line options shortopts  hvd c  s  L D  longopts  help version directory  client   server   load  delete   opts   getopt -o   shortopts  -l   longopts  -n    basename  0   --       opts   posix getopt   shortopts    longopts        if      -eq 0    then      eval set --   opts      eval  set --   opts       while      -gt 0    do         case   1  in               --                  shift  break                 -h --help           help 1  shift  break                 -v --version        version help 1  shift  break                 -d --directory      dir  2  shift 2                 -c --client         useclient 1  client  2  shift 2                 -s --server         startserver 1  server name  2  shift 2                 -L --load           load  2  shift 2                 -D --delete         delete 1  shift           esac     done else     shorthelp 1   getopt returned  and reported  an error  fi

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Builtin getopts only parse short options  except in ksh93   but you can still add few lines of scripting to make getopts handles long options   Here is a part of code found in http   www uxora com unix shell-script 22-handle-long-options-with-getopts        set short options     SCRIPT OPTS   fbF B - h        set long options associated with short one     typeset -A ARRAY OPTS ARRAY OPTS        foo  f      bar  b      foobar  F      barfoo  B      help  h      man  h          parse options     while getopts   SCRIPT OPTS  OPTION   do         translate long options to short         if     x OPTION      x-      then         LONG OPTION  OPTARG         LONG OPTARG   echo  LONG OPTION   grep       cut -d    -f2          LONG OPTIND -1             x LONG OPTARG     x      amp  amp  LONG OPTIND  OPTIND    LONG OPTION   echo  OPTARG   cut -d    -f1              LONG OPTIND -ne -1     amp  amp  eval LONG OPTARG     LONG OPTIND          OPTION   ARRAY OPTS  LONG OPTION               x OPTION     x      amp  amp   OPTION     OPTARG  - LONG OPTION           if       echo    SCRIPT OPTS     grep -c    OPTION      -eq 1     then             if     x  LONG OPTARG      x              LONG OPTARG     -      then                  OPTION     OPTARG  - LONG OPTION              else                 OPTARG   LONG OPTARG                   if     LONG OPTIND -ne -1     then                         OPTIND -le  Optnum     amp  amp  OPTIND      OPTIND 1                        shift  OPTIND                     OPTIND 1                 fi             fi         fi     fi          options follow by another option instead of argument         if     x  OPTION       x       amp  amp      x  OPTION       x       amp  amp        OPTARG     -      then          OPTARG   OPTION  OPTION         fi          manage options         case   OPTION  in         f    foo 1 bar 0                               b    foo 0 bar 1                               B    barfoo   OPTARG                           F    foobar 1  amp  amp  foobar name   OPTARG             h   usagefull  amp  amp  exit 0                echo    SCRIPT NAME   - OPTARG  option requires an argument   gt  amp 2  amp  amp  usage  gt  amp 2  amp  amp  exit 99                echo    SCRIPT NAME   - OPTARG  unknown option   gt  amp 2  amp  amp  usage  gt  amp 2  amp  amp  exit 99        esac done shift      OPTIND  - 1     Here is a test     Short options test     foobar any getopts sh -bF  Hello world  -B 6 file1 file2 foo 0 bar 1 barfoo 6 foobar 1 foobar name Hello world files file1 file2    Long and short options test     foobar any getopts sh --bar -F Hello --barfoo 6 file1 file2 foo 0 bar 1 barfoo 6 foobar 1 foobar name Hello files file1 file2   Otherwise in recent Korn Shell ksh93  getopts can naturally parse long options and even display a man page alike   See http   www uxora com unix shell-script 20-getopts-with-man-page-and-long-options

User · Answer

If all your long options have unique  and matching  first characters as the short options  so for example    slamm --chaos 23 --plenty test -quiet   Is the same as    slamm -c 23 -p test -q   You can use this before getopts to rewrite  args     change long options to short options  for arg  do            arg 0 1       -      amp  amp  delim       delim          if      arg 0 2       --             then args    args  -  arg 2 1           else args    args    delim   arg   delim       fi done    reset the incoming args eval set --  args    proceed as usual while getopts   b la h  OPTION  do             Thanks for mtvee for the inspiration  -

User · Answer

Maybe it s simpler to use ksh  just for the getopts part  if need long command line options  as it can be easier done there     Working Getopts Long   gt  KSH      bin ksh   Getopts Long USAGE  s showconfig   USAGE   c  createdb   USAGE   l  createlistener   USAGE   g  generatescripts   USAGE   r  removedb   USAGE   x  removelistener   USAGE   t  createtemplate   USAGE   h help    while getopts   USAGE  optchar   do     case  optchar in     s   echo  Displaying Configuration             c   echo  Creating Database  OPTARG         l   echo  Creating Listener LISTENER  OPTARG         g   echo  Generating Scripts for Database  OPTARG         r   echo  Removing Database  OPTARG         x   echo  Removing Listener LISTENER  OPTARG         t   echo  Creating Database Template         h   echo  Help         esac done

User · Answer

bin bash while getopts  abc d   flag do   case  flag in     a  echo   getopts  OPTIND    gt  - flag        b  echo   getopts  OPTIND    gt  - flag        c  echo   getopts  OPTIND    gt  - flag  OPTARG        d  echo   getopts  OPTIND    gt  - flag  OPTARG      esac done  shift    OPTIND-1   echo   otheropts    gt       exit         bin bash until   -z   1     do   case  1 in      --dlong         shift       if      1 1 0       -          then         echo     gt  dlong  1          shift       fi          echo     gt  other  1   shift     esac done exit

User · Answer

if simply this is how you want to call the script   myscript sh --input1  ABC  --input2  PQR  --input2  XYZ    then you can follow this simplest way to achieve it with the help of getopt and --longoptions   try this   hope this is useful    Read command line options ARGUMENT LIST        input1       input2       input3         read arguments opts   getopt       --longoptions    printf   s       ARGUMENT LIST              --name    basename   0          --options          --          echo  opts  eval set -- opts  while true  do     case   1  in     --input1            shift         empId  1                --input2            shift         fromDate  1                --input3            shift         toDate  1                  --          shift         break                esac     shift done

User · Answer

If all your long options have unique  and matching  first characters as the short options  so for example    slamm --chaos 23 --plenty test -quiet   Is the same as    slamm -c 23 -p test -q   You can use this before getopts to rewrite  args     change long options to short options  for arg  do            arg 0 1       -      amp  amp  delim       delim          if      arg 0 2       --             then args    args  -  arg 2 1           else args    args    delim   arg   delim       fi done    reset the incoming args eval set --  args    proceed as usual while getopts   b la h  OPTION  do             Thanks for mtvee for the inspiration  -

User · Answer

The accepted answer does a very nice job of pointing out all the shortcomings of bash built-in getopts  The answer ends with      So while it is possible to write more code to work around the lack of support for long options  this is a lot more work and partially defeats the purpose of using a getopt parser to simplify your code    And even though I agree in principle with that statement  I feel that the number of times we all implemented this feature in various scripts justifies putting a bit of effort into creating a  standardised   well tested solution   As such  I ve  upgraded  bash built in getopts by implementing getopts long in pure bash  with no external dependencies  The usage of the function is 100  compatible  with the built-in getopts   By including getopts long  which is hosted on GitHub  in a script  the answer to the original question can be implemented as simply as   source    PATH TO  getopts long bash   while getopts long   c  copyfile   OPTKEY  do     case   OPTKEY  in          c   copyfile               echo  file supplied --   OPTARG                                           echo  INVALID OPTION --   OPTARG    gt  amp 2             exit 1                                         echo  MISSING ARGUMENT for option --   OPTARG    gt  amp 2             exit 1                                       echo  Misconfigured OPTSPEC or uncaught option --   OPTKEY    gt  amp 2             exit 1                    esac done  shift     OPTIND - 1          1       --      amp  amp  shift

User · Answer

getopts  could be used  for parsing long options as long as you don t expect them to have arguments     Here s how to     cat  gt  longopt while getopts  e -   OPT  do   case  OPT in     e  echo echo   OPTARG       -   long option        case  OPTARG in          long-option  echo long option               echo long option   OPTARG          esac     esac done    bash longopt -e asd --long-option --long1 --long2 -e test echo  asd long option long option  long1 long option  long2 echo  test   If you try to use OPTIND for getting a parameter for the long option  getopts will treat it as the first no optional positional parameter and will stop parsing any other parameters   In such a case you ll be better off handling it manually with a simple case statement   This will  always  work     cat  gt longopt2 while         do     OPT  1     shift     case  OPT in         --   case   OPT 2  in             long1  echo long1 option               complex  echo comples with argument  1  shift           esac            -   case   OPT 1  in             a  echo short option a               b  echo short option b with parameter  1  shift           esac       esac done     bash longopt2 --complex abc -a --long -b test comples with argument abc short option a short option b with parameter test   Albeit is not as flexible as getopts and you have to do much of the error checking code yourself within the case instances     But it is an option

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I don t have enough rep yet to comment or vote his solution up  but sme s answer worked extremely well for me  The only issue I ran into was that the arguments end up wrapped in single-quotes  so I have an strip them out    I also added some example usages and HELP text   I ll included my slightly extended version here      bin bash    getopt example   from  https   stackoverflow com questions 402377 using-getopts-in-bash-shell-script-to-get-long-and-short-command-line-options HELP TEXT       USAGE  n     Accepts - and -- flags  can specify options that require a value  and can be in any order  A double-hyphen  --  will stop processing options  n n      Accepts the following forms  n n      getopt-example sh -a -b -c value-for-c some-arg n     getopt-example sh -c value-for-c -a -b some-arg n     getopt-example sh -abc some-arg n     getopt-example sh --along --blong --clong value-for-c -a -b -c some-arg n     getopt-example sh some-arg --clong value-for-c n     getopt-example sh    aflag false bflag false cargument       options may be followed by one colon to indicate they have a required argument if   options   getopt -o abc h   -l along blong help clong  --       then       something went wrong  getopt will put out an error message for us     exit 1 fi  set --  options  while      -gt 0   do     case  1 in     -a --along  aflag true        -b --blong  bflag true          for options with required arguments  an additional shift is required     -c --clong  cargument   2    shift       -h --help -    echo -e  HELP TEXT  exit        --  shift  break        -   echo   0  error - unrecognized option  1  1 gt  amp 2  exit 1           break       esac     shift done    to remove the single quotes around arguments  pipe the output into      sed -e  s          g    just leading trailing  or   sed -e  s    g    all   echo aflag   aflag  echo bflag   bflag  echo cargument   cargument   while      -gt 0   do     echo arg  1     shift      if     aflag    true     then         echo a is true     fi  done

User · Answer

Another way       translate long options to short for arg do     delim        case   arg  in        --help  args    args -h            --verbose  args    args -v            --config  args    args -c              pass through anything else                 arg 0 1       -        delim                 args    args   delim   arg   delim          esac done   reset the translated args eval set --  args   now we can process with getopt while getopts   hvc   opt  do     case  opt in         h   usage            v   VERBOSE true            c   source  OPTARG                usage                       echo  option - OPTARG requires an argument          usage                esac done

User · Answer

Using getopts with short long options and arguments    Works with all combinations  e g    foobar -f --bar foobar --foo -b foobar -bf --bar --foobar foobar -fbFBAshorty --bar -FB --arguments longhorn foobar -fA  text shorty  -B --arguments  text longhorn  bash foobar -F --barfoo sh foobar -B --foobar -     bash   foobar -F --bar     Some declarations for this example  Options    Optnum    sfoo  no   sbar  no   sfoobar  no   sbarfoo  no   sarguments  no   sARG empty lfoo  no   lbar  no   lfoobar  no   lbarfoo  no   larguments  no   lARG empty   How the Usage function would look  function  usage               U S A G E   Help and ERROR          cat  lt  lt EOF    foobar  Options                Usage  foobar  lt  options  gt            Options                    -b   --bar            Set bar to yes      foo                    -f   --foo            Set foo to yes      bart                    -h   --help           Show this message                   -A   --arguments      Set arguments to yes   arguments  AND get ARGUMENT   ARG                    -B   --barfoo         Set barfoo to yes   barfoo                    -F   --foobar         Set foobar to yes   foobar  EOF           0    amp  amp   usage     gt  gt  gt  gt  gt  gt  gt  gt  no options given     getops with long short flags as well as long arguments  while getopts   bfh-A BF  OPTION   do   case   OPTION  in     b    sbar yes                              f    sfoo yes                              h     usage                                   A    sarguments yes sARG   OPTARG          B    sbarfoo yes                           F    sfoobar yes                           -       OPTIND -ge 1    amp  amp  optind   expr  OPTIND - 1      optind  OPTIND          eval OPTION     optind           OPTARG   echo  OPTION   cut -d    -f2           OPTION   echo  OPTION   cut -d    -f1           case  OPTION in              --foo         lfoo yes                                       --bar         lbar yes                                       --foobar      lfoobar yes                                    --barfoo      lbarfoo yes                                    --help         usage                                         --arguments   larguments yes lARG   OPTARG                          usage   Long   gt  gt  gt  gt  gt  gt  gt  gt  invalid options  long                esac        OPTIND 1        shift                    usage  Short   gt  gt  gt  gt  gt  gt  gt  gt  invalid options  short          esac done   Output                                                                     echo  ----------------------------------------------------------  echo  RESULT short-foo         sfoo                                    long-foo         lfoo  echo  RESULT short-bar         sbar                                    long-bar         lbar  echo  RESULT short-foobar      sfoobar                                 long-foobar      lfoobar  echo  RESULT short-barfoo      sbarfoo                                 long-barfoo      lbarfoo  echo  RESULT short-arguments   sarguments  with Argument      sARG     long-arguments   larguments and  lARG      Combining the above into a cohesive script     bin bash   foobar  getopts with short and long options AND arguments  function  cleanup        unset -f  usage  cleanup   return 0       Clear out nested functions on exit trap  cleanup INT EXIT RETURN         some declarations for this example        Options    Optnum    sfoo  no   sbar  no   sfoobar  no   sbarfoo  no   sarguments  no   sARG empty lfoo  no   lbar  no   lfoobar  no   lbarfoo  no   larguments  no   lARG empty  function  usage               U S A G E   Help and ERROR          cat  lt  lt EOF    foobar  Options                 Usage  foobar  lt  options  gt            Options                    -b   --bar            Set bar to yes      foo                      -f   --foo            Set foo to yes      bart                        -h   --help           Show this message                   -A   --arguments      Set arguments to yes   arguments  AND get ARGUMENT   ARG                    -B   --barfoo         Set barfoo to yes   barfoo                    -F   --foobar         Set foobar to yes   foobar  EOF           0    amp  amp   usage     gt  gt  gt  gt  gt  gt  gt  gt  no options given                                                                                     getopts  with  short options  AND  long options                             AND  short long arguments                       while getopts   bfh-A BF  OPTION   do   case   OPTION  in     b    sbar yes                              f    sfoo yes                              h     usage                                   A    sarguments yes sARG   OPTARG          B    sbarfoo yes                           F    sfoobar yes                           -       OPTIND -ge 1    amp  amp  optind   expr  OPTIND - 1      optind  OPTIND          eval OPTION     optind           OPTARG   echo  OPTION   cut -d    -f2           OPTION   echo  OPTION   cut -d    -f1           case  OPTION in              --foo         lfoo yes                                       --bar         lbar yes                                       --foobar      lfoobar yes                                    --barfoo      lbarfoo yes                                    --help         usage                                           --arguments   larguments yes lARG   OPTARG                          usage   Long   gt  gt  gt  gt  gt  gt  gt  gt  invalid options  long                esac        OPTIND 1        shift                    usage  Short   gt  gt  gt  gt  gt  gt  gt  gt  invalid options  short          esac done

User · Answer

There are three implementations that may be considered    Bash builtin getopts  This does not support long option names with the double-dash prefix   It only supports single-character options  BSD UNIX implementation of standalone getopt command  which is what MacOS uses   This does not support long options either  GNU implementation of standalone getopt   GNU getopt 3   used by the command-line getopt 1  on Linux  supports parsing long options        Some other answers show a solution for using the bash builtin getopts to mimic long options  That solution actually makes a short option whose character is  -   So you get  --  as the flag  Then anything following that becomes OPTARG  and you test the OPTARG with a nested case   This is clever  but it comes with caveats     getopts can t enforce the opt spec  It can t return errors if the user supplies an invalid option  You have to do your own error-checking as you parse OPTARG  OPTARG is used for the long option name  which complicates usage when your long option itself has an argument  You end up having to code that yourself as an additional case    So while it is possible to write more code to work around the lack of support for long options  this is a lot more work and partially defeats the purpose of using a getopt parser to simplify your code

User · Answer

Using getopts with short long options and arguments    Works with all combinations  e g    foobar -f --bar foobar --foo -b foobar -bf --bar --foobar foobar -fbFBAshorty --bar -FB --arguments longhorn foobar -fA  text shorty  -B --arguments  text longhorn  bash foobar -F --barfoo sh foobar -B --foobar -     bash   foobar -F --bar     Some declarations for this example  Options    Optnum    sfoo  no   sbar  no   sfoobar  no   sbarfoo  no   sarguments  no   sARG empty lfoo  no   lbar  no   lfoobar  no   lbarfoo  no   larguments  no   lARG empty   How the Usage function would look  function  usage               U S A G E   Help and ERROR          cat  lt  lt EOF    foobar  Options                Usage  foobar  lt  options  gt            Options                    -b   --bar            Set bar to yes      foo                    -f   --foo            Set foo to yes      bart                    -h   --help           Show this message                   -A   --arguments      Set arguments to yes   arguments  AND get ARGUMENT   ARG                    -B   --barfoo         Set barfoo to yes   barfoo                    -F   --foobar         Set foobar to yes   foobar  EOF           0    amp  amp   usage     gt  gt  gt  gt  gt  gt  gt  gt  no options given     getops with long short flags as well as long arguments  while getopts   bfh-A BF  OPTION   do   case   OPTION  in     b    sbar yes                              f    sfoo yes                              h     usage                                   A    sarguments yes sARG   OPTARG          B    sbarfoo yes                           F    sfoobar yes                           -       OPTIND -ge 1    amp  amp  optind   expr  OPTIND - 1      optind  OPTIND          eval OPTION     optind           OPTARG   echo  OPTION   cut -d    -f2           OPTION   echo  OPTION   cut -d    -f1           case  OPTION in              --foo         lfoo yes                                       --bar         lbar yes                                       --foobar      lfoobar yes                                    --barfoo      lbarfoo yes                                    --help         usage                                         --arguments   larguments yes lARG   OPTARG                          usage   Long   gt  gt  gt  gt  gt  gt  gt  gt  invalid options  long                esac        OPTIND 1        shift                    usage  Short   gt  gt  gt  gt  gt  gt  gt  gt  invalid options  short          esac done   Output                                                                     echo  ----------------------------------------------------------  echo  RESULT short-foo         sfoo                                    long-foo         lfoo  echo  RESULT short-bar         sbar                                    long-bar         lbar  echo  RESULT short-foobar      sfoobar                                 long-foobar      lfoobar  echo  RESULT short-barfoo      sbarfoo                                 long-barfoo      lbarfoo  echo  RESULT short-arguments   sarguments  with Argument      sARG     long-arguments   larguments and  lARG      Combining the above into a cohesive script     bin bash   foobar  getopts with short and long options AND arguments  function  cleanup        unset -f  usage  cleanup   return 0       Clear out nested functions on exit trap  cleanup INT EXIT RETURN         some declarations for this example        Options    Optnum    sfoo  no   sbar  no   sfoobar  no   sbarfoo  no   sarguments  no   sARG empty lfoo  no   lbar  no   lfoobar  no   lbarfoo  no   larguments  no   lARG empty  function  usage               U S A G E   Help and ERROR          cat  lt  lt EOF    foobar  Options                 Usage  foobar  lt  options  gt            Options                    -b   --bar            Set bar to yes      foo                      -f   --foo            Set foo to yes      bart                        -h   --help           Show this message                   -A   --arguments      Set arguments to yes   arguments  AND get ARGUMENT   ARG                    -B   --barfoo         Set barfoo to yes   barfoo                    -F   --foobar         Set foobar to yes   foobar  EOF           0    amp  amp   usage     gt  gt  gt  gt  gt  gt  gt  gt  no options given                                                                                     getopts  with  short options  AND  long options                             AND  short long arguments                       while getopts   bfh-A BF  OPTION   do   case   OPTION  in     b    sbar yes                              f    sfoo yes                              h     usage                                   A    sarguments yes sARG   OPTARG          B    sbarfoo yes                           F    sfoobar yes                           -       OPTIND -ge 1    amp  amp  optind   expr  OPTIND - 1      optind  OPTIND          eval OPTION     optind           OPTARG   echo  OPTION   cut -d    -f2           OPTION   echo  OPTION   cut -d    -f1           case  OPTION in              --foo         lfoo yes                                       --bar         lbar yes                                       --foobar      lfoobar yes                                    --barfoo      lbarfoo yes                                    --help         usage                                           --arguments   larguments yes lARG   OPTARG                          usage   Long   gt  gt  gt  gt  gt  gt  gt  gt  invalid options  long                esac        OPTIND 1        shift                    usage  Short   gt  gt  gt  gt  gt  gt  gt  gt  invalid options  short          esac done

User · Answer

getopts  could be used  for parsing long options as long as you don t expect them to have arguments     Here s how to     cat  gt  longopt while getopts  e -   OPT  do   case  OPT in     e  echo echo   OPTARG       -   long option        case  OPTARG in          long-option  echo long option               echo long option   OPTARG          esac     esac done    bash longopt -e asd --long-option --long1 --long2 -e test echo  asd long option long option  long1 long option  long2 echo  test   If you try to use OPTIND for getting a parameter for the long option  getopts will treat it as the first no optional positional parameter and will stop parsing any other parameters   In such a case you ll be better off handling it manually with a simple case statement   This will  always  work     cat  gt longopt2 while         do     OPT  1     shift     case  OPT in         --   case   OPT 2  in             long1  echo long1 option               complex  echo comples with argument  1  shift           esac            -   case   OPT 1  in             a  echo short option a               b  echo short option b with parameter  1  shift           esac       esac done     bash longopt2 --complex abc -a --long -b test comples with argument abc short option a short option b with parameter test   Albeit is not as flexible as getopts and you have to do much of the error checking code yourself within the case instances     But it is an option

User · Answer

In case you don t want the getopt dependency  you can do this   while test    -gt 0 do   case  1 in      Normal option processing     -h   --help          usage and help              -v   --version          version info                       Special cases     --        break              --           error unknown  long  option  1              -           error unknown  short  option  1               FUN STUFF HERE      Split apart combined short options     -         split  1       shift       set --   echo   split    cut -c 2-   sed  s   - amp   g              continue               Done with options              break            esac      for testing purposes    echo   1     shift done   Of course  then you can t use long style options with one dash  And if you want to add shortened versions  e g  --verbos instead of --verbose   then you need to add those manually   But if you are looking to get getopts functionality along with long options  this is a simple way to do it   I also put this snippet in a gist

User · Answer

Long options can be parsed by the standard getopts builtin as    arguments    to the -    option    This is portable and native POSIX shell     no external programs or bashisms are needed  This guide implements long options as arguments to the - option  so --alpha is seen by getopts as - with argument alpha and --bravo foo is seen as - with argument bravo foo   The true argument can be harvested with a simple replacement    OPTARG      In this example  -b and -c  and their long forms  --bravo and --charlie  have mandatory arguments   Arguments to long options come after equals signs  e g  --bravo foo  space delimiters for long options would be hard to implement  see below   Because this uses the getopts builtin  this solution supports usage like cmd --bravo foo -ac FILE  which has combined options -a and -c and interleaves long options with standard options  while most other answers here either struggle or fail to do that  die     echo  quot    quot   gt  amp 2  exit 2       complain to STDERR and exit with error needs arg     if   -z  quot  OPTARG quot     then die  quot No arg for -- OPT option quot   fi     while getopts ab c -  OPT  do     support long options  https   stackoverflow com a 28466267 519360   if    quot  OPT quot     quot - quot     then     long option  reformulate OPT and OPTARG     OPT  quot   OPTARG      quot          extract long option name     OPTARG  quot   OPTARG  OPT  quot      extract long option argument  may be empty      OPTARG  quot   OPTARG    quot         if long option argument  remove assigning       fi   case  quot  OPT quot  in     a   alpha      alpha true        b   bravo      needs arg  bravo  quot  OPTARG quot         c   charlie    needs arg  charlie  quot  OPTARG quot                        die  quot Illegal option -- OPT quot        bad long option                    exit 2       bad short option  error reported via getopts    esac done shift    OPTIND-1     remove parsed options and args from    list  When the option is a dash  -   it is a long option  getopts will have parsed the actual long option into  OPTARG  e g  --bravo foo originally sets OPT  -  and OPTARG  bravo foo   The if stanza sets  OPT to the contents of  OPTARG before the first equals sign  bravo in our example  and then removes that from the beginning of  OPTARG  yielding  foo in this step  or an empty string if there is no     Finally  we strip the argument s leading    At this point   OPT is either a short option  one character  or a long option  2  characters   The case then matches either short or long options  For short options  getopts automatically complains about options and missing arguments  so we have to replicate those manually using the needs arg function  which fatally exits when  OPTARG is empty  The     condition will match any remaining long option    matches a single character and   matches zero or more  so     matches 2  characters   allowing us to issue the  quot Illegal option quot  error before exiting  Minor bug  if somebody gives an invalid single-character long option  and it s not also a short option   this will exit with an error but without a message  This is because this implementation assumes it was a short option  You could track that with an extra variable in the long option stanza preceding the case and then test for it in the final case condition  but I consider that too much of a corner case to bother   A note about all-uppercase variable names  Generally  the advice is to reserve all-uppercase variables for system use  I m keeping  OPT as all-uppercase to keep it in line with  OPTARG  but this does break that convention  I think it fits because this is something the system should have done  and it should be safe because there are no standards  afaik  that use such a variable    To complain about unexpected arguments to long options  mimic what we did for mandatory arguments  use a helper function  Just flip the test around to complain about an argument when one isn t expected  no arg     if   -n  quot  OPTARG quot     then die  quot No arg allowed for -- OPT option quot   fi      An older version of this answer had an attempt at accepting long options with space-delimited arguments  but it was not reliable  getopts could prematurely terminate on the assumption that the argument was beyond its scope and manually incrementing  OPTIND doesn t work in all shells  This would be accomplished using one of these techniques depending on your shell   POSIX eval  eval  quot bravo   quot    OPTIND  quot  quot  Bash indirect expansion  bravo  quot    OPTIND  quot  Zsh parameter expansion P flag  bravo  quot    P OPTIND  quot   and then concluded with something like      -gt  OPTIND    amp  amp  OPTIND    OPTIND 1

User · Answer

In ksh93  getopts does support long names     while getopts  f file  s server    flag do     echo   flag   OPTIND  OPTARG done   Or so the tutorials I have found have said   Try it and see

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The Bash builtin getopts function can be used to parse long options by putting a dash character followed by a colon into the optspec      usr bin env bash  optspec   hv-   while getopts   optspec  optchar  do     case    optchar   in         -              case    OPTARG   in                 loglevel                      val     OPTIND    OPTIND      OPTIND   1                        echo  Parsing option   --  OPTARG    value     val     gt  amp 2                                         loglevel                        val   OPTARG                         opt   OPTARG   val                      echo  Parsing option   --  opt    value     val     gt  amp 2                                                               if     OPTERR    1    amp  amp       optspec 0 1             then                         echo  Unknown option --  OPTARG    gt  amp 2                     fi                                    esac           h              echo  usage   0  -v   --loglevel    lt value gt     gt  amp 2             exit 2                        v              echo  Parsing option   -  optchar     gt  amp 2                                       if     OPTERR     1           optspec 0 1            then                 echo  Non-option argument   -  OPTARG     gt  amp 2             fi                    esac done   After copying to executable file name getopts test sh in the current working directory  one can produce output like      getopts test sh     getopts test sh -f Non-option argument   -f      getopts test sh -h usage  code getopts test sh  -v   --loglevel    lt value gt       getopts test sh --help     getopts test sh -v Parsing option   -v      getopts test sh --very-bad     getopts test sh --loglevel Parsing option   --loglevel   value         getopts test sh --loglevel 11 Parsing option   --loglevel   value   11      getopts test sh --loglevel 11 Parsing option   --loglevel   value   11    Obviously getopts neither performs OPTERR checking nor option-argument parsing for the long options  The script fragment above shows how this may be done manually  The basic principle also works in the Debian Almquist shell   dash    Note the special case   getopts --  -       without the option terminator  --   bash complains about  -   getopts  -          this works in the Debian Almquist shell   dash     Note that  as GreyCat from over at http   mywiki wooledge org BashFAQ points out  this trick exploits a non-standard behaviour of the shell which permits the option-argument  i e  the filename in  -f filename   to be concatenated to the option  as in  -ffilename    The POSIX standard says there must be a space between them  which in the case of  -- longoption  would terminate the option-parsing and turn all longoptions into non-option arguments

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There are three implementations that may be considered    Bash builtin getopts  This does not support long option names with the double-dash prefix   It only supports single-character options  BSD UNIX implementation of standalone getopt command  which is what MacOS uses   This does not support long options either  GNU implementation of standalone getopt   GNU getopt 3   used by the command-line getopt 1  on Linux  supports parsing long options        Some other answers show a solution for using the bash builtin getopts to mimic long options  That solution actually makes a short option whose character is  -   So you get  --  as the flag  Then anything following that becomes OPTARG  and you test the OPTARG with a nested case   This is clever  but it comes with caveats     getopts can t enforce the opt spec  It can t return errors if the user supplies an invalid option  You have to do your own error-checking as you parse OPTARG  OPTARG is used for the long option name  which complicates usage when your long option itself has an argument  You end up having to code that yourself as an additional case    So while it is possible to write more code to work around the lack of support for long options  this is a lot more work and partially defeats the purpose of using a getopt parser to simplify your code

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I only write shell scripts now and then and fall out of practice  so any feedback is appreciated   Using the strategy proposed by  Arvid Requate  we noticed some user errors  A user who forgets to include a value will accidentally have the next option s name treated as a value     getopts test sh --loglevel  --toc TRUE   will cause the value of  loglevel  to be seen as  --toc TRUE   This can be avoided   I adapted some ideas about checking user error for CLI from  http   mwiki wooledge org BashFAQ 035 discussion of manual parsing  I inserted error checking into handling both  -  and  --  arguments    Then I started fiddling around with the syntax  so any errors in here are strictly my fault  not the original authors    My approach helps users who prefer to enter long with or without the equal sign  That is  it should have same response to  --loglevel 9  as  --loglevel 9   In the -- space method  it is not possible to know for sure if the user forgets an argument  so some guessing is needed     if the user has the long equal sign format  --opt    then a space after   triggers an error because an argument was not supplied    if user has long space arguments  --opt    this script causes a fail if no argument follows  end of command  or if argument begins with dash    In case you are starting out on this  there is an interesting difference between  --opt value  and  --opt value  formats  With the equal sign  the command line argument is seen as  opt value  and the work to handle that is string parsing  to separate at the       In contrast  with  --opt value   the name of the argument is  opt  and we have the challenge of getting the next value supplied in the command line   That s where  Arvid Requate used    OPTIND   the indirect reference  I still don t understand that  well  at all  and comments in BashFAQ seem to warn against that style  http   mywiki wooledge org BashFAQ 006   BTW  I don t think previous poster s comments about importance of  OPTIND      OPTIND   1    are correct  I mean to say  I see no harm from omitting it   In newest version of this script  flag -v means VERBOSE printout    Save it in a file called  cli-5 sh   make executable  and any of these will work  or fail in the desired way    cli-5 sh  -v --loglevel 44 --toc  TRUE   cli-5 sh  -v --loglevel 44 --toc TRUE   cli-5 sh --loglevel 7   cli-5 sh --loglevel 8   cli-5 sh -l9    cli-5 sh  --toc FALSE --loglevel 77   cli-5 sh  --toc FALSE --loglevel 77    cli-5 sh   -l99 -t yyy   cli-5 sh   -l 99 -t yyy   Here is example output of the error-checking on user intpu      cli-5 sh  --toc --loglevel 77 ERROR  toc value must not have dash at beginning     cli-5 sh  --toc  --loglevel 77 ERROR  value for toc undefined   You should consider turning on -v  because it prints out internals of OPTIND and OPTARG    usr bin env bash     Paul Johnson    20171016        Combines ideas from    https   stackoverflow com questions 402377 using-getopts-in-bash-shell-script-to-get-long-and-short-command-line-options    by  Arvid Requate  and http   mwiki wooledge org BashFAQ 035    What I don t understand yet     In  Arvid REquate s answer  we have    val     OPTIND    OPTIND      OPTIND   1      this works  but I don t understand it    die         printf   s n    1   gt  amp 2     exit 1    printparse        if     VERBOSE  -gt 0    then         printf  Parse   s s s n    1    2    3   gt  amp 2      fi    showme        if     VERBOSE  -gt 0    then         printf  VERBOSE   s n    1   gt  amp 2      fi     VERBOSE 0 loglevel 0 toc  TRUE   optspec   vhl t -   while getopts   optspec  OPTCHAR  do      showme  OPTARG     OPTARG          showme  OPTIND     OPTIND          case    OPTCHAR   in         -              case    OPTARG   in                 loglevel   argument has no equal sign                     opt   OPTARG                      val     OPTIND                          check value  If negative  assume user forgot value                     showme  OPTIND is   OPTIND    OPTIND  has value      OPTIND                         if      val     -      then                         die  ERROR   opt value must not have dash at beginning                      fi                        OPTIND      OPTIND   1      CAUTION  no effect                      printparse  --  OPTARG           val                       loglevel    val                       shift                                        loglevel     argument has equal sign                     opt   OPTARG                         val   OPTARG                         if      OPTARG         then                         printparse  --  opt          val                           loglevel    val                              shift CAUTION don t shift this  fails othewise                     else                         die  ERROR   opt value must be supplied                      fi                                        toc   argument has no equal sign                     opt   OPTARG                      val     OPTIND                          check value  If negative  assume user forgot value                     showme  OPTIND is   OPTIND    OPTIND  has value      OPTIND                         if      val     -      then                         die  ERROR   opt value must not have dash at beginning                      fi                        OPTIND      OPTIND   1                            printparse  --  opt          val                       toc    val                       shift                                        toc     argument has equal sign                     opt   OPTARG                         val   OPTARG                         if      OPTARG         then                         toc   val                          printparse  -- opt    - gt      toc                            shift    NO  dont shift this                     else                         die  ERROR  value for  opt undefined                      fi                                         help                      echo  usage   0  -v   --loglevel    lt value gt    --toc    lt TRUE FALSE gt     gt  amp 2                     exit 2                                                               if     OPTERR    1    amp  amp       optspec 0 1             then                         echo  Unknown option --  OPTARG    gt  amp 2                     fi                                    esac           h -   --help                 must rewrite this for all of the arguments             echo  usage   0  -v   --loglevel    lt value gt    --toc    lt TRUE FALSE gt     gt  amp 2             exit 2                        l              loglevel   OPTARG              printparse  -l          loglevel                          t              toc   OPTARG                         v              VERBOSE 1                                        if     OPTERR     1           optspec 0 1            then                 echo  Non-option argument   -  OPTARG     gt  amp 2             fi                    esac done    echo   After Parsing values   echo  loglevel   loglevel   echo  toc   toc

User · Answer

There are three implementations that may be considered    Bash builtin getopts  This does not support long option names with the double-dash prefix   It only supports single-character options  BSD UNIX implementation of standalone getopt command  which is what MacOS uses   This does not support long options either  GNU implementation of standalone getopt   GNU getopt 3   used by the command-line getopt 1  on Linux  supports parsing long options        Some other answers show a solution for using the bash builtin getopts to mimic long options  That solution actually makes a short option whose character is  -   So you get  --  as the flag  Then anything following that becomes OPTARG  and you test the OPTARG with a nested case   This is clever  but it comes with caveats     getopts can t enforce the opt spec  It can t return errors if the user supplies an invalid option  You have to do your own error-checking as you parse OPTARG  OPTARG is used for the long option name  which complicates usage when your long option itself has an argument  You end up having to code that yourself as an additional case    So while it is possible to write more code to work around the lack of support for long options  this is a lot more work and partially defeats the purpose of using a getopt parser to simplify your code

[bash] Using getopts to process long and short command line options

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