Extract filename and extension in Bash

Question

I want to get the filename  without extension  and the extension separately   The best solution I found so far is   NAME  echo   FILE    cut -d    -f1  EXTENSION  echo   FILE    cut -d    -f2    This is wrong because it doesn t work if the file name contains multiple   characters  If  let s say  I have a b js  it will consider a and b js  instead of a b and js   It can be easily done in Python with  file  ext   os path splitext path    but I d prefer not to fire up a Python interpreter just for this  if possible   Any better ideas

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A simple bash one liner  I used this to remove rst extension from all files in pwd  for each in  ls -1   rst  do      a   echo  each   wc -c       echo  each   cut -c -     a-5     gt  gt  blognames done   What it does    1  ls -1   rst will list all the files on stdout in new line  try    2  echo  each   wc -c counts the number of characters in each filename    3  echo  each   cut -c -     a-5    selects up to last 4 characters  i e   rst

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You can use basename   Example     basename foo-bar tar gz  tar gz foo-bar   You do need to provide basename with the extension that shall be removed  however if you are always executing tar with -z then you know the extension will be  tar gz   This should do what you want   tar -zxvf  1 cd   basename  1  tar gz

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How to extract the filename and extension in fish   function split-filename-extension --description  Prints the filename and extension    for file in  argv     if test -f  file       set --local extension  echo  file   awk -F    print  NF          set --local filename  basename  file   extension        echo   filename  extension      else       echo   file is not a valid file      end   end end   Caveats  Splits on the last dot  which works well for filenames with dots in them  but not well for extensions with dots in them  See example below   Usage     split-filename-extension foo-0 4 2 zip bar tar gz foo-0 4 2 zip    Looks good  bar tar gz    Careful  you probably want  tar gz as the extension    There s probably better ways to do this  Feel free to edit my answer to improve it     If there s a limited set of extensions you ll be dealing with and you know all of them  try this   switch  file   case   tar     echo  basename  file  tar  tar   case   tar bz2     echo  basename  file  tar bz2  tar bz2   case   tar gz     echo  basename  file  tar gz  tar gz     and so on end   This does not have the caveat as the first example  but you do have to handle every case so it could be more tedious depending on how many extensions you can expect

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You can use the magic of POSIX parameter expansion   bash-3 2  FILENAME somefile tar gz bash-3 2  echo    FILENAME       somefile bash-3 2  echo    FILENAME      somefile tar     There s a caveat in that if your filename was of the form   somefile tar gz then echo   FILENAME      would greedily remove the longest match to the   and you d have the empty string     You can work around that with a temporary variable   FULL FILENAME  FILENAME FILENAME   FULL FILENAME      echo   FILENAME             This site explains more     variable pattern    Trim the shortest match from the end   variable  pattern    Trim the longest match from the beginning   variable  pattern    Trim the longest match from the end   variable pattern    Trim the shortest match from the beginning

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Simply use   parameter word   In your case     FILE       If you want to test it  all following work  and just remove the extension   FILE abc xyz  echo   FILE      FILE 123 abc xyz  echo   FILE      FILE abc  echo   FILE

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No need to bother with awk or sed or even perl for this simple task  There is a pure-Bash  os path splitext  -compatible solution which only uses parameter expansions   Reference Implementation  Documentation of os path splitext path       Split the pathname path into a pair  root  ext  such that root   ext    path  and ext is empty or begins with a period and contains at most one period  Leading periods on the basename are ignored  splitext   cshrc   returns    cshrc          Python code   root  ext   os path splitext path    Bash Implementation  Honoring leading periods  root    path      ext    path   root      Ignoring leading periods  root    path     root    path   root    root      ext    path   root      Tests  Here are test cases for the Ignoring leading periods implementation  which should match the Python reference implementation on every input    --------------- ----------- -------   path            root        ext       --------------- ----------- -------      txt                        txt        txt txt         txt        txt       txt             txt                    txt txt         txt        txt       cshrc           cshrc                 txt             txt                    txt txt         txt        txt       n txt txt       n txt       txt       t txt txt       t txt       txt      a b txt txt     a b txt      txt      a b txt txt     a b txt      txt      a b txt txt     a b txt      txt      a nb txt txt    a nb txt     txt      a tb txt txt    a tb txt     txt      txt             txt                   txt pdf         txt          pdf      txt tar gz      txt tar      gz       txt txt         txt          txt     --------------- ----------- -------    Test Results  All tests passed

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From the answers above  the shortest oneliner to mimic Python s  file  ext   os path splitext path    presuming your file really does have an extension  is  EXT    PATH        FILE   basename   PATH    EXT

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Smallest and simplest solution  in single line  is     file  blaabla bla blah foo txt echo   basename   file        foo

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You could use the cut command to remove the last two extensions  the   tar gz  part      echo  foo tar gz    cut -d    --complement -f2- foo     As noted by Clayton Hughes in a comment  this will not work for the actual example in the question  So as an alternative I propose using sed with extended regular expressions  like this     echo  mpc-1 0 1 tar gz    sed -r  s      alnum         alnum         mpc-1 0 1   It works by removing the last two  alpha-numeric  extensions unconditionally    Updated again after comment from Anders Lindahl

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Usually you already know the extension  so you might wish to use   basename filename  extension   for example   basename  path to dir filename txt  txt   and we get  filename

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The accepted answer works well in typical cases  but fails in edge cases  namely    For filenames without extension  called suffix in the remainder of this answer   extension   filename      returns the input filename rather than an empty string  extension   filename      does not include the initial    contrary to convention    Blindly prepending   would not work for filenames without suffix   filename    filename      will be the empty string  if the input file name starts with   and contains no further   characters  e g    bash profile  - contrary to convention     ---------  Thus  the complexity of a robust solution that covers all edge cases calls for a function - see its definition below  it can return all components of a path   Example call   splitPath   etc bash bashrc  dir fname fnameroot suffix   - gt   dir      etc    - gt   fname     bash bashrc    - gt   fnameroot     bash    - gt   suffix      bashrc    Note that the arguments after the input path are freely chosen  positional variable names  To skip variables not of interest that come before those that are  specify    to use throw-away variable     or     e g   to extract filename root and extension only  use splitPath   etc bash bashrc      fnameroot extension       SYNOPSIS     splitPath path varDirname  varBasename  varBasenameRoot  varSuffix       DESCRIPTION     Splits the specified input path into its components and returns them by assigning     them to variables with the specified  names       Specify    or throw-away variable   to skip earlier variables  if necessary      The filename suffix  if any  always starts with     - only the  last         -prefixed token is reported as the suffix      As with  dirname   varDirname will report      current dir  for input paths     that are mere filenames  and     for the root dir      As with  dirname  and  basename   a trailing     in the input path is ignored      A     as the very first char  of a filename is NOT considered the beginning     of a filename suffix    EXAMPLE     splitPath   home jdoe readme txt  parentpath fname fnameroot suffix     echo   parentpath    - gt    home jdoe      echo   fname    - gt   readme txt      echo   fnameroot    - gt   readme      echo   suffix    - gt    txt      ---     splitPath   home jdoe readme txt      fnameroot     echo   fnameroot    - gt   readme    splitPath       local  sp dirname   sp basename   sp basename root   sp suffix        simple argument validation          gt   2         echo   FUNCNAME  ERROR  Specify an input path and at least 1 output variable name    gt  amp 2  exit 2          extract dirname  parent path  and basename  filename     sp dirname   dirname   1      sp basename   basename   1         determine suffix  if any    sp suffix        sp basename           amp  amp  printf  s      sp basename          printf           determine basename root  filemane w o suffix    if       sp basename        sp suffix      then   does filename start with             sp basename root   sp basename        sp suffix      else   strip suffix from filename      sp basename root    sp basename   sp suffix    fi     assign to output vars       -n  2     amp  amp  printf -v   2     sp dirname       -n  3     amp  amp  printf -v   3     sp basename       -n  4     amp  amp  printf -v   4     sp basename root       -n  5     amp  amp  printf -v   5     sp suffix    return 0    test paths       etc bash bashrc      usr bin grep      Users jdoe  bash profile      Library Application Support      readme new txt     for p in    test paths       do   echo -----   p    parentpath  fname  fnameroot  suffix    splitPath   p  parentpath fname fnameroot suffix   for n in parentpath fname fnameroot suffix  do     echo   n    n     done done   Test code that exercises the function   test paths       etc bash bashrc      usr bin grep      Users jdoe  bash profile      Library Application Support      readme new txt     for p in    test paths       do   echo -----   p    parentpath  fname  fnameroot  suffix    splitPath   p  parentpath fname fnameroot suffix   for n in parentpath fname fnameroot suffix  do     echo   n    n     done done   Expected output - note the edge cases    a filename having no suffix a filename starting with    not considered the start of the suffix  an input path ending in    trailing   is ignored  an input path that is a filename only    is returned as the parent path  a filename that has more than  -prefixed token  only the last is considered the suffix     -----  etc bash bashrc parentpath  etc fname bash bashrc fnameroot bash suffix  bashrc -----  usr bin grep parentpath  usr bin fname grep fnameroot grep suffix  -----  Users jdoe  bash profile parentpath  Users jdoe fname  bash profile fnameroot  bash profile suffix  -----  Library Application Support  parentpath  Library fname Application Support fnameroot Application Support suffix  ----- readme new txt parentpath   fname readme new txt fnameroot readme new suffix  txt

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This is the only one that worked for me   path  folder other folder file js   base   path      echo   base       gt  gt  file   This can also be used in string interpolation as well  but unfortunately you have to set base beforehand

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You can also use a for loop and tr to extract the filename from the path     for x in  echo  path   tr           do filename  x  done   The tr replaces all     delimiters in path with spaces so making a list of strings  and the for loop scans through them leaving the last one in the filename variable

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Magic file recognition  In addition to the lot of good answers on this Stack nbsp Overflow question I would like to add   Under Linux and other unixen  there is a magic command named file  that do filetype detection by analysing some first bytes of file  This is a very old tool  initialy used for print servers  if not created for    I m not sure about that    file myfile txt myfile txt  UTF-8 Unicode text  file -b --mime-type myfile txt text plain   Standards extensions could be found in  etc mime types  on my Debian GNU Linux desktop  See man file and man mime types  Perhaps you have to install the file utility and mime-support packages    grep    file -b --mime-type myfile txt    lt  etc mime types text plain      asc txt text pot brf srt   You could create a bash function for determining right extension  There is a little  not perfect  sample   file2ext         local  mimetype   file -Lb --mime-type   1    line  basemimetype     case    mimetype      -   in         gzip   bzip2   xz   z                mimetype    mimetype      -                mimetype    mimetype  ip               basemimetype   file -zLb --mime-type   1                          stream                mimetype    file -Lb   1                      mimetype 1       compressed     amp  amp                   basemimetype   file -b --mime-type -  lt   lt                              mimetype    -d  lt   1                        basemimetype    mimetype                 mimetype    mimetype                           executable     mimetype     basemimetype               dosexec        mimetype     basemimetype  exe             shellscript    mimetype     basemimetype  sh                              basemimetype   mimetype              mimetype                       esac     while read -a  line  do         if      line        basemimetype     then                  line 1      amp  amp                   basemimetype    line 1                       basemimetype    basemimetype      -               break         fi         done  lt  etc mime types     case    basemimetype      -   in         executable    basemimetype               shellscript    basemimetype  sh             dosexec    basemimetype  exe                        esac          mimetype     amp  amp       basemimetype        mimetype     amp  amp        printf   2 -v   2   s  s     basemimetype      -      mimetype      -            printf   2 -v   2   s     basemimetype      -       This function could set a Bash variable that can be used later    This is inspired from  Petesh right answer    filename   basename   fullfile   filename    filename      file2ext   fullfile  extension  echo   fullfile - gt   filename    extension

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Here is the algorithm I used for finding the name and extension of a file when I wrote a Bash script to make names unique when names conflicted with respect to casing        bin bash       Finds    -- name and extension pairs   -- null extension when there isn t an extension    -- Finds name of a hidden file without an extension     declare -a fileNames       Montreal       Rome txt      Loundon txt      Paris      San Diego txt     San Francisco        echo  Script   0  finding name and extension pairs   echo   for theFileName in    fileNames      do      echo  theFileName   theFileName             Get the proposed name by chopping off the extension      name    theFileName              get extension   Set to null when there isn t an extension        Thanks to mklement0 in a comment above       extension        theFileName             amp  amp  echo     theFileName          echo             a hidden file without extenson       if      theFileName        extension       then            hidden file without extension   Fixup           name   theFileName           extension         fi       echo    name   name        echo    extension   extension   done    The test run     config Name  amp Extension bash  Script config Name amp Extension bash finding name and extension pairs   theFileName  Montreal   name  Montreal   extension  theFileName  Rome txt   name  Rome   extension  txt theFileName Loundon txt   name Loundon   extension  txt theFileName Paris   name Paris   extension  theFileName San Diego txt   name San Diego   extension  txt theFileName San Francisco   name San Francisco   extension       FYI  The complete transliteration program and more test cases can be found here  https   www dropbox com s 4c6m0f2e28a1vxf avoid-clashes-code zip dl 0

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Here is code with AWK  It can be done more simply  But I am not good in AWK   filename  ls abc a txt  a b c txt  pp-kk txt filename  find   -type f   awk -F    print  2     rev   awk -F       1    print     rev   awk  gsub           sub            abc a a b c pp-kk filename  find   -type f   awk -F    print  2     awk -F      print  NF   txt txt txt

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Mellen writes in a comment on a blog post   Using Bash  there   s also   file     to get the filename without the extension and   file      to get the extension alone  That is   file  thisfile txt  echo  filename    file      echo  extension    file         Outputs   filename  thisfile extension  txt

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pax gt  echo a b js   sed  s             a b pax gt  echo a b js   sed  s          js   works fine  so you can just use   pax gt  FILE a b js pax gt  NAME   echo   FILE    sed  s              pax gt  EXTENSION   echo   FILE    sed  s           pax gt  echo  NAME a b pax gt  echo  EXTENSION js   The commands  by the way  work as follows   The command for NAME substitutes a     character followed by any number of non-    characters up to the end of the line  with nothing  i e   it removes everything from the final     to the end of the line  inclusive   This is basically a non-greedy substitution using regex trickery   The command for EXTENSION substitutes a any number of characters followed by a     character at the start of the line  with nothing  i e   it removes everything from the start of the line to the final dot  inclusive   This is a greedy substitution which is the default action

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IMHO the best solution has already been given  using shell parameter expansion  and are the best rated one at this time   I however add this one which just use dumbs commands  which is not efficient and which noone serious should use ever    FILENAME   echo  FILE   cut -d   -f 1-  printf  FILE   tr     n    wc -l   EXTENSION   echo  FILE   tr     n    tail -1    Added just for fun  -

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In order to make dir more useful  in the case a local file with no path is specified as input  I did the following     Substring from 0 thru pos of filename dir    fullpath 0    fullpath  -    filename    if    -z   dir      then     dir      fi   This allows you to do something useful like add a suffix to the input file basename as   outfile   dir   base  suffix   ext   testcase  foo bar dir       base   foo  ext   bar  outfile     foo suffix bar   testcase   home me foo bar dir    home me   base   foo  ext   bar  outfile    home me foo suffix bar

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Based largely off of  mklement0 s excellent  and chock-full of random  useful bashisms - as well as other answers to this   other questions    that darn internet     I wrapped it all up in a little  slightly more comprehensible  reusable function for my  or your   bash profile that takes care of what  I consider  should be a more robust version of dirname basename   what have you    function path   SAVEIFS  IFS  IFS        stash IFS for safe-keeping  etc               2     amp  amp  echo  usage  path  lt path gt   lt dir name fullname ext gt    amp  amp  return      demand 2 arguments         1                      amp  amp          regex parse the path         dir   BASH REMATCH 1           file   BASH REMATCH 2           ext       file           amp  amp  printf  s   file         printf               edge cases for extensionless files and files like   nesh profile coffee              file     ext     amp  amp  fnr  file  amp  amp  ext       fnr   file 0       file -   ext             case   2  in              dir  echo         dir                      name  echo         fnr                  fullname  echo    fnr      ext                   ext  echo             ext              esac           IFS  SAVEIFS          Usage examples     SOMEPATH  path to some  random  file gzip path  SOMEPATH dir           path to some path  SOMEPATH name          random file path  SOMEPATH ext          gzip path  SOMEPATH fullname      random file gzip                      path gobbledygook           usage  -bash  lt path gt   lt dir name fullname ext gt

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First  get file name without the path   filename   basename --   fullfile   extension    filename       filename    filename        Alternatively  you can focus on the last     of the path instead of the     which should work even if you have unpredictable file extensions   filename    fullfile         You may want to check the documentation     On the web at section  3 5 3 Shell Parameter Expansion  In the bash manpage at section called  Parameter Expansion

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Here are some alternative suggestions  mostly in awk   including some advanced use cases  like extracting version numbers for software packages     f   path to complex file 1 0 1 tar gz     Filename    file 1 0 x tar gz      echo   f    awk -F      print  NF      Extension  last    gz      echo   f    awk -F        print  NF      Extension  all     1 0 1 tar gz      echo   f    awk   sub                  0   1     Extension  last-2    tar gz      echo   f    awk -F        print   NF-1     NF      Basename    file      echo   f    awk   gsub                     0   1     Basename-extended    file 1 0 1 tar      echo   f    awk   gsub            1               0   1     Path     path to complex       echo   f    awk   match  0           a   print a 0          or      echo   f    grep -Eo            Folder  containing the file     complex      echo   f    awk -F       1     print   NF-1       Version    1 0 1        Defined as  number number  or  number number number      echo   f    grep -Eo   0-9       0-9       0-9           Version - major    1      echo   f    grep -Eo   0-9       0-9       0-9      cut -d  -f1        Version - minor    0      echo   f    grep -Eo   0-9       0-9       0-9      cut -d  -f2        Version - patch    1      echo   f    grep -Eo   0-9       0-9       0-9      cut -d  -f3    All Components    path to complex file 1 0 1 tar gz      echo   f    awk -F          1     print  0      Is absolute   True  exit-code   0        Return true if it is an absolute path  starting with     or          echo   f    grep -q               All use cases are using the original full path as input  without depending on intermediate results

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You can use  sed  s         rev   cut -d  -f2-   rev   cut -c2-   to get file name and  sed  s         rev   cut -d  -f1    rev   to get extension   Test case   echo  filename gz        sed  s         rev   cut -d  -f2-   rev   cut -c2- echo  filename gz        sed  s         rev   cut -d  -f1    rev echo  filename           sed  s         rev   cut -d  -f2-   rev   cut -c2- echo  filename           sed  s         rev   cut -d  -f1    rev echo  filename tar gz    sed  s         rev   cut -d  -f2-   rev   cut -c2- echo  filename tar gz    sed  s         rev   cut -d  -f1    rev

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I use the following script    echo  foo tar gz  rev cut -d    -f3- rev foo

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Ok so if I understand correctly  the problem here is how to get the name and the full extension of a file that has multiple extensions  e g   stuff tar gz   This works for me   fullfile  stuff tar gz  fileExt   fullfile     fileName   fullfile    fileExt    This will give you stuff as filename and  tar gz as extension  It works for any number of extensions  including 0  Hope this helps for anyone having the same problem

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Using example file  Users Jonathan Scripts bash MyScript sh  this code   MY EXT     0       ME    usr bin basename    0      MY EXT      will result in   ME  being MyScript and   MY EXT  being  sh     Script      bin bash set -e  MY EXT     0       ME    usr bin basename    0      MY EXT     echo    ME  -   MY EXT     Some tests       MyScript sh  MyScript -  sh    bash MyScript sh MyScript -  sh     Users Jonathan Scripts bash MyScript sh MyScript -  sh    bash  Users Jonathan Scripts bash MyScript sh MyScript -  sh

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You can force cut to display all fields and subsequent ones adding - to field number   NAME  basename   FILE   EXTENSION  echo   NAME    cut -d    -f2-    So if FILE is eth0 pcap gz  the EXTENSION will be pcap gz  Using the same logic  you can also fetch the file name using  -  with cut as follows    NAME  basename   FILE    cut -d    -f-1    This works even for filenames that do not have any extension

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Building from Petesh answer  if only the filename is needed  both path and extension can be stripped in a single line   filename   basename   fullname

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I think that if you just need the name of the file  you can try this   FULLPATH  usr share X11 xorg conf d 50-synaptics conf    Remove all the prefix until the     character FILENAME   FULLPATH         Remove all the prefix until the     character FILEEXTENSION   FILENAME         Remove a suffix  in our case  the filename  This will return the name of the directory that contains this file  BASEDIRECTORY   FULLPATH  FILENAME   echo  path    FULLPATH  echo  file name    FILENAME  echo  file extension    FILEEXTENSION  echo  base directory    BASEDIRECTORY    And that is all  D

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FILE  example tar gz      echo    FILE       example     echo    FILE      example tar     echo    FILE      tar gz     echo    FILE       gz   For more details  see shell parameter expansion in the Bash manual

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Maybe there is an option in tar to do this  did you check the man  Otherwise  you can use Bash string expansion   test  mpc-1 0 1 tar gz  noExt    test  tar gz      Remove the string   tar gz  echo  noExt

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A simple answer   To expand on the POSIX variables answer  note that you can do more interesting patterns  So for the case detailed here  you could simply do this   tar -zxvf  1 cd   1  tar      That will cut off the last occurrence of  tar  lt something gt    More generally  if you wanted to remove the last occurrence of   lt something gt   lt something-else gt  then    1        should work fine   The link the above answer appears to be dead  Here s a great explanation of a bunch of the string manipulation you can do directly in Bash  from TLDP

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That doesn t seem to work if the file has no extension  or no filename   Here is what I m using  it only uses builtins and handles more  but not all  pathological filenames      bin bash for fullpath in      do     filename    fullpath                              Strip longest match of    from start     dir    fullpath 0    fullpath  -    filename      Substring from 0 thru pos of filename     base    filename                                  Strip shortest match of   plus at least one non-dot char from end     ext    filename    base    1                      Substring from len of base thru end     if    -z   base   amp  amp  -n   ext      then            If we have an extension and no base  it s really the base         base    ext          ext        fi      echo -e   fullpath  n tdir       dir   n tbase      base   n text       ext    done   And here are some testcases      basename-and-extension sh    home me   home me file  home me file tar  home me file tar gz  home me  hidden  home me  hidden tar  home me             dir            base          ext        home me       dir      home me       base          ext        home me file      dir      home me       base    file      ext        home me file tar      dir      home me       base    file      ext     tar   home me file tar gz      dir      home me       base    file tar      ext     gz   home me  hidden      dir      home me       base     hidden      ext        home me  hidden tar      dir      home me       base     hidden      ext     tar   home me         dir      home me       base            ext              dir           base           ext

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Here is a sed solution that extracts path components in a variety of forms and can handle most edge cases      Enter the input path and field separator character  for example      separatorChar must not be present in inputPath   inputPath   path to Foo bar  separatorChar         sed extracts the path components and assigns them to output variables  oldIFS   IFS  IFS   separatorChar  read dirPathWithSlash dirPath fileNameWithExt fileName fileExtWithDot fileExt  lt  lt  lt    sed -En   s     space       s    space        t l1  l1 s             t s         t l2  l2 s    filesystem    filesystem p t h s                     1 2   1   3 p g t l3  l3 s                     a-zA-Z0-9      1   2 3   3 p t s              1 p    lt  lt  lt   inputPath    tr   n    separatorChar    IFS   oldIFS      Results  all use separatorChar          inputPath           path to Foo bar    dirPathWithSlash    path to     dirPath             path to     fileNameWithExt    Foo bar    fileName           Foo    fileExtWithDot      bar    fileExt            bar     inputPath           path to Foobar    dirPathWithSlash    path to     dirPath             path to     fileNameWithExt    Foobar    fileName           Foobar    fileExtWithDot        fileExt                inputPath           path to    bar    dirPathWithSlash    path to     dirPath             path to     fileNameWithExt       bar    fileName                 fileExtWithDot      bar    fileExt            bar     inputPath           path to   bar    dirPathWithSlash    path to     dirPath             path to     fileNameWithExt      bar    fileName                fileExtWithDot      bar    fileExt            bar     inputPath           path to  bar    dirPathWithSlash    path to     dirPath             path to     fileNameWithExt     bar    fileName            bar    fileExtWithDot         fileExt                 inputPath           path to        dirPathWithSlash    path to     dirPath             path to     fileNameWithExt           fileName                  fileExtWithDot        fileExt                inputPath           path to Foo     dirPathWithSlash    path to     dirPath             path to     fileNameWithExt    Foo     fileName           Foo     fileExtWithDot        fileExt                inputPath             the root directory     dirPathWithSlash   filesystem     dirPath            filesystem    fileNameWithExt       fileName              fileExtWithDot        fileExt                inputPath            invalid because empty     dirPathWithSlash      dirPath               fileNameWithExt       fileName              fileExtWithDot        fileExt                inputPath          Foo bar  invalid because doesn t start with a forward slash     dirPathWithSlash      dirPath               fileNameWithExt       fileName              fileExtWithDot        fileExt              Here s how it works   sed parses the input path and prints the following path components in order on separate lines    directory path with a trailing slash character directory path without a trailing slash character file name with extension file name without extension file extension with a leading dot character file extension without a leading dot character   tr converts the sed output into a separator character-delimited string of the above path components   read uses the separator character as the field separator  IFS   separatorChar   and assigns each of the path components to its respective variable   Here s how the sed construct works    s     space       and s    space        strip any leading and or trailing whitespace characters t l1 and  l1 refreshes the t function for the next s function s             and t tests for an invalid input path  one that does not begin with a forward slash   in which case it leaves all output lines blank and quits the sed command s         strips any trailing slashes t l2 and  l2 refreshes the t function for the next s function s    filesystem     newline filesystem p and t tests for the special case where the input path consists of the root directory    in which case it prints filesystem  and filesystem for the dirPathWithSlash and dirPath output lines  leaves all other output lines blank  and quits the sed command h saves the input path in the hold space s                     1 2   newline  1   newline  3 p prints the dirPathWithSlash  dirPath  and fileNameWithExt output lines g retrieves the input path from the hold space t l3 and  l3 refreshes the t function for the next s function s                      a-zA-Z0-9      1   newline  2 3   newline  3 p and t prints the fileName  fileExtWithDot  and fileExt output lines for the case where a file extension exists   assumed to consist of alphanumeric characters only   then quits the sed command s               1 p prints the fileName but not the fileExtWithDot  and fileExt output lines for the case where a file extension does not exist  then quits the sed command

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F    text file test txt      echo   F        txt     This caters for multiple dots and spaces in a filename  however if there is no extension it returns the filename itself  Easy to check for though  just test for the filename and extension being the same   Naturally this method doesn t work for  tar gz files  However that could be handled in a two step process  If the extension is gz then check again to see if there is also a tar extension

User · Answer

If you also want to allow empty extensions  this is the shortest I could come up with   echo  hello txt    sed -r  s              1     EXTENSION echo  hello txt    sed -r  s                1 2     FILENAME   1st line explained  It matches PATH EXT or ANYTHING and replaces it with EXT  If ANYTHING was matched  the ext group is not captured

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