How do I prompt for Yes No Cancel input in a Linux shell script

Question

I want to pause input in a shell script  and prompt the user for choices  The standard Yes  No  or Cancel type question  How do I accomplish this in a typical bash prompt

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This solution reads a single character and calls a function on a yes response   read -p  Are you sure   y n    -n 1 echo if     REPLY      Yy       then     do something       fi

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yn       if     y      read -s -n 1 -p   y n     Y  echo  Y        then eval  1    else eval  2    fi   yn  echo yes   echo no  yn  echo absent no function works too

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I noticed that no one posted an answer showing multi-line echo menu for such simple user input so here is my go at it      bin bash  function ask user          echo -e                    1   Yes        2   No         3   Quit                    n   read -e -p  Select 1    choice  if     choice      1     then      do something  elif     choice      2     then      do something else  elif     choice      3     then      clear  amp  amp  exit 0  else      echo  Please select 1  2  or 3    amp  amp  sleep 3     clear  amp  amp  ask user  fi    ask user   This method was posted in the hopes that someone may find it useful and time-saving

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Use the read command   echo Would you like to install    Y or N    read x    now check if  x is  y  if     x     y     then       do something here  fi   and then all of the other stuff you need

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Inspired by the answers of  Mark and  Myrddin I created this function for a universal prompt  uniprompt        while true  do         echo -e   1 c          read opt         array   2          case    array      in     opt    eval   3  opt  return 0   esac         echo -e   opt is not a correct value n      done     use it like this   unipromtp  Select an option   a -Do one  x - gt Do two  f - gt Do three      a x f  selection echo   selection

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The simplest and most widely available method to get user input at a shell prompt is the read command  The best way to illustrate its use is a simple demonstration   while true  do     read -p  Do you wish to install this program   yn     case  yn in          Yy     make install  break            Nn     exit               echo  Please answer yes or no         esac done   Another method  pointed out by Steven Huwig  is Bash s select command  Here is the same example using select   echo  Do you wish to install this program   select yn in  Yes   No   do     case  yn in         Yes   make install  break           No   exit       esac done   With select you don t need to sanitize the input  ndash  it displays the available choices  and you type a number corresponding to your choice  It also loops automatically  so there s no need for a while true loop to retry if they give invalid input   Also  L  a Gris demonstrated a way to make the request language agnostic in her answer  Adapting my first example to better serve multiple languages might look like this   set --   locale LC MESSAGES  yesptrn   1   noptrn   2   yesword   3   noword   4   while true  do     read -p  Install    yesword      noword      yn     case  yn in           yesptrn       make install  break             noptrn       exit               echo  Answer   yesword      noword          esac done   Obviously other communication strings remain untranslated here  Install  Answer  which would need to be addressed in a more fully completed translation  but even a partial translation would be helpful in many cases   Finally  please check out the excellent answer by F  Hauri

User · Answer

The simplest and most widely available method to get user input at a shell prompt is the read command  The best way to illustrate its use is a simple demonstration   while true  do     read -p  Do you wish to install this program   yn     case  yn in          Yy     make install  break            Nn     exit               echo  Please answer yes or no         esac done   Another method  pointed out by Steven Huwig  is Bash s select command  Here is the same example using select   echo  Do you wish to install this program   select yn in  Yes   No   do     case  yn in         Yes   make install  break           No   exit       esac done   With select you don t need to sanitize the input  ndash  it displays the available choices  and you type a number corresponding to your choice  It also loops automatically  so there s no need for a while true loop to retry if they give invalid input   Also  L  a Gris demonstrated a way to make the request language agnostic in her answer  Adapting my first example to better serve multiple languages might look like this   set --   locale LC MESSAGES  yesptrn   1   noptrn   2   yesword   3   noword   4   while true  do     read -p  Install    yesword      noword      yn     case  yn in           yesptrn       make install  break             noptrn       exit               echo  Answer   yesword      noword          esac done   Obviously other communication strings remain untranslated here  Install  Answer  which would need to be addressed in a more fully completed translation  but even a partial translation would be helpful in many cases   Finally  please check out the excellent answer by F  Hauri

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To get a nice ncurses-like inputbox use the command dialog like this      bin bash if  dialog --title  Message  --yesno  Want to do something risky   6 25    message box will have the size 25x6 characters then      echo  Let s do something risky        do something risky else      echo  Let s stay boring  fi   The dialog package is installed by default at least with SUSE Linux  Looks like

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Multiple choice version   ask                                1 question  2 options       set REPLY       options  x    y        while   true   do         printf   s   s      1    2          stty cbreak         REPLY   dd if  dev tty bs 1 count 1 2 gt   dev null          stty -cbreak         test   REPLY        printf   n     amp  amp  printf   n                        IFS                 for o in  2  do                 if     REPLY       o          then                     printf   n                      break                 fi             done             grep    gt   dev null  amp  amp  return     done     Example     ask  continue    y yes n no m maybe  continue   y yes n no m maybe  g continue   y yes n no m maybe  k continue   y yes n no m maybe  y     It will set REPLY to y  inside the script

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echo  Please enter some input    read input variable echo  You entered   input variable

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At least five answers for one generic question   Depending on   posix compliant  could work on poor systems with generic shell environments bash specific  using so called bashisms   and if you want   simple   in line   question   answer  generic solutions  pretty formatted interfaces  like ncurses or more graphical using libgtk or libqt    use powerful readline history capability   1  POSIX generic solutions  You could use the read command  followed by if     then     else   echo -n  Is this a good question  y n     read answer       if echo   answer    grep -iq   y   then     if     answer        answer  Yy       then     echo Yes else     echo No fi    Thanks to Adam Katz s comment  Replaced the test above with one that is more portable and avoids one fork    POSIX  but single key feature  But if you don t want the user to have to hit Return  you could write    Edited  As  JonathanLeffler rightly suggest  saving stty s configuration could be better than simply force them to sane    echo -n  Is this a good question  y n     old stty cfg   stty -g  stty raw -echo   answer   head -c 1    stty  old stty cfg   Careful playing with stty if echo   answer    grep -iq   y   then     echo Yes else     echo No fi   Note  This was tested under sh  bash  ksh  dash and busybox   Same  but waiting explicitly for y or n     bin sh echo -n  Is this a good question  y n     old stty cfg   stty -g  stty raw -echo answer    while   head -c 1   grep -i   ny    do true  done   stty  old stty cfg if echo   answer    grep -iq   y   then     echo Yes else     echo No fi   Using dedicated tools  There are many tools which were built using libncurses  libgtk  libqt or other graphical libraries  For example  using whiptail   if whiptail --yesno  Is this a good question  20 60  then     echo Yes else     echo No fi   Depending on your system  you may need to replace whiptail with another similiar tool   dialog --yesno  Is this a good question  20 60  amp  amp  echo Yes  gdialog --yesno  Is this a good question  20 60  amp  amp  echo Yes  kdialog --yesno  Is this a good question  20 60  amp  amp  echo Yes   where 20 is height of dialog box in number of lines and 60 is width of  the dialog box  These tools all have near same syntax   DIALOG whiptail if   -x  usr bin gdialog    then DIALOG gdialog   fi if   -x  usr bin xdialog    then DIALOG xdialog   fi      DIALOG --yesno       2  Bash specific solutions  Basic in line method  read -p  Is this a good question  y n     answer case   answer 0 1  in     y Y           echo Yes                        echo No        esac   I prefer to use case so I could even test for yes   ja   si   oui if needed     in line with single key feature  Under bash  we can specify the length of intended input for for the read command   read -n 1 -p  Is this a good question  y n     answer   Under bash  read command accepts a timeout parameter  which could be useful   read -t 3 -n 1 -p  Is this a good question  y n     answer   -z   answer     amp  amp  answer  Yes     if  yes  have to be default choice   3   Some tricks for dedicated tools  More sophisticated dialog boxes  beyond simple yes - no purposes   dialog --menu  Is this a good question  20 60 12 y Yes n No m Maybe   Progress bar   dialog --gauge  Filling the tank  20 60 0  lt   lt       for i in  1  100  do         printf  XXX n d n   a  b  T T progress   d nXXX n   i -1  i         sleep  033     done      Little demo      bin sh while true  do       -x    which   DIALOG             DIALOG dialog     DIALOG    DIALOG --menu  Which tool for next run   20 60 12 2 gt  amp 1               whiptail        dialog boxes from shell scripts   gt  dev tty               dialog          dialog boxes from shell with ncurses                gdialog         dialog boxes from shell with Gtk                kdialog         dialog boxes from shell with Kde       exit     clear echo  Choosed   DIALOG       for i in  seq 1 100  do         date    printf  XXX n d n  a   b   T progress   d nXXX n   i  i           sleep  0125       done    DIALOG --gauge  Filling the tank  20 60 0      DIALOG --infobox  This is a simple info box n nNo action required  20 60     sleep 3     if  DIALOG --yesno   Do you like this demo   20 60  then         AnsYesNo Yes  else AnsYesNo No  fi     AnsInput    DIALOG --inputbox  A text   20 60  Text here     2 gt  amp 1  gt  dev tty      AnsPass    DIALOG --passwordbox  A secret   20 60  First     2 gt  amp 1  gt  dev tty       DIALOG --textbox  etc motd 20 60     AnsCkLst    DIALOG --checklist  Check some     20 60 12           Correct  This demo is useful         off           Fun         This demo is nice         off           Strong         This demo is complex         on 2 gt  amp 1  gt  dev tty      AnsRadio    DIALOG --radiolist  I will   20 60 12             -1   Downgrade this answer         off              0   Not do anything                 on              1   Upgrade this anser         off 2 gt  amp 1  gt  dev tty      out  Your answers  nLike   AnsYesNo nInput   AnsInput nSecret   AnsPass       DIALOG --msgbox   out nAttribs   AnsCkLst nNote   AnsRadio  20 60   done   More sample  Have a look at Using whiptail for choosing USB device and USB removable storage selector  USBKeyChooser  5  Using readline s history  Example      bin bash  set -i HISTFILE    myscript history history -c history -r  myread         read -e -p   gt     1     history -s    1    trap  history -a exit  0 1 2 3 6  while myread line do     case   line      in         exit    break                    echo  Doing something with   line            esac   done   This will create a file  myscript history in your  HOME directory  than you could use readline s history commands  like Up   Down  Ctrl r and others

User · Answer

Here s something I put together      bin sh  promptyn          while true  do         read -p   1   yn         case  yn in              Yy     return 0                Nn     return 1                   echo  Please answer yes or no             esac     done    if promptyn  is the sky blue    then     echo  yes  else     echo  no  fi   I m a beginner  so take this with a grain of salt  but it seems to work

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I ve used the case statement a couple of times in such a scenario  using the case statment is a good way to go about it  A while loop  that ecapsulates the case block  that utilizes a boolean condition can be implemented in order to hold even more control of the program  and fulfill many other requirements  After the all the conditions have been met  a break can be used which will pass control back to the main part of the program  Also  to meet other conditions  of course conditional statements can be added to accompany the control structures  case statement and possible while loop   Example of using a case statement to fulfill your request      bin sh     For potential users of BSD  or other systems who do not   have a bash binary located in  bin the script will be directed to   a bourne-shell  e g   bin sh    NOTE  It would seem best for handling user entry errors or   exceptions  to put the decision required by the input    of the prompt in a case statement  case control structure     echo Would you like us to perform the option    Y N    read inPut  case  inPut in       echoing a command encapsulated by        backticks      executes the command      Y   echo  Do something crazy               depending on the scenario  execute the other option       or leave as default      N   echo  execute another option         esac  exit

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In response to others    You don t need to specify case in BASH4 just use the      to make a var lowercase  Also I strongly dislike putting code inside of the read block  get the result and deal with it outside of the read block IMO  Also include a  q  for quit IMO  Lastly why type  yes  just use -n1 and have the press y    Example   user can press y n and also q to just quit   ans    while true  do     read -p  So is MikeQ the greatest or what  y n q     -n1 ans     case   ans    in         y n q  break              echo  Answer y for yes   n for no  or q for quit         esac done  echo -e   nAnswer    ans   if       ans         q       then         echo  OK Quitting  we will assume that he is          exit 0 fi  if       ans         y       then         echo  MikeQ is the greatest    else         echo  No  MikeQ is not the greatest   fi

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echo  Please enter some input    read input variable echo  You entered   input variable

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In response to others    You don t need to specify case in BASH4 just use the      to make a var lowercase  Also I strongly dislike putting code inside of the read block  get the result and deal with it outside of the read block IMO  Also include a  q  for quit IMO  Lastly why type  yes  just use -n1 and have the press y    Example   user can press y n and also q to just quit   ans    while true  do     read -p  So is MikeQ the greatest or what  y n q     -n1 ans     case   ans    in         y n q  break              echo  Answer y for yes   n for no  or q for quit         esac done  echo -e   nAnswer    ans   if       ans         q       then         echo  OK Quitting  we will assume that he is          exit 0 fi  if       ans         y       then         echo  MikeQ is the greatest    else         echo  No  MikeQ is not the greatest   fi

User · Answer

yn       if     y      read -s -n 1 -p   y n     Y  echo  Y        then eval  1    else eval  2    fi   yn  echo yes   echo no  yn  echo absent no function works too

User · Answer

I suggest you use dialog     Linux Apprentice  Improve Bash Shell Scripts Using Dialog The dialog command enables the use of window boxes in shell scripts to make their use more interactive   it s simple and easy to use  there s also a gnome version called gdialog that takes the exact same parameters  but shows it GUI style on X

User · Answer

The simplest and most widely available method to get user input at a shell prompt is the read command  The best way to illustrate its use is a simple demonstration   while true  do     read -p  Do you wish to install this program   yn     case  yn in          Yy     make install  break            Nn     exit               echo  Please answer yes or no         esac done   Another method  pointed out by Steven Huwig  is Bash s select command  Here is the same example using select   echo  Do you wish to install this program   select yn in  Yes   No   do     case  yn in         Yes   make install  break           No   exit       esac done   With select you don t need to sanitize the input  ndash  it displays the available choices  and you type a number corresponding to your choice  It also loops automatically  so there s no need for a while true loop to retry if they give invalid input   Also  L  a Gris demonstrated a way to make the request language agnostic in her answer  Adapting my first example to better serve multiple languages might look like this   set --   locale LC MESSAGES  yesptrn   1   noptrn   2   yesword   3   noword   4   while true  do     read -p  Install    yesword      noword      yn     case  yn in           yesptrn       make install  break             noptrn       exit               echo  Answer   yesword      noword          esac done   Obviously other communication strings remain untranslated here  Install  Answer  which would need to be addressed in a more fully completed translation  but even a partial translation would be helpful in many cases   Finally  please check out the excellent answer by F  Hauri

User · Answer

One simple way to do this is with xargs -p or gnu parallel --interactive   I like the behavior of xargs a little better for this because it executes each command immediately after the prompt like other interactive unix commands  rather than collecting the yesses to run at the end    You can Ctrl-C after you get through the ones you wanted    e g     echo   xml   xargs -p -n 1 -J    mv    backup

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read -e -p  Enter your choice    choice   The -e option enables the user to edit the input using arrow keys   If you want to use a suggestion as input   read -e -i  yes  -p  Enter your choice    choice   -i option prints a suggestive input

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Single keypress only  Here s a longer  but reusable and modular approach    Returns 0 yes and 1 no No pressing enter required - just a single character Can press enter to accept the default choice Can disable default choice to force a selection Works for both zsh and bash    Defaulting to  no  when pressing enter  Note that the N is capitalsed  Here enter is pressed  accepting the default      confirm  Show dangerous command   amp  amp  echo  rm    Show dangerous command  y N     Also note  that  y N   was automatically appended  The default  no  is accepted  so nothing is echoed   Re-prompt until a valid response is given     confirm  Show dangerous command   amp  amp  echo  rm    Show dangerous command  y N   X Show dangerous command  y N   y rm     Defaulting to  yes  when pressing enter  Note that the Y is capitalised     confirm yes  Show dangerous command   amp  amp  echo  rm    Show dangerous command  Y n   rm     Above  I just pressed enter  so the command ran   No default on enter - require y or n    get yes keypress  Here you cannot press enter  Do you like this  y n     Here you cannot press enter  Do you like this  y n   k Here you cannot press enter  Do you like this  y n   Here you cannot press enter  Do you like this  y n   n   echo    1   Here  1 or false was returned  Note that with this lower-level function you ll need to provide your own  y n   prompt   Code    Read a single char from  dev tty  prompting with        Note  pressing enter will return a null string  Perhaps a version terminated with X and then remove it in caller    See https   unix stackexchange com a 367880 143394 for dealing with multi-byte  etc  function get keypress     local REPLY IFS     gt  dev tty printf   s             ZSH VERSION     amp  amp  read -rk1    Use -u0 to read from STDIN     See https   unix stackexchange com q 383197 143394 regarding   n  - gt           BASH VERSION     amp  amp   lt  dev tty read -rn1   printf   s    REPLY       Get a y n from the user  return yes 0  no 1 enter  2   Prompt using  1    If set  return  2 on pressing enter  useful for cancel or defualting function get yes keypress     local prompt    1 -Are you sure  y n        local enter return  2   local REPLY           prompt     amp  amp  prompt   y n       while REPLY   get keypress   prompt    do         REPLY     amp  amp  printf   n     REPLY blank if user presses enter     case   REPLY  in       Y y   return 0         N n   return 1                   enter return     amp  amp  return   enter return      esac   done      Credit  http   unix stackexchange com a 14444 143394   Prompt to confirm  defaulting to NO on  lt enter gt    Usage  confirm  Dangerous  Are you sure    amp  amp  rm   function confirm     local prompt      -Are you sure   y N       get yes keypress   prompt  1          Prompt to confirm  defaulting to YES on  lt enter gt  function confirm yes     local prompt      -Are you sure   Y n       get yes keypress   prompt  0

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The easiest way to achieve this with the least number of lines is as follows   read -p   lt Your Friendly Message here gt    y n cancel  CONDITION   if     CONDITION      y     then      do something here  fi   The if is just an example  it is up to you how to handle this variable

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I ve used the case statement a couple of times in such a scenario  using the case statment is a good way to go about it  A while loop  that ecapsulates the case block  that utilizes a boolean condition can be implemented in order to hold even more control of the program  and fulfill many other requirements  After the all the conditions have been met  a break can be used which will pass control back to the main part of the program  Also  to meet other conditions  of course conditional statements can be added to accompany the control structures  case statement and possible while loop   Example of using a case statement to fulfill your request      bin sh     For potential users of BSD  or other systems who do not   have a bash binary located in  bin the script will be directed to   a bourne-shell  e g   bin sh    NOTE  It would seem best for handling user entry errors or   exceptions  to put the decision required by the input    of the prompt in a case statement  case control structure     echo Would you like us to perform the option    Y N    read inPut  case  inPut in       echoing a command encapsulated by        backticks      executes the command      Y   echo  Do something crazy               depending on the scenario  execute the other option       or leave as default      N   echo  execute another option         esac  exit

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This solution reads a single character and calls a function on a yes response   read -p  Are you sure   y n    -n 1 echo if     REPLY      Yy       then     do something       fi

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Bash has select for this purpose   select result in Yes No Cancel do     echo  result done

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inquire         echo  -n   1  y n       read answer   finish  -1    while     finish     -1      do     finish  1      if     answer              then       answer        else       case  answer in         y   Y   yes   YES   answer  y            n   N   no   NO   answer  n               finish  -1              echo -n  Invalid response -- please reenter               read answer          esac     fi   done        other stuff  inquire  Install now

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I noticed that no one posted an answer showing multi-line echo menu for such simple user input so here is my go at it      bin bash  function ask user          echo -e                    1   Yes        2   No         3   Quit                    n   read -e -p  Select 1    choice  if     choice      1     then      do something  elif     choice      2     then      do something else  elif     choice      3     then      clear  amp  amp  exit 0  else      echo  Please select 1  2  or 3    amp  amp  sleep 3     clear  amp  amp  ask user  fi    ask user   This method was posted in the hopes that someone may find it useful and time-saving

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You can use the default REPLY on a read  convert to lowercase and compare to a set of variables with an expression  The script also supports ja si oui  read -rp  Do you want a demo   y n c          REPLY         c cancel       amp  amp    echo  Selected Cancel   exit 1     if      REPLY         y yes j ja s si o oui       then    echo  Positive  fi

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inquire         echo  -n   1  y n       read answer   finish  -1    while     finish     -1      do     finish  1      if     answer              then       answer        else       case  answer in         y   Y   yes   YES   answer  y            n   N   no   NO   answer  n               finish  -1              echo -n  Invalid response -- please reenter               read answer          esac     fi   done        other stuff  inquire  Install now

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read -e -p  Enter your choice    choice   The -e option enables the user to edit the input using arrow keys   If you want to use a suggestion as input   read -e -i  yes  -p  Enter your choice    choice   -i option prints a suggestive input

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You can use the default REPLY on a read  convert to lowercase and compare to a set of variables with an expression  The script also supports ja si oui  read -rp  Do you want a demo   y n c          REPLY         c cancel       amp  amp    echo  Selected Cancel   exit 1     if      REPLY         y yes j ja s si o oui       then    echo  Positive  fi

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Inspired by the answers of  Mark and  Myrddin I created this function for a universal prompt  uniprompt        while true  do         echo -e   1 c          read opt         array   2          case    array      in     opt    eval   3  opt  return 0   esac         echo -e   opt is not a correct value n      done     use it like this   unipromtp  Select an option   a -Do one  x - gt Do two  f - gt Do three      a x f  selection echo   selection

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I suggest you use dialog     Linux Apprentice  Improve Bash Shell Scripts Using Dialog The dialog command enables the use of window boxes in shell scripts to make their use more interactive   it s simple and easy to use  there s also a gnome version called gdialog that takes the exact same parameters  but shows it GUI style on X

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It is possible to handle a locale-aware  Yes   No choice  in a POSIX shell  by using the entries of the LC MESSAGES locale category  witch provides ready-made RegEx patterns to match an input  and strings for localized Yes No      usr bin env sh    Getting LC MESSAGES values into variables   shellcheck disable SC2046   Intended IFS splitting IFS     set --   locale LC MESSAGES   yesexpr   1  noexpr   2  yesstr   3  nostr   4  messages codeset   5    unused here  but kept as documentation    Display Yes   No   prompt into locale echo   yesstr    nostr       Read answer read -r yn    Test answer case   yn  in   match only work with the character class from the expression     yesexpr      echo  answer  yesstr         noexpr      echo  answer  nostr     esac   EDIT  As  Urhixidur mentioned in his comment      Unfortunately  POSIX only specifies the first two  yesexpr and noexpr   On Ubuntu 16  yesstr and nostr are empty    See  https   www ee ryerson ca  courses ele709 susv4 xrat V4 xbd chap07 html tag 21 07 03 06     LC MESSAGES      The yesstr and nostr locale keywords and the YESSTR and NOSTR langinfo items were formerly used to match user affirmative and negative responses  In POSIX 1-2008  the yesexpr  noexpr  YESEXPR  and NOEXPR extended regular expressions have replaced them  Applications should use the general locale-based messaging facilities to issue prompting messages which include sample desired responses    Alternatively using locales the Bash way      usr bin env bash  IFS    n  read -r -d    yesexpr noexpr    lt   lt  locale LC MESSAGES   printf -v yes or no regex    s    s     yesexpr    noexpr   printf -v prompt   Please answer Yes   s  or No   s       yesexpr    noexpr   declare -- answer    until      answer      yes or no regex     do   read -rp   prompt  answer done  if    -n    BASH REMATCH 1        then   echo   You answered  Yes  else   echo   No  was your answer   fi   The answer is matched using locale environment s provided regexps   To translate the remaining messages  use bash --dump-po-strings scriptname to output the po strings for localization      scriptname 8 msgid  Please answer Yes   s  or No   s     msgstr       scriptname 17 msgid  You answered  Yes  msgstr       scriptname 19 msgid  No  was your answer   msgstr

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inquire         echo  -n   1  y n       read answer   finish  -1    while     finish     -1      do     finish  1      if     answer              then       answer        else       case  answer in         y   Y   yes   YES   answer  y            n   N   no   NO   answer  n               finish  -1              echo -n  Invalid response -- please reenter               read answer          esac     fi   done        other stuff  inquire  Install now

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At least five answers for one generic question   Depending on   posix compliant  could work on poor systems with generic shell environments bash specific  using so called bashisms   and if you want   simple   in line   question   answer  generic solutions  pretty formatted interfaces  like ncurses or more graphical using libgtk or libqt    use powerful readline history capability   1  POSIX generic solutions  You could use the read command  followed by if     then     else   echo -n  Is this a good question  y n     read answer       if echo   answer    grep -iq   y   then     if     answer        answer  Yy       then     echo Yes else     echo No fi    Thanks to Adam Katz s comment  Replaced the test above with one that is more portable and avoids one fork    POSIX  but single key feature  But if you don t want the user to have to hit Return  you could write    Edited  As  JonathanLeffler rightly suggest  saving stty s configuration could be better than simply force them to sane    echo -n  Is this a good question  y n     old stty cfg   stty -g  stty raw -echo   answer   head -c 1    stty  old stty cfg   Careful playing with stty if echo   answer    grep -iq   y   then     echo Yes else     echo No fi   Note  This was tested under sh  bash  ksh  dash and busybox   Same  but waiting explicitly for y or n     bin sh echo -n  Is this a good question  y n     old stty cfg   stty -g  stty raw -echo answer    while   head -c 1   grep -i   ny    do true  done   stty  old stty cfg if echo   answer    grep -iq   y   then     echo Yes else     echo No fi   Using dedicated tools  There are many tools which were built using libncurses  libgtk  libqt or other graphical libraries  For example  using whiptail   if whiptail --yesno  Is this a good question  20 60  then     echo Yes else     echo No fi   Depending on your system  you may need to replace whiptail with another similiar tool   dialog --yesno  Is this a good question  20 60  amp  amp  echo Yes  gdialog --yesno  Is this a good question  20 60  amp  amp  echo Yes  kdialog --yesno  Is this a good question  20 60  amp  amp  echo Yes   where 20 is height of dialog box in number of lines and 60 is width of  the dialog box  These tools all have near same syntax   DIALOG whiptail if   -x  usr bin gdialog    then DIALOG gdialog   fi if   -x  usr bin xdialog    then DIALOG xdialog   fi      DIALOG --yesno       2  Bash specific solutions  Basic in line method  read -p  Is this a good question  y n     answer case   answer 0 1  in     y Y           echo Yes                        echo No        esac   I prefer to use case so I could even test for yes   ja   si   oui if needed     in line with single key feature  Under bash  we can specify the length of intended input for for the read command   read -n 1 -p  Is this a good question  y n     answer   Under bash  read command accepts a timeout parameter  which could be useful   read -t 3 -n 1 -p  Is this a good question  y n     answer   -z   answer     amp  amp  answer  Yes     if  yes  have to be default choice   3   Some tricks for dedicated tools  More sophisticated dialog boxes  beyond simple yes - no purposes   dialog --menu  Is this a good question  20 60 12 y Yes n No m Maybe   Progress bar   dialog --gauge  Filling the tank  20 60 0  lt   lt       for i in  1  100  do         printf  XXX n d n   a  b  T T progress   d nXXX n   i -1  i         sleep  033     done      Little demo      bin sh while true  do       -x    which   DIALOG             DIALOG dialog     DIALOG    DIALOG --menu  Which tool for next run   20 60 12 2 gt  amp 1               whiptail        dialog boxes from shell scripts   gt  dev tty               dialog          dialog boxes from shell with ncurses                gdialog         dialog boxes from shell with Gtk                kdialog         dialog boxes from shell with Kde       exit     clear echo  Choosed   DIALOG       for i in  seq 1 100  do         date    printf  XXX n d n  a   b   T progress   d nXXX n   i  i           sleep  0125       done    DIALOG --gauge  Filling the tank  20 60 0      DIALOG --infobox  This is a simple info box n nNo action required  20 60     sleep 3     if  DIALOG --yesno   Do you like this demo   20 60  then         AnsYesNo Yes  else AnsYesNo No  fi     AnsInput    DIALOG --inputbox  A text   20 60  Text here     2 gt  amp 1  gt  dev tty      AnsPass    DIALOG --passwordbox  A secret   20 60  First     2 gt  amp 1  gt  dev tty       DIALOG --textbox  etc motd 20 60     AnsCkLst    DIALOG --checklist  Check some     20 60 12           Correct  This demo is useful         off           Fun         This demo is nice         off           Strong         This demo is complex         on 2 gt  amp 1  gt  dev tty      AnsRadio    DIALOG --radiolist  I will   20 60 12             -1   Downgrade this answer         off              0   Not do anything                 on              1   Upgrade this anser         off 2 gt  amp 1  gt  dev tty      out  Your answers  nLike   AnsYesNo nInput   AnsInput nSecret   AnsPass       DIALOG --msgbox   out nAttribs   AnsCkLst nNote   AnsRadio  20 60   done   More sample  Have a look at Using whiptail for choosing USB device and USB removable storage selector  USBKeyChooser  5  Using readline s history  Example      bin bash  set -i HISTFILE    myscript history history -c history -r  myread         read -e -p   gt     1     history -s    1    trap  history -a exit  0 1 2 3 6  while myread line do     case   line      in         exit    break                    echo  Doing something with   line            esac   done   This will create a file  myscript history in your  HOME directory  than you could use readline s history commands  like Up   Down  Ctrl r and others

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It is possible to handle a locale-aware  Yes   No choice  in a POSIX shell  by using the entries of the LC MESSAGES locale category  witch provides ready-made RegEx patterns to match an input  and strings for localized Yes No      usr bin env sh    Getting LC MESSAGES values into variables   shellcheck disable SC2046   Intended IFS splitting IFS     set --   locale LC MESSAGES   yesexpr   1  noexpr   2  yesstr   3  nostr   4  messages codeset   5    unused here  but kept as documentation    Display Yes   No   prompt into locale echo   yesstr    nostr       Read answer read -r yn    Test answer case   yn  in   match only work with the character class from the expression     yesexpr      echo  answer  yesstr         noexpr      echo  answer  nostr     esac   EDIT  As  Urhixidur mentioned in his comment      Unfortunately  POSIX only specifies the first two  yesexpr and noexpr   On Ubuntu 16  yesstr and nostr are empty    See  https   www ee ryerson ca  courses ele709 susv4 xrat V4 xbd chap07 html tag 21 07 03 06     LC MESSAGES      The yesstr and nostr locale keywords and the YESSTR and NOSTR langinfo items were formerly used to match user affirmative and negative responses  In POSIX 1-2008  the yesexpr  noexpr  YESEXPR  and NOEXPR extended regular expressions have replaced them  Applications should use the general locale-based messaging facilities to issue prompting messages which include sample desired responses    Alternatively using locales the Bash way      usr bin env bash  IFS    n  read -r -d    yesexpr noexpr    lt   lt  locale LC MESSAGES   printf -v yes or no regex    s    s     yesexpr    noexpr   printf -v prompt   Please answer Yes   s  or No   s       yesexpr    noexpr   declare -- answer    until      answer      yes or no regex     do   read -rp   prompt  answer done  if    -n    BASH REMATCH 1        then   echo   You answered  Yes  else   echo   No  was your answer   fi   The answer is matched using locale environment s provided regexps   To translate the remaining messages  use bash --dump-po-strings scriptname to output the po strings for localization      scriptname 8 msgid  Please answer Yes   s  or No   s     msgstr       scriptname 17 msgid  You answered  Yes  msgstr       scriptname 19 msgid  No  was your answer   msgstr

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Use the read command   echo Would you like to install    Y or N    read x    now check if  x is  y  if     x     y     then       do something here  fi   and then all of the other stuff you need

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To get a nice ncurses-like inputbox use the command dialog like this      bin bash if  dialog --title  Message  --yesno  Want to do something risky   6 25    message box will have the size 25x6 characters then      echo  Let s do something risky        do something risky else      echo  Let s stay boring  fi   The dialog package is installed by default at least with SUSE Linux  Looks like

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You want    Bash builtin commands  i e  portable  Check TTY Default answer Timeout Colored question   Snippet  do xxxx y                        In batch mode   gt  Default is Yes    -t 0     amp  amp                     If TTY   gt  Prompt the question read -n 1 -p    e 1 32m Do xxxx   Y n  e 0m   do xxxx    Store the answer in  do xxxx if     do xxxx      y Y          Do if  y  or  Y  or empty then     xxxx fi   Explanations      -t 0     amp  amp  read        Call command read if TTY read -n 1    Wait for one character    e 1 32m      e 0m      Print in green  green is fine because readable on both white black backgrounds      do xxxx      y Y          bash regex   Timeout    Default answer is No  do xxxx y    -t 0     amp  amp                        Timeout 5 seconds  read -t 5  read -t 5 -n 1 -p    e 1 32m Do xxxx   Y n  e 0m   do xxxx       read  fails  on timeout do xxxx n                           Timeout   gt  answer No if     do xxxx      y Y       then     xxxx fi

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Bash has select for this purpose   select result in Yes No Cancel do     echo  result done

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read -p  Are you alright   y n    RESP if     RESP     y     then   echo  Glad to hear it  else   echo  You need more bash programming  fi

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Here s something I put together      bin sh  promptyn          while true  do         read -p   1   yn         case  yn in              Yy     return 0                Nn     return 1                   echo  Please answer yes or no             esac     done    if promptyn  is the sky blue    then     echo  yes  else     echo  no  fi   I m a beginner  so take this with a grain of salt  but it seems to work

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In my case I needed to read from a downloaded script i e  curl -Ss https   example com installer sh   sh The line read yesno  lt   dev tty made it echo -n  quot These files will be uploaded  Is this ok   y n   quot  read yesno  lt   dev tty  if    quot x yesno quot     quot xy quot    then          Yes else       No fi

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more generic would be   function menu        title  Question time      prompt  Select       options   Yes   No   Maybe       echo   title      PS3   prompt      select opt in    options       Quit Cancel   do         case   REPLY  in             1   echo  You picked  opt which is option  REPLY                2   echo  You picked  opt which is option  REPLY                3   echo  You picked  opt which is option  REPLY                       options     1      clear  echo  Goodbye    exit                  echo  Invalid option  Try another one   continue            esac      done      return

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You want    Bash builtin commands  i e  portable  Check TTY Default answer Timeout Colored question   Snippet  do xxxx y                        In batch mode   gt  Default is Yes    -t 0     amp  amp                     If TTY   gt  Prompt the question read -n 1 -p    e 1 32m Do xxxx   Y n  e 0m   do xxxx    Store the answer in  do xxxx if     do xxxx      y Y          Do if  y  or  Y  or empty then     xxxx fi   Explanations      -t 0     amp  amp  read        Call command read if TTY read -n 1    Wait for one character    e 1 32m      e 0m      Print in green  green is fine because readable on both white black backgrounds      do xxxx      y Y          bash regex   Timeout    Default answer is No  do xxxx y    -t 0     amp  amp                        Timeout 5 seconds  read -t 5  read -t 5 -n 1 -p    e 1 32m Do xxxx   Y n  e 0m   do xxxx       read  fails  on timeout do xxxx n                           Timeout   gt  answer No if     do xxxx      y Y       then     xxxx fi

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Most of the times in such scenarios  you need to continue executing the script till the user keeps on entering  yes  and only need to stop when user enters  no   The below snippet would help you achieve this      bin bash input  yes  while     input      yes    do   echo  execute script functionality here        echo  Do you want to continue  yes no      read input done

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read -p  Are you alright   y n    RESP if     RESP     y     then   echo  Glad to hear it  else   echo  You need more bash programming  fi

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I suggest you use dialog     Linux Apprentice  Improve Bash Shell Scripts Using Dialog The dialog command enables the use of window boxes in shell scripts to make their use more interactive   it s simple and easy to use  there s also a gnome version called gdialog that takes the exact same parameters  but shows it GUI style on X

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more generic would be   function menu        title  Question time      prompt  Select       options   Yes   No   Maybe       echo   title      PS3   prompt      select opt in    options       Quit Cancel   do         case   REPLY  in             1   echo  You picked  opt which is option  REPLY                2   echo  You picked  opt which is option  REPLY                3   echo  You picked  opt which is option  REPLY                       options     1      clear  echo  Goodbye    exit                  echo  Invalid option  Try another one   continue            esac      done      return

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In my case I needed to read from a downloaded script i e  curl -Ss https   example com installer sh   sh The line read yesno  lt   dev tty made it echo -n  quot These files will be uploaded  Is this ok   y n   quot  read yesno  lt   dev tty  if    quot x yesno quot     quot xy quot    then          Yes else       No fi

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As a friend of a one line command I used the following   while   -z  prompt    do read -p  Continue  y n    choice case   choice  in y Y   prompt true  break   n N   exit 0   esac  done  prompt     Written longform  it works like this   while   -z  prompt      do read -p  Continue  y n    choice    case   choice  in     y Y   prompt true  break       n N   exit 0     esac  done  prompt

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The absolute most simple solution is this one-liner without clever tricks  read -p  quot press enter     quot  y  It reminds of the classic DOS Hit any key to continue  except that it waits for the Enter key  not just any key  True  this does not offer you three options for Yes No Cancel  but it is useful where you accept control-C as No resp  Cancel in simple scripts like  e g      bin sh echo Backup this project read -p  quot press enter     quot  y rsync -tavz    media hard to remember path backup projects yourproject   because you don t like to need to remember ugly commands and paths  but neither scripts that run too fast  without giving you a chance to stop before you decide it is not the script you intended to run

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echo  Please enter some input    read input variable echo  You entered   input variable

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Bash has select for this purpose   select result in Yes No Cancel do     echo  result done

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The absolute most simple solution is this one-liner without clever tricks  read -p  quot press enter     quot  y  It reminds of the classic DOS Hit any key to continue  except that it waits for the Enter key  not just any key  True  this does not offer you three options for Yes No Cancel  but it is useful where you accept control-C as No resp  Cancel in simple scripts like  e g      bin sh echo Backup this project read -p  quot press enter     quot  y rsync -tavz    media hard to remember path backup projects yourproject   because you don t like to need to remember ugly commands and paths  but neither scripts that run too fast  without giving you a chance to stop before you decide it is not the script you intended to run

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inquire         echo  -n   1  y n       read answer   finish  -1    while     finish     -1      do     finish  1      if     answer              then       answer        else       case  answer in         y   Y   yes   YES   answer  y            n   N   no   NO   answer  n               finish  -1              echo -n  Invalid response -- please reenter               read answer          esac     fi   done        other stuff  inquire  Install now

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One simple way to do this is with xargs -p or gnu parallel --interactive   I like the behavior of xargs a little better for this because it executes each command immediately after the prompt like other interactive unix commands  rather than collecting the yesses to run at the end    You can Ctrl-C after you get through the ones you wanted    e g     echo   xml   xargs -p -n 1 -J    mv    backup

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Single keypress only  Here s a longer  but reusable and modular approach    Returns 0 yes and 1 no No pressing enter required - just a single character Can press enter to accept the default choice Can disable default choice to force a selection Works for both zsh and bash    Defaulting to  no  when pressing enter  Note that the N is capitalsed  Here enter is pressed  accepting the default      confirm  Show dangerous command   amp  amp  echo  rm    Show dangerous command  y N     Also note  that  y N   was automatically appended  The default  no  is accepted  so nothing is echoed   Re-prompt until a valid response is given     confirm  Show dangerous command   amp  amp  echo  rm    Show dangerous command  y N   X Show dangerous command  y N   y rm     Defaulting to  yes  when pressing enter  Note that the Y is capitalised     confirm yes  Show dangerous command   amp  amp  echo  rm    Show dangerous command  Y n   rm     Above  I just pressed enter  so the command ran   No default on enter - require y or n    get yes keypress  Here you cannot press enter  Do you like this  y n     Here you cannot press enter  Do you like this  y n   k Here you cannot press enter  Do you like this  y n   Here you cannot press enter  Do you like this  y n   n   echo    1   Here  1 or false was returned  Note that with this lower-level function you ll need to provide your own  y n   prompt   Code    Read a single char from  dev tty  prompting with        Note  pressing enter will return a null string  Perhaps a version terminated with X and then remove it in caller    See https   unix stackexchange com a 367880 143394 for dealing with multi-byte  etc  function get keypress     local REPLY IFS     gt  dev tty printf   s             ZSH VERSION     amp  amp  read -rk1    Use -u0 to read from STDIN     See https   unix stackexchange com q 383197 143394 regarding   n  - gt           BASH VERSION     amp  amp   lt  dev tty read -rn1   printf   s    REPLY       Get a y n from the user  return yes 0  no 1 enter  2   Prompt using  1    If set  return  2 on pressing enter  useful for cancel or defualting function get yes keypress     local prompt    1 -Are you sure  y n        local enter return  2   local REPLY           prompt     amp  amp  prompt   y n       while REPLY   get keypress   prompt    do         REPLY     amp  amp  printf   n     REPLY blank if user presses enter     case   REPLY  in       Y y   return 0         N n   return 1                   enter return     amp  amp  return   enter return      esac   done      Credit  http   unix stackexchange com a 14444 143394   Prompt to confirm  defaulting to NO on  lt enter gt    Usage  confirm  Dangerous  Are you sure    amp  amp  rm   function confirm     local prompt      -Are you sure   y N       get yes keypress   prompt  1          Prompt to confirm  defaulting to YES on  lt enter gt  function confirm yes     local prompt      -Are you sure   Y n       get yes keypress   prompt  0

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The easiest way to achieve this with the least number of lines is as follows   read -p   lt Your Friendly Message here gt    y n cancel  CONDITION   if     CONDITION      y     then      do something here  fi   The if is just an example  it is up to you how to handle this variable

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You can use the built-in read command   Use the -p option to prompt the user with a question   Since BASH4  you can now use -i to suggest an answer    read -e -p  Enter the path to the file    -i   usr local etc   FILEPATH echo  FILEPATH    But remember to use the  readline  option -e to allow line editing with arrow keys   If you want a  yes   no  logic  you can do something like this   read -e -p   List the content of your home dir    Y n    YN      YN     y      YN     Y      YN           amp  amp  ls -la

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This is what I usually need in a script function    default answer is Yes  if you hit ENTER accept also z  in case you mix up you are on QWERTZ Layout  accept other lanyuages   ja    Oui        handle the right exit in case you are inside a function   while true  do     read -p  Continue  Y n     -n 1 -r -e yn     case    yn -Y   in          YyZzOoJj     echo  break             Nn          0      BASH SOURCE      amp  amp  exit 1    return 1      handle exits from shell or function but don t exit interactive shell             echo  Please answer yes or no         esac done echo  and off we go

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Multiple choice version   ask                                1 question  2 options       set REPLY       options  x    y        while   true   do         printf   s   s      1    2          stty cbreak         REPLY   dd if  dev tty bs 1 count 1 2 gt   dev null          stty -cbreak         test   REPLY        printf   n     amp  amp  printf   n                        IFS                 for o in  2  do                 if     REPLY       o          then                     printf   n                      break                 fi             done             grep    gt   dev null  amp  amp  return     done     Example     ask  continue    y yes n no m maybe  continue   y yes n no m maybe  g continue   y yes n no m maybe  k continue   y yes n no m maybe  y     It will set REPLY to y  inside the script

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The simplest and most widely available method to get user input at a shell prompt is the read command  The best way to illustrate its use is a simple demonstration   while true  do     read -p  Do you wish to install this program   yn     case  yn in          Yy     make install  break            Nn     exit               echo  Please answer yes or no         esac done   Another method  pointed out by Steven Huwig  is Bash s select command  Here is the same example using select   echo  Do you wish to install this program   select yn in  Yes   No   do     case  yn in         Yes   make install  break           No   exit       esac done   With select you don t need to sanitize the input  ndash  it displays the available choices  and you type a number corresponding to your choice  It also loops automatically  so there s no need for a while true loop to retry if they give invalid input   Also  L  a Gris demonstrated a way to make the request language agnostic in her answer  Adapting my first example to better serve multiple languages might look like this   set --   locale LC MESSAGES  yesptrn   1   noptrn   2   yesword   3   noword   4   while true  do     read -p  Install    yesword      noword      yn     case  yn in           yesptrn       make install  break             noptrn       exit               echo  Answer   yesword      noword          esac done   Obviously other communication strings remain untranslated here  Install  Answer  which would need to be addressed in a more fully completed translation  but even a partial translation would be helpful in many cases   Finally  please check out the excellent answer by F  Hauri

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You can use the built-in read command   Use the -p option to prompt the user with a question   Since BASH4  you can now use -i to suggest an answer    read -e -p  Enter the path to the file    -i   usr local etc   FILEPATH echo  FILEPATH    But remember to use the  readline  option -e to allow line editing with arrow keys   If you want a  yes   no  logic  you can do something like this   read -e -p   List the content of your home dir    Y n    YN      YN     y      YN     Y      YN           amp  amp  ls -la

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Yes   No   Cancel  Function     usr bin env bash  confirm       local message        local result       echo -n   gt   message  Yes No Cancel     gt  amp 2    while   -z   result      do     read -s -n 1 choice     case   choice  in       y Y   result  Y           n N   result  N           c C   result  C         esac   done    echo  result     Usage  case    confirm  Confirm    in   Y   echo  Yes       N   echo  No       C   echo  Cancel     esac   Confirm with clean user input  Function     usr bin env bash  confirm       local message        local result 3    echo -n   gt   message  y n     gt  amp 2    while     result -gt 1      do     read -s -n 1 choice     case   choice  in       y Y   result 0          n N   result 1        esac   done    return  result     Usage  if  confirm  Confirm     then   echo  Yes  else   echo  No  fi

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echo  Please enter some input    read input variable echo  You entered   input variable

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Bash has select for this purpose   select result in Yes No Cancel do     echo  result done

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I suggest you use dialog     Linux Apprentice  Improve Bash Shell Scripts Using Dialog The dialog command enables the use of window boxes in shell scripts to make their use more interactive   it s simple and easy to use  there s also a gnome version called gdialog that takes the exact same parameters  but shows it GUI style on X

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Yes   No   Cancel  Function     usr bin env bash  confirm       local message        local result       echo -n   gt   message  Yes No Cancel     gt  amp 2    while   -z   result      do     read -s -n 1 choice     case   choice  in       y Y   result  Y           n N   result  N           c C   result  C         esac   done    echo  result     Usage  case    confirm  Confirm    in   Y   echo  Yes       N   echo  No       C   echo  Cancel     esac   Confirm with clean user input  Function     usr bin env bash  confirm       local message        local result 3    echo -n   gt   message  y n     gt  amp 2    while     result -gt 1      do     read -s -n 1 choice     case   choice  in       y Y   result 0          n N   result 1        esac   done    return  result     Usage  if  confirm  Confirm     then   echo  Yes  else   echo  No  fi

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This is what I usually need in a script function    default answer is Yes  if you hit ENTER accept also z  in case you mix up you are on QWERTZ Layout  accept other lanyuages   ja    Oui        handle the right exit in case you are inside a function   while true  do     read -p  Continue  Y n     -n 1 -r -e yn     case    yn -Y   in          YyZzOoJj     echo  break             Nn          0      BASH SOURCE      amp  amp  exit 1    return 1      handle exits from shell or function but don t exit interactive shell             echo  Please answer yes or no         esac done echo  and off we go

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As a friend of a one line command I used the following   while   -z  prompt    do read -p  Continue  y n    choice case   choice  in y Y   prompt true  break   n N   exit 0   esac  done  prompt     Written longform  it works like this   while   -z  prompt      do read -p  Continue  y n    choice    case   choice  in     y Y   prompt true  break       n N   exit 0     esac  done  prompt

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Most of the times in such scenarios  you need to continue executing the script till the user keeps on entering  yes  and only need to stop when user enters  no   The below snippet would help you achieve this      bin bash input  yes  while     input      yes    do   echo  execute script functionality here        echo  Do you want to continue  yes no      read input done

[linux] How do I prompt for Yes/No/Cancel input in a Linux shell script?

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