Is there a goto statement in bash

Question

Is there a  goto  statement in bash   I know It is considered bad practice  but I need specifically  goto

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This solution had the following issues    Indiscriminately removes all code lines ending in a   Treates label  anywhere on a line as a label   Here s a fixed  shell-check clean  version        bin bash    GOTO for bash  based upon https   stackoverflow com a 31269848 5353461 function goto    local label  1  cmd   sed -En       space        space     label    space        a n p ba      0    eval   cmd   exit    start   1 -start  goto   start     GOTO start  by default   start    Comments can occur after labels echo start goto end      skip     Whitespace is allowed echo this is usually skipped    end    echo end

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If you re testing debugging a bash script  and simply want to skip forwards past one or more sections of code  here is a very simple way to do it that is also very easy to find and remove later  unlike most of the methods described above       bin bash  echo  Run this   cat  gt  dev null  lt  lt GOTO 1  echo  Don t run this   GOTO 1  echo  Also run this   cat  gt  dev null  lt  lt GOTO 2  echo  Don t run this either   GOTO 2  echo  Yet more code I want to run    To put your script back to normal  just delete any lines with GOTO   We can also prettify this solution  by adding a goto command as an alias      bin bash  shopt -s expand aliases alias goto  cat  gt  dev null  lt  lt    goto GOTO 1  echo  Don t run this   GOTO 1  echo  Run this   goto GOTO 2  echo  Don t run this either   GOTO 2  echo  All done    Aliases don t usually work in bash scripts  so we need the shopt command to fix that   If you want to be able to enable disable your goto s  we need a little bit more      bin bash  shopt -s expand aliases if   -n   DEBUG      then   alias goto  cat  gt  dev null  lt  lt   else   alias goto     fi  goto   GOTO 1   echo  Don t run this    GOTO1  echo  Run this   goto   GOTO 2   echo  Don t run this either    GOTO 2  echo  All done    Then you can do export DEBUG TRUE before running the script   The labels are comments  so won t cause syntax errors if disable our goto s  by setting goto to the     no-op   but this means we need to quote them in our goto statements   Whenever using any kind of goto solution  you need to be careful that the code you re jumping past doesn t set any variables that you rely on later - you may need to move those definitions to the top of your script  or just above one of your goto statements

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This is a small correction of the Judy Schmidt script put up by Hubbbitus    Putting non-escaped labels in the script was problematic on the machine and caused it to crash  This was easy enough to resolve by adding   to escape the labels  Thanks to Alexej Magura and access granted for their suggestions      bin bash   include this boilerplate function goto     label  1 cmd   sed -n     label     a n p ba     0   grep -v       eval   cmd  exit    start   1 - start    goto  start   start  echo  start  goto bing   boom  echo boom goto eof   bang  echo bang goto boom   bing  echo bing goto bang   eof  echo  the end mother-hugger

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It indeed may be useful for some debug or demonstration needs   I found that Bob Copeland solution http   bobcopeland com blog 2012 10 goto-in-bash  elegant      bin bash   include this boilerplate function jumpto       label  1     cmd   sed -n    label    a n p ba     0   grep -v           eval   cmd      exit    start   1 - start    jumpto  start  start    your script goes here    x 100 jumpto foo  mid  x 101 echo  This is not printed    foo  x   x -10  echo x is  x   results in       test sh x is 100     test sh foo x is 10     test sh mid This is not printed  x is 101

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If you are using it to skip part of a large script for debugging  see Karl Nicoll s comment   then if false could be a good option  not sure if  false  is always available  for me it is in  bin false          Code I want to run here      if false  then        Code I want to skip here      fi        I want to resume here       The difficulty comes in when it s time to rip out your debugging code   The  if false  construct is pretty straightforward and memorable  but how do you find the matching fi   If your editor allows you to block indent  you could indent the skipped block  then you ll want to put it back when you re done    Or a comment on the fi line  but it would have to be something you ll remember  which I suspect will be very programmer-dependent

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There is no goto in bash   Here is some dirty workaround using trap which jumps only backwards       bin bash -e trap   echo I am sleep 1 echo here now    EXIT  echo foo goto trap 2 gt   dev null echo bar   Output       test sh  foo I am here now    This shouldn t be used in that way  but only for educational purposes   Here is why this works   trap is using exception handling to achieve the change in code flow   In this case the trap is catching anything that causes the script to EXIT   The command goto doesn t exist  and hence throws an error  which would ordinarily exit the script   This error is being caught with trap  and the 2 gt  dev null hides the error message that would ordinarily be displayed   This implementation of goto is obviously not reliable  since any non-existent command  or any other error  for that manner   would execute the same trap command   In particular  you cannot choose which label to go-to     Basically in real scenario you don t need any goto statements  they re redundant as random calls to different places only make your code difficult to understand   If your code is invoked many times  then consider to use loop and changing its workflow to use continue and break   If your code repeats it-self  consider writing the function and calling it as many times as you want   If your code needs to jump into specific section based on the variable value  then consider using case statement   If you can separate your long code into smaller pieces  consider moving it into separate files and call them from the parent script

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I found out a way to do this using functions   Say  for example  you have 3 choices  A  B  and C  A and Bexecute a command  but C gives you more info and takes you to the original prompt again  This can be done using functions   Note that since the line containg function demoFunction is just setting up the function  you need to call demoFunction after that script so the function will actually run    You can easily adapt this by writing multiple other functions and calling them if you need to  GOTO  another place in your shell script   function demoFunction           read -n1 -p  Pick a letter to run a command  A  B  or C for more info    runCommand          case  runCommand in             a A  printf   n tpwd being executed    n   amp  amp  pwd               b B  printf   n tls being executed    n   amp  amp  ls               c C  printf   n toption A runs pwd  option B runs ls n   amp  amp  demoFunction           esac    demoFunction

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A simple searchable goto for the use of commenting out code blocks when debugging    GOTO false if   GOTO   then     echo  GOTO failed          fi   End of GOTO echo  GOTO done    Result is-  GOTO done

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Although others have already clarified that there is no direct goto equivalent in bash  and provided the closest alternatives such as functions  loops  and break   I would like to illustrate how using a loop plus break can simulate a specific type of goto statement   The situation where I find this the most useful is when I need to return to the beginning of a section of code if certain conditions are not met  In the example below  the while loop will run forever until ping stops dropping packets to a test IP      bin bash  TestIP  8 8 8 8     Loop forever  until break is issued  while true  do        Do a simple test for Internet connectivity     PacketLoss   ping   TestIP  -c 2   grep -Eo   0-9    packet loss    grep -Eo    0-9           Exit the loop if ping is no longer dropping packets     if     PacketLoss     0    then         echo  Connection restored          break     else         echo  No connectivity      fi done

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You can use case in bash to simulate a goto      bin bash  case bar in   foo      echo foo       amp     bar      echo bar       amp            echo star        esac   produces   bar star

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There is one more ability to achieve a desired results  command trap  It can be used to clean-up purposes for example

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No  there is not  see  sect 3 2 4  Compound Commands  in the Bash Reference Manual for information about the control structures that do exist  In particular  note the mention of break and continue  which aren t as flexible as goto  but are more flexible in Bash than in some languages  and may help you achieve what you want   Whatever it is that you want

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