Is there a TRY CATCH command in Bash

Question

I'm writing a shell script and need to check that a terminal app has been installed. I want to use a TRY/CATCH command to do this unless there is a neater way.

Answer 1

Based on some answers I found here, I made myself a small helper file to source for my projects:

trycatch.sh

#!/bin/bash  function try() {     [[ $- = *e* ]]; SAVED_OPT_E=$?     set +e }  function throw() {     exit $1 }  function catch() {     export ex_code=$?     (( $SAVED_OPT_E )) && set +e     return $ex_code }  function throwErrors() {     set -e }  function ignoreErrors() {     set +e } 

here is an example how it looks in use:

#!/bin/bash export AnException=100 export AnotherException=101  # start with a try try (   # open a subshell !!!     echo "do something"     [ someErrorCondition ] && throw $AnException      echo "do something more"     executeCommandThatMightFail || throw $AnotherException      throwErrors # automaticatly end the try block, if command-result is non-null     echo "now on to something completely different"     executeCommandThatMightFail      echo "it's a wonder we came so far"     executeCommandThatFailsForSure || true # ignore a single failing command      ignoreErrors # ignore failures of commands until further notice     executeCommand1ThatFailsForSure     local result = $(executeCommand2ThatFailsForSure)     [ result != "expected error" ] && throw $AnException # ok, if it's not an expected error, we want to bail out!     executeCommand3ThatFailsForSure      # make sure to clear $ex_code, otherwise catch * will run     # echo "finished" does the trick for this example     echo "finished" ) # directly after closing the subshell you need to connect a group to the catch using || catch || {     # now you can handle     case $ex_code in         $AnException)             echo "AnException was thrown"         ;;         $AnotherException)             echo "AnotherException was thrown"         ;;         *)             echo "An unexpected exception was thrown"             throw $ex_code # you can rethrow the "exception" causing the script to exit if not caught         ;;     esac } 

Answer 2

Is there a TRY CATCH command in Bash?

No.

Bash doesn't have as many luxuries as one can find in many programming languages.

There is no try/catch in bash; however, one can achieve similar behavior using && or ||.

Using ||:

if command1 fails then command2 runs as follows

command1 || command2 

Similarly, using &&, command2 will run if command1 is successful

The closest approximation of try/catch is as follows

{ # try      command1 &&     #save your output  } || { # catch     # save log for exception  } 

Also bash contains some error handling mechanisms, as well

set -e 

it stops your script if any simple command fails.

And also why not if...else. It is your best friend.