Exception handling in shell scripting?

{
    # command which may fail and give an error 
} || {
   # command which should be run instead of the above failing      command
}

The if/else structure and exit codes can help you fake some of it. This should work in Bash or Bourne (sh).

if foo ; then
else
  e=$?        # return code from if
  if [ "${e}" -eq "1"]; then
    echo "Foo returned exit code 1"
  elif [ "${e}" -gt "1"]; then
    echo "Foo returned BAD exit code ${e}"
  fi
fi

There is not really a try/catch in bash (i assume you're using bash), but you can achieve a quite similar behaviour using && or ||.

In this example, you want to run fallback_command if a_command fails (returns a non-zero value):

a_command || fallback_command

And in this example, you want to execute second_command if a_command is successful (returns 0):

a_command && second_command

They can easily be mixed together by using a subshell, for example, the following command will execute a_command, if it succeeds it will then run other_command, but if a_command or other_command fails, fallback_command will be executed:

(a_command && other_command) || fallback_command