Exit script function in bash

Question

I have below script which I will be running via jenkins:

#!/bin/bash

function getToken
{ 
    echo "function to get token"
}

function call_init
{
    echo "Creating a config file"

}

function call_list
{
    echo "calling list*"
}

#Starting execution
if [[ -z "$TOKEN" ]]; then
    TOKEN=$(getToken)
    if [ $? -ne 0 ]; then
    exit 1
    fi
fi

echo "Creating a config file and populating it"
call_init
if [ $? -ne 0 ]; then
exit 1
fi


if [ -n $ACTION ]; then
case "$ACTION" in

'list')  echo "Action is list"
     call_list
     if [ $? -ne 0 ]; then
     exit 1
     fi   
;;
'update')  echo  "Section is update"
;;
'delete')  echo  "Section is delete"
;;
*) echo "This is a default message"
   ;;
esac
fi

As you see that theres a lot of repetition of the below code which helps me fail the jenkins job by throwing the error code 1:

if [ $? -ne 0 ]; then
exit 1
fi

What would be the most efficient way to handle this? I need it to always exit the code with 1.

P.S: I went through Checking Bash exit status of several commands efficiently, however was not able to get it work for the above script.

Answer 1

The best approach is to use explicit error checking.

Your current pattern can be streamlined, the following are all equivelant:

run_command
if [ $? -ne 0 ]; then
    print_error
    exit 1
fi

if ! run_command; then
    print_error
    exit 1
fi

run_command || { print_error; exit 1; }

Or in its simplest form, with no error message:

run_command || exit 1

---

As an alternative, you might want to use set -e. You might also be interested in set -o pipefail.

These are not the preferred solution, as @William has pointed out, but can be useful for getting simple scripts to throw errors:

Note that set -e is generally not considered best practice. It's semantics are extremely unexpected in the edge cases (eg, if you invoke set -e in a function), and more importantly have changed dramatically with different versions of the shell. It is far better to explicitly invoke exit by running cmd || exit

You can use set -e to cause bash to bail out if a command returns non-zero, and set +e to disable this behaviour.

set: set [-abefhkmnptuvxBCHP] [-o option-name] [--] [arg ...]
    Set or unset values of shell options and positional parameters.

    Change the value of shell attributes and positional parameters, or
    display the names and values of shell variables.

    Options:
      [...]
      -e  Exit immediately if a command exits with a non-zero status.
      [...]
      -o option-name
          Set the variable corresponding to option-name:
              [...]
              pipefail     the return value of a pipeline is the status of
                           the last command to exit with a non-zero status,
                           or zero if no command exited with a non-zero status
              [...]

To make use of this, you must enable the option before it would be required.

For example:

# disable 'exit immediately' (the default)
set +e

echo "running false..."
false
echo "we're still running"

# enable 'exit immediately'
set -e

echo "running false..."
false
echo "this should never get printed"

set -o pipefail must be used in conjunction with set -e:

# enable 'exit immediately'
set -e

# disable 'pipefail' (the default)
set +o pipefail

echo "running false | true..."
false | true
echo "we're still running (only the last exit status is considered)"

# enable 'pipefail'
set -o pipefail

echo "running false | true..."
false | true
echo "this should never get printed"