Exit a Script On Error

Solution 1:

If you put set -e in a script, the script will terminate as soon as any command inside it fails (i.e. as soon as any command returns a nonzero status). This doesn't let you write your own message, but often the failing command's own messages are enough.

The advantage of this approach is that it's automatic: you don't run the risk of forgetting to deal with an error case.

Commands whose status is tested by a conditional (such as if, && or ||) do not terminate the script (otherwise the conditional would be pointless). An idiom for the occasional command whose failure doesn't matter is command-that-may-fail || true. You can also turn set -e off for a part of the script with set +e.

Solution 2:

Are you looking for exit?

This is the best bash guide around. http://tldp.org/LDP/abs/html/

In context:

if jarsigner -verbose -keystore $keyst -keystore $pass $jar_file $kalias
then
    echo $jar_file signed sucessfully
else
    echo ERROR: Failed to sign $jar_file. Please recheck the variables 1>&2
    exit 1 # terminate and indicate error
fi

...

Solution 3:

If you want to be able to handle an error instead of blindly exiting, instead of using set -e, use a trap on the ERR pseudo signal.

#!/bin/bash
f () {
    errorCode=$? # save the exit code as the first thing done in the trap function
    echo "error $errorCode"
    echo "the command executing at the time of the error was"
    echo "$BASH_COMMAND"
    echo "on line ${BASH_LINENO[0]}"
    # do some error handling, cleanup, logging, notification
    # $BASH_COMMAND contains the command that was being executed at the time of the trap
    # ${BASH_LINENO[0]} contains the line number in the script of that command
    # exit the script or return to try again, etc.
    exit $errorCode  # or use some other value or do return instead
}
trap f ERR
# do some stuff
false # returns 1 so it triggers the trap
# maybe do some other stuff

Other traps can be set to handle other signals, including the usual Unix signals plus the other Bash pseudo signals RETURN and DEBUG.