Detecting command failures in bash

Suppose you want to detect weather all the commands executed successfully in your script:

#!/usr/bin/env bash





# make sure the script exits as soon

# as first error is encountered

set -e

success=0



# call our function on (nice) exit of the script

trap on_exit 0



on_exit(){

    if (( success )); then

        echo 'all commands executed successfully'

    else

        echo 'at least one command failed'

    fi

}



# your commands go here

true

#false



# if the execution come to here means 

# set -e did NOT exit the script

success=1

Some notes:

• Uncomment "false" to see the code work
• set -e depends on the commands behaving nicely and returning a non zero exit code on error. Just about all standard tools do this.
• The on_exit will NOT be called if your script was interrupted with SIGKILL
• Dummy echo commands are useless :), you should replace them with something like mailing/logging