How to add additional info to stderr output when bash script calls another application

Question

On Ubuntu, I have a bash script that runs an application.

When that app seg faults, I get some info in std err, e.g.

/usr/local/foo/script.sh: line 21: 494382 Segmentation fault      (core dumped) appplication_name_and_arguments_here

Std err is being redirected to a file, which is then going into a log monitoring system.

What I'd like to do is augment the stderr content with more helpful info when this happens, e.g. some environment variables, and a timestamp.

How can I do this?

Thanks.

pjh · Answer 1 · 2022-03-01T17:27:38.980

You could try putting an ERR trap in script.sh. Try putting this close to the top of it as a start:

set -o errtrace

trap err_trap ERR

function err_trap
{
    printf 'ERR trap:\n' >&2
    printf '    PATH=%s\n' "$PATH" >&2
    printf '    PWD=%s\n' "$PWD" >&2
    printf '    date: %s\n' "$(date)" >&2

    exit 1
}

That's very rough and ready, but hopefully you will be able to enhance it to do what you want.

See the trap section in the Bash Reference Manual for information about trap.
See Mysterious LINENO in bash trap ERR for (somewhat buried) examples of potentially useful things that you can do with an ERR trap.
See What does set -o errtrace do in a shell script? for an explanation of the set -o errtrace.

How to add additional info to stderr output when bash script calls another application

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