How To Grep the Standard Error

The following example:

  1. Executes perl Makefile.PL and saves the standard error of this command to a variable.

  2. Echoes the standard error so that it appears normal in the Attune output.

  3. Searches the standard error for a specific message and fails the step with an exit code of 34 if found.

The standard output is printed as normal.

1{ stderr="$( { perl Makefile.PL; } 2>&1 1>&3 3>&- )"; } 3>&1
2IFS=$'\n' echo "${stderr}" 1>&2
3grep -q "Warning: prerequisite" <<< ${stderr} && exit 34