Question

I have a bash program that will write to an output file. This file may or may not exist, but the script must check permissions and fail early. I can’t find an elegant way to make this happen. Here’s what I have tried.

set +e
touch $file
set -e

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

I keep set -e on for this script so it fails if there is ever an error on any line. Is there an easier way to do the above script?

Answer 1

Rather than check $? on a different line, check the return value immediately like this:

touch file || exit

As long as your umask doesn’t restrict the write bit from being set, you can just rely on the return value of touch