In shell scripts set -e is often used to make them more robust by stopping the script when some of the commands executed from the script exits with non-zero exit code.

It's usually easy to specify that you don't care about some of the commands succeeding by adding || true at the end.

The problem appears when you actually care about the return value, but don't want the script to stop on non-zero return code, for example:

output=$(possibly-failing-command)
if [ 0 == $? -a -n "$output" ]; then
  ...
else
  ...
fi

Here we want to both check the exit code (thus we can't use || true inside of command substitution expression) and get the output. However, if the command in command substitution fails, the whole script stops due to set -e.

Is there a clean way to prevent the script from stopping here without unsetting -e and setting it back afterwards?