unbound variable check makes it impossible to optionally take into account an environment variable

[schlichtanders]

Hi,
I today tried to migrate some adhoc scripts to a justfile and arrived at a bug/crucially missing feature/some misunderstanding:

test:
   #!/usr/bin/env bash
   set -euo pipefail
   if [[ -z "$MYVARIABLE" ]]; then
      DEFAULT="somedefault"
   else
      DEFAULT="$MYVARIABLE"
   fi

This raises the unbound variable error if MYVARIABLE does not exist as a environment variable
I would also be happy to know about a workaround (setting the environment variable manually before to empty is NOT a workaround for me - I want the final just call to be convenient)

[laniakea64]

From man bash -

-u Treat unset variables and parameters other than the special parameters "@" and "*" as an error when
performing parameter expansion. If expansion is attempted on an unset variable or parameter, the
shell prints an error message, and, if not interactive, exits with a non-zero status.

So try removing u from the set line?

[casey]

You can also leave -u and use -z "${VAR:-}". ${VAR:-} will be empty if VAR is unset or empty, but won't trigger the unset variable check.

[schlichtanders]

thank you so much for your help! that is it indeed!