To test a shell script called myscript, the environment variable FOOBAR must be removed temporarily. How can this be done?

`unset -v FOOBAR` would permanently remove the `FOOBAR` variable from the current shell's environment, which is not a temporary removal for only the script.

`set -a FOOBAR=""` would set the `FOOBAR` variable to an empty string and mark it for export, not remove or unset it.

The `env -u FOOBAR myscript` command runs `myscript` with the `FOOBAR` environment variable unset specifically for the duration of that command. This allows testing the script in an isolated environment without affecting the calling shell's environment.

`env -i FOOBAR myscript` would execute `myscript` in an *empty* environment, meaning all inherited variables are removed, which is too broad if only `FOOBAR` needs to be unset while others remain.