basename complains about missing operand using unshare

If I try to create namespaces, basename complains about missing operand: sudo unshare --mount --ipc --uts --pid --fork --user /bin/bash basename: missing operand Try 'basename --help' for more information. I even tried with bash --norc with no luck. Why does this error occur? And how do I fix it? ## UPDATE 1 When I said that "I even tried with bash --norc with no luck." I meant that I run bash --norc and then sudo unshare.... but that it works: sudo unshare --mount --ipc --uts --pid --fork --user /bin/bash --norc --noprofile I wonder anyway why. Because I have basename in .bashrc only into functions, and disabling those functions it outputs the same error