> 3. even `adduser` will not allow it by default 5. useradd does allow it (as noted in a comment). 6. Local users, and the utilities that create them, are not

> 3. even `adduser` will not allow it by default 5. useradd does allow it (as noted in a comment). 6. Local users, and the utilities that create them, are not the only source, there things like LDAP and AD. 7. POSIX allows it: * https://github.com/systemd/systemd/issues/6237#issuecomment-312456526 https://github.com/systemd/systemd/issues/6237#issuecomment-...