NEWGRP(1) General Commands Manual NEWGRP(1)
newgrp – change to a new group
newgrp [-l] [group]
The newgrp utility creates a new shell execution environment with modified
real and effective group IDs.
The options are as follows:
-l Simulate a full login. The environment and umask are set to what
would be expected if the user actually logged in again.
If the group operand is present, a new shell is started with the specified
effective and real group IDs. The user will be prompted for a password if
they are not a member of the specified group.
Otherwise, the real, effective and supplementary group IDs are restored to
those from the current user's password database entry.
The newgrp utility attempts to start the shell regardless of whether group
IDs were successfully changed.
If an error occurs and the shell cannot be started, newgrp exits >0.
Otherwise, the exit status of newgrp is the exit status of the shell.
csh(1), groups(1), login(1), sh(1), su(1), umask(1), group(5), passwd(5),
The newgrp utility conforms to IEEE Std 1003.1-2001 (“POSIX.1”).
A newgrp utility appeared in Version 6 AT&T UNIX.
Group passwords are inherently insecure as there is no way to stop users
obtaining the crypted passwords from the group database. Their use is
macOS 12.1 May 23, 2002 macOS 12.1