newgrp
—
change to a new 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),
environ(7)
The
newgrp
utility conforms to
IEEE Std 1003.1-2001
(“POSIX.1”).
A
newgrp
utility appeared in
Version 6 AT&T UNIX.
For security reasons, the
newgrp
utility is
normally installed without the setuid bit. To enable it, run the following
command:
chmod u+s /usr/bin/newgrp
Group passwords are inherently insecure as there is no way to stop users
obtaining the password hash from the group database. Their use is discouraged.
Instead, users should simply be added to the necessary groups.