newgrp - log in to a new group
sg - execute command as different group ID
newgrp [-] [group]
sg [-] [group [[-c] command]]
newgrp is used to change the current group ID during a login session.
If the optional - flag is given, the user’s environment will be reini-
tialized as though the user had logged in, otherwise the current envi-
ronment, including current working directory, remains unchanged.
newgrp changes the current real group ID to the named group, or to the
default group listed in /etc/passwd if no group name is given. newgrp
also tries to add the group to the user groupset. If not root, the user
will be prompted for a password if she do not have a password and the
group does, or if the user is not listed as a member and the group has
a password. The user will be denied access if the group password is
empty and the user is not listed as a member. If compiled with SHADOW-
PWD (respectively SHADOWGRP) defined, the password of the user (respec-
tively, the password and the members of the group) will be overwritten
by the value defined in /etc/shadow (respectively in /etc/gshadow) if
an entry exists for this user (resp. group).
The sg command works similar to newgrp but accepts a command. The com-
mand will be executed with the /bin/sh shell. With most shells you may
run sg from, you need to enclose multi-word commands in quotes.
Another difference between newgrp and sg is that some shells treat new-
grp specially, replacing themselves with a new instance of a shell that
newgrp creates. This doesn’t happen with sg, so upon exit from a sg
command you are returned to your previous group ID.
/etc/passwd - user account information
/etc/shadow - secure user account information
/etc/group - group account information
/etc/gshadow - shadow group file
id(1), login(1), su(1), gpasswd(1), group(5), gshadow(5)
Julianne Frances Haugh <email@example.com>
Man(1) output converted with