The
newgrp command changes a user to a new primary group (real and effective group ID) by starting a new shell. The user remains logged in and the current directory and file creation mask remain unchanged. The user is always given a new shell even if the primary group change fails.
The
newgrp command accepts the following options:
-l
The environment is changed to what would be expected if the user actually logged in again. This simulates a full login.
The
group is a group name or non-negative numeric group ID from the group database. The real and effective group IDs are set to
group or the group ID associated with the group name.
If
group is not specified,
newgrp restores the user's real and effective group IDs to the user's primary group specified in the password database. The user's supplementary group IDs are restored to the set specified for the user in the group database.
If the user is not a member of the specified group, and the group requires a password, the user will be prompted for the group password.