newgrp - change effective group ID sg - execute command with different group ID


newgrp [-l] [group] sg group -c command


The newgrp command changes the user’s real and effetive group ID by replacing the current shell with a new shell. A new shell is launched even if an error occours.

A password is requested if the group has a password and the user is not listed in the group file as being a member of that group. The password can be changed with the gpasswd(1) command.

If the new effective group ID is not in the supplementary group list, newgrp will add the new group ID to the supplementary list, too.

With no operands and options, newgrp changes the user’s group IDs (real and effective) back to the group specified in password and group file.

The sg command works like the newgrp command, except that it executes the given command with /bin/sh and upon exit the group ID of the current shell is not changed.


-l, --login
 reinitialize the environment as if the user logged in.
--help Print a help list.
-u, --usage
 Print a short usage message.
-v, --version
 Print program version.


gpasswd(1), group(5), passwd(1), passwd(5), su(1)


Thorsten Kukuk <>

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