.\"	$NetBSD: newgrp.1,v 1.3 2008/05/02 21:48:18 martin Exp $
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.\" Copyright (c) 2007, The NetBSD Foundation.
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.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Brian Ginsbach.
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.Dd June 6, 2007
.Dt NEWGRP 1
.Os
.Sh NAME
.Nm newgrp
.Nd change to a new primary group
.Sh SYNOPSIS
.Nm
.Op Fl l
.Op Ar group
.Sh DESCRIPTION
The
.Nm
command changes a user to a new primary group
.Pq 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.
.Pp
The
.Nm
command accepts the following options:
.Bl -tag -width indent
.It Fl l
The environment is changed to what would be expected if the user
actually logged in again.
This simulates a full login.
.El
.Pp
The
.Ar group
is a group name or non-negative numeric group ID from the group database.
The real and effective group IDs are set to
.Ar group
or the group ID associated with the group name.
.Pp
If
.Ar group
is not specified,
.Nm
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.
.Pp
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.
.Sh EXIT STATUS
If a new shell is started the exit status is the exit status of the shell.
Otherwise the exit status will be \*[Gt]0.
.Sh FILES
.Bl -tag -width /etc/master.passwd -compact
.It Pa /etc/group
The group database
.It Pa /etc/master.passwd
The user database
.It Pa /etc/passwd
A Version 7 format password file
.El
.Sh SEE ALSO
.Xr csh 1 ,
.Xr groups 1 ,
.Xr login 1 ,
.Xr sh 1 ,
.Xr su 1 ,
.Xr umask 2 ,
.Xr group 5 ,
.Xr passwd 5 ,
.Xr environ 7
.Sh STANDARDS
The
.Nm
command conforms to
.St -p1003.1-2001 .
.Sh HISTORY
A
.Nm
command appeared in
.At v6 .
A
.Nm
command appeared in
.Nx 5.0 .
.Sh BUGS
There is no convenient way to enter a password into
.Pa /etc/group .
The use of group passwords is strongly discouraged
since they are inherently insecure.
It is not possible to stop users from obtaining the encrypted
password from the group database.