1.\" Copyright (c) 2002 Tim J. Robbins. 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 13.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 14.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 17.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23.\" SUCH DAMAGE. 24.\" 25.\" $FreeBSD: src/usr.bin/newgrp/newgrp.1,v 1.2 2002/05/30 13:57:35 ru Exp $ 26.\" 27.Dd November 24, 2013 28.Dt NEWGRP 1 29.Os 30.Sh NAME 31.Nm newgrp 32.Nd change to a new group 33.Sh SYNOPSIS 34.Nm 35.Op Fl l 36.Op Ar group 37.Sh DESCRIPTION 38The 39.Nm 40utility creates a new shell execution environment with modified 41real and effective group IDs. 42.Pp 43The options are as follows: 44.Bl -tag -width indent 45.It Fl l 46Simulate a full login. 47The environment and umask are set to what would be expected if the user 48actually logged in again. 49.El 50.Pp 51If the 52.Ar group 53operand is present, a new shell is started with the specified effective 54and real group IDs. 55The user will be prompted for a password if they are not a member of the 56specified group. 57.Pp 58Otherwise, the real, effective and supplementary group IDs are restored to 59those from the current user's password database entry. 60.Sh EXIT STATUS 61The 62.Nm 63utility attempts to start the shell regardless of whether group IDs 64were successfully changed. 65.Pp 66If an error occurs and the shell cannot be started, 67.Nm 68exits >0. 69Otherwise, the exit status of 70.Nm 71is the exit status of the shell. 72.Sh SEE ALSO 73.Xr csh 1 , 74.Xr groups 1 , 75.Xr login 1 , 76.Xr sh 1 , 77.Xr su 1 , 78.Xr umask 1 , 79.Xr group 5 , 80.Xr passwd 5 , 81.Xr environ 7 82.Sh STANDARDS 83The 84.Nm 85utility conforms to 86.St -p1003.1-2001 . 87.Sh HISTORY 88A 89.Nm 90utility appeared in 91.At v6 . 92.Sh BUGS 93For security reasons, the 94.Nm 95utility is normally installed without the setuid bit. 96To enable it, run the following command: 97.Bd -literal -offset indent 98chmod u+s /usr/bin/newgrp 99.Ed 100.Pp 101Group passwords are inherently insecure as there is no way to stop 102users obtaining the password hash from the group database. 103Their use is discouraged. 104Instead, users should simply be added to the necessary groups. 105