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.Dd February 8, 2013 26.Dt NEWGRP 1 27.Os 28.Sh NAME 29.Nm newgrp 30.Nd change to a new group 31.Sh SYNOPSIS 32.Nm 33.Op Fl l 34.Op Ar group 35.Sh DESCRIPTION 36The 37.Nm 38utility creates a new shell execution environment with modified 39real and effective group IDs. 40.Pp 41The options are as follows: 42.Bl -tag -width indent 43.It Fl l 44Simulate a full login. 45The environment and umask are set to what would be expected if the user 46actually logged in again. 47.El 48.Pp 49If the 50.Ar group 51operand is present, a new shell is started with the specified effective 52and real group IDs. 53The user will be prompted for a password if they are not a member of the 54specified group. 55.Pp 56Otherwise, the real, effective and supplementary group IDs are restored to 57those from the current user's password database entry. 58.Sh EXIT STATUS 59The 60.Nm 61utility attempts to start the shell regardless of whether group IDs 62were successfully changed. 63.Pp 64If an error occurs and the shell cannot be started, 65.Nm 66exits >0. 67Otherwise, the exit status of 68.Nm 69is the exit status of the shell. 70.Sh SEE ALSO 71.Xr csh 1 , 72.Xr groups 1 , 73.Xr login 1 , 74.Xr sh 1 , 75.Xr su 1 , 76.Xr umask 1 , 77.Xr group 5 , 78.Xr passwd 5 , 79.Xr environ 7 80.Sh STANDARDS 81The 82.Nm 83utility conforms to 84.St -p1003.1-2001 . 85.Sh HISTORY 86A 87.Nm 88utility appeared in 89.At v6 . 90.Sh BUGS 91For security reasons, the 92.Nm 93utility is normally installed without the setuid bit. 94To enable it, run the following command: 95.Bd -literal -offset indent 96chmod u+s /usr/bin/newgrp 97.Ed 98.Pp 99Group passwords are inherently insecure as there is no way to stop 100users obtaining the password hash from the group database. 101Their use is discouraged. 102Instead, users should simply be added to the necessary groups. 103