.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved 
.TH "CHGRP" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\" chgrp 
.SH NAME
chgrp \- change the file group ownership
.SH SYNOPSIS
.LP
\fBchgrp\fP \fB[\fP\fB-hR\fP\fB]\fP \fIgroup file\fP \fB...
.br
.sp
chgrp -R\fP \fB[\fP\fB-H | -L | -P\fP \fB]\fP \fIgroup file\fP \fB...
.br
\fP
.SH DESCRIPTION
.LP
The \fIchgrp\fP utility shall set the group ID of the file named by
each \fIfile\fP operand to the group ID specified by the
\fIgroup\fP operand.
.LP
For each \fIfile\fP operand, or, if the \fB-R\fP option is used, each
file encountered while walking the directory trees
specified by the \fIfile\fP operands, the \fIchgrp\fP utility shall
perform actions equivalent to the \fIchown\fP() function defined in
the System Interfaces volume of IEEE\ Std\ 1003.1-2001,
called with the following arguments:
.IP " *" 3
The \fIfile\fP operand shall be used as the \fIpath\fP argument.
.LP
.IP " *" 3
The user ID of the file shall be used as the \fIowner\fP argument.
.LP
.IP " *" 3
The specified group ID shall be used as the \fIgroup\fP argument.
.LP
.LP
Unless \fIchgrp\fP is invoked by a process with appropriate privileges,
the set-user-ID and set-group-ID bits of a regular file
shall be cleared upon successful completion; the set-user-ID and set-group-ID
bits of other file types may be cleared.
.SH OPTIONS
.LP
The \fIchgrp\fP utility shall conform to the Base Definitions volume
of IEEE\ Std\ 1003.1-2001, Section 12.2, Utility Syntax Guidelines.
.LP
The following options shall be supported by the implementation:
.TP 7
\fB-h\fP
If the system supports group IDs for symbolic links, for each \fIfile\fP
operand that names a file of type symbolic link,
\fIchgrp\fP shall attempt to set the group ID of the symbolic link
instead of the file referenced by the symbolic link. If the
system does not support group IDs for symbolic links, for each \fIfile\fP
operand that names a file of type symbolic link,
\fIchgrp\fP shall do nothing more with the current file and shall
go on to any remaining files.
.TP 7
\fB-H\fP
If the \fB-R\fP option is specified and a symbolic link referencing
a file of type directory is specified on the command line,
\fIchgrp\fP shall change the group of the directory referenced by
the symbolic link and all files in the file hierarchy below
it.
.TP 7
\fB-L\fP
If the \fB-R\fP option is specified and a symbolic link referencing
a file of type directory is specified on the command line
or encountered during the traversal of a file hierarchy, \fIchgrp\fP
shall change the group of the directory referenced by the
symbolic link and all files in the file hierarchy below it.
.TP 7
\fB-P\fP
If the \fB-R\fP option is specified and a symbolic link is specified
on the command line or encountered during the traversal
of a file hierarchy, \fIchgrp\fP shall change the group ID of the
symbolic link if the system supports this operation. The
\fIchgrp\fP utility shall not follow the symbolic link to any other
part of the file hierarchy.
.TP 7
\fB-R\fP
Recursively change file group IDs. For each \fIfile\fP operand that
names a directory, \fIchgrp\fP shall change the group of
the directory and all files in the file hierarchy below it. Unless
a \fB-H\fP, \fB-L\fP, or \fB-P\fP option is specified, it is
unspecified which of these options will be used as the default.
.sp
.LP
Specifying more than one of the mutually-exclusive options \fB-H\fP,
\fB-L\fP, and \fB-P\fP shall not be considered an error.
The last option specified shall determine the behavior of the utility.
.SH OPERANDS
.LP
The following operands shall be supported:
.TP 7
\fIgroup\fP
A group name from the group database or a numeric group ID. Either
specifies a group ID to be given to each file named by one
of the \fIfile\fP operands. If a numeric \fIgroup\fP operand exists
in the group database as a group name, the group ID number
associated with that group name is used as the group ID.
.TP 7
\fIfile\fP
A pathname of a file whose group ID is to be modified.
.sp
.SH STDIN
.LP
Not used.
.SH INPUT FILES
.LP
None.
.SH ENVIRONMENT VARIABLES
.LP
The following environment variables shall affect the execution of
\fIchgrp\fP:
.TP 7
\fILANG\fP
Provide a default value for the internationalization variables that
are unset or null. (See the Base Definitions volume of
IEEE\ Std\ 1003.1-2001, Section 8.2, Internationalization Variables
for
the precedence of internationalization variables used to determine
the values of locale categories.)
.TP 7
\fILC_ALL\fP
If set to a non-empty string value, override the values of all the
other internationalization variables.
.TP 7
\fILC_CTYPE\fP
Determine the locale for the interpretation of sequences of bytes
of text data as characters (for example, single-byte as
opposed to multi-byte characters in arguments).
.TP 7
\fILC_MESSAGES\fP
Determine the locale that should be used to affect the format and
contents of diagnostic messages written to standard
error.
.TP 7
\fINLSPATH\fP
Determine the location of message catalogs for the processing of \fILC_MESSAGES
\&.\fP 
.sp
.SH ASYNCHRONOUS EVENTS
.LP
Default.
.SH STDOUT
.LP
Not used.
.SH STDERR
.LP
The standard error shall be used only for diagnostic messages.
.SH OUTPUT FILES
.LP
None.
.SH EXTENDED DESCRIPTION
.LP
None.
.SH EXIT STATUS
.LP
The following exit values shall be returned:
.TP 7
\ 0
The utility executed successfully and all requested changes were made.
.TP 7
>0
An error occurred.
.sp
.SH CONSEQUENCES OF ERRORS
.LP
Default.
.LP
\fIThe following sections are informative.\fP
.SH APPLICATION USAGE
.LP
Only the owner of a file or the user with appropriate privileges may
change the owner or group of a file.
.LP
Some implementations restrict the use of \fIchgrp\fP to a user with
appropriate privileges when the \fIgroup\fP specified is
not the effective group ID or one of the supplementary group IDs of
the calling process.
.SH EXAMPLES
.LP
None.
.SH RATIONALE
.LP
The System V and BSD versions use different exit status codes. Some
implementations used the exit status as a count of the
number of errors that occurred; this practice is unworkable since
it can overflow the range of valid exit status values. The
standard developers chose to mask these by specifying only 0 and >0
as exit values.
.LP
The functionality of \fIchgrp\fP is described substantially through
references to \fIchown\fP(). In this way, there is no duplication
of effort required for describing the
interactions of permissions, multiple groups, and so on.
.SH FUTURE DIRECTIONS
.LP
None.
.SH SEE ALSO
.LP
\fIchmod\fP() , \fIchown\fP() , the System Interfaces volume of
IEEE\ Std\ 1003.1-2001, \fIchown\fP()
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .