1.\" Copyright (c) 1989, 1990, 1993, 1994 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" the Institute of Electrical and Electronics Engineers, Inc. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. All advertising materials mentioning features or use of this software 16.\" must display the following acknowledgement: 17.\" This product includes software developed by the University of 18.\" California, Berkeley and its contributors. 19.\" 4. Neither the name of the University nor the names of its contributors 20.\" may be used to endorse or promote products derived from this software 21.\" without specific prior written permission. 22.\" 23.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33.\" SUCH DAMAGE. 34.\" 35.\" @(#)chmod.1 8.4 (Berkeley) 3/31/94 36.\" $Id: chmod.1,v 1.3 1996/02/16 00:08:53 joerg Exp $ 37.\" 38.Dd March 31, 1994 39.Dt CHMOD 1 40.Os 41.Sh NAME 42.Nm chmod 43.Nd change file modes 44.Sh SYNOPSIS 45.Nm chmod 46.Oo 47.Fl R 48.Op Fl H | Fl L | Fl P 49.Oc 50.Ar mode 51.Ar file ... 52.Sh DESCRIPTION 53The 54.Nm chmod 55utility modifies the file mode bits of the listed files 56as specified by the 57.Ar mode 58operand. 59.Pp 60The options are as follows: 61.Bl -tag -width Ds 62.It Fl H 63If the 64.Fl R 65option is specified, symbolic links on the command line are followed. 66(Symbolic links encountered in the tree traversal are not followed.) 67.It Fl L 68If the 69.Fl R 70option is specified, all symbolic links are followed. 71.It Fl P 72If the 73.Fl R 74option is specified, no symbolic links are followed. 75.It Fl R 76Change the modes of the file hierarchies rooted in the files 77instead of just the files themselves. 78.El 79.Pp 80Symbolic links do not have modes, so unless the 81.Fl H 82or 83.Fl L 84option is set, 85.Nm chmod 86on a symbolic link always succeeds and has no effect. 87The 88.Fl H , 89.Fl L 90and 91.Fl P 92options are ignored unless the 93.Fl R 94option is specified. 95In addition, these options override each other and the 96command's actions are determined by the last one specified. 97.Pp 98Only the owner of a file or the super-user is permitted to change 99the mode of a file. 100.Pp 101The 102.Nm chmod 103utility exits 0 on success, and >0 if an error occurs. 104.Sh MODES 105Modes may be absolute or symbolic. 106An absolute mode is an octal number constructed by 107.Ar or-ing 108the following values: 109.Pp 110.Bl -tag -width 6n -compact -offset indent 111.It Li 4000 112set-user-ID-on-execution 113.It Li 2000 114set-group-ID-on-execution 115.It Li 1000 116sticky bit, see chmod(2) 117.It Li 0400 118read by owner 119.It Li 0200 120write by owner 121.It Li 0100 122execute (or search for directories) by owner 123.It Li 0070 124read, write, execute/search by group 125.It Li 0007 126read, write, execute/search by others 127.El 128.Pp 129The read, write, and execute/search values for group and others 130are encoded as described for owner. 131.Pp 132The symbolic mode is described by the following grammar: 133.Bd -literal -offset indent 134mode ::= clause [, clause ...] 135clause ::= [who ...] [action ...] last_action 136action ::= op [perm ...] 137last_action ::= op [perm ...] 138who ::= a | u | g | o 139op ::= + | \- | = 140perm ::= r | s | t | w | x | X | u | g | o 141.Ed 142.Pp 143The 144.Ar who 145symbols ``u'', ``g'', and ``o'' specify the user, group, and other parts 146of the mode bits, respectively. 147The 148.Ar who 149symbol ``a'' is equivalent to ``ugo''. 150.Pp 151.ne 1i 152The 153.Ar perm 154symbols represent the portions of the mode bits as follows: 155.Pp 156.Bl -tag -width Ds -compact -offset indent 157.It r 158The read bits. 159.It s 160The set-user-ID-on-execution and set-group-ID-on-execution bits. 161.It t 162The sticky bit. 163.It w 164The write bits. 165.It x 166The execute/search bits. 167.It X 168The execute/search bits if the file is a directory or any of the 169execute/search bits are set in the original (unmodified) mode. 170Operations with the 171.Ar perm 172symbol ``X'' are only meaningful in conjunction with the 173.Ar op 174symbol ``+'', and are ignored in all other cases. 175.It u 176The user permission bits in the mode of the original file. 177.It g 178The group permission bits in the mode of the original file. 179.It o 180The other permission bits in the mode of the original file. 181.El 182.Pp 183The 184.Ar op 185symbols represent the operation performed, as follows: 186.Bl -tag -width 4n 187.It + 188If no value is supplied for 189.Ar perm , 190the ``+'' operation has no effect. 191If no value is supplied for 192.Ar who , 193each permission bit specified in 194.Ar perm , 195for which the corresponding bit in the file mode creation mask 196is clear, is set. 197Otherwise, the mode bits represented by the specified 198.Ar who 199and 200.Ar perm 201values are set. 202.It \&\- 203If no value is supplied for 204.Ar perm , 205the ``\-'' operation has no effect. 206If no value is supplied for 207.Ar who , 208each permission bit specified in 209.Ar perm , 210for which the corresponding bit in the file mode creation mask 211is clear, is cleared. 212Otherwise, the mode bits represented by the specified 213.Ar who 214and 215.Ar perm 216values are cleared. 217.It = 218The mode bits specified by the 219.Ar who 220value are cleared, or, if no who value is specified, the owner, group 221and other mode bits are cleared. 222Then, if no value is supplied for 223.Ar who , 224each permission bit specified in 225.Ar perm , 226for which the corresponding bit in the file mode creation mask 227is clear, is set. 228Otherwise, the mode bits represented by the specified 229.Ar who 230and 231.Ar perm 232values are set. 233.El 234.Pp 235Each 236.Ar clause 237specifies one or more operations to be performed on the mode 238bits, and each operation is applied to the mode bits in the 239order specified. 240.Pp 241Operations upon the other permissions only (specified by the symbol 242``o'' by itself), in combination with the 243.Ar perm 244symbols ``s'' or ``t'', are ignored. 245.Sh EXAMPLES 246.Bl -tag -width "u=rwx,go=u-w" -compact 247.It Li 644 248make a file readable by anyone and writable by the owner only. 249.Pp 250.It Li go-w 251deny write permission to group and others. 252.Pp 253.It Li =rw,+X 254set the read and write permissions to the usual defaults, but 255retain any execute permissions that are currently set. 256.Pp 257.It Li +X 258make a directory or file searchable/executable by everyone if it is 259already searchable/executable by anyone. 260.Pp 261.It Li 755 262.It Li u=rwx,go=rx 263.It Li u=rwx,go=u-w 264make a file readable/executable by everyone and writable by the owner only. 265.Pp 266.It Li go= 267clear all mode bits for group and others. 268.Pp 269.It Li g=u-w 270set the group bits equal to the user bits, but clear the group write bit. 271.El 272.Sh BUGS 273There's no 274.Ar perm 275option for the naughty bits. 276.Sh SEE ALSO 277.Xr chflags 1 , 278.Xr install 1 , 279.Xr chmod 2 , 280.Xr stat 2 , 281.Xr umask 2 , 282.Xr fts 3 , 283.Xr setmode 3 , 284.Xr symlink 7 , 285.Xr chown 8 286.Sh STANDARDS 287The 288.Nm chmod 289utility is expected to be POSIX 1003.2 290compatible with the exception of the 291.Ar perm 292symbols 293.Dq t 294and 295.Dq X 296which are not included in that standard. 297.Sh HISTORY 298A 299.Nm 300command appeared in 301.At v1 . 302