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 1.10 1998/05/19 06:24:50 jkoshy 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 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 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.Sh DIAGNOSTICS 101The 102.Nm 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 from the sum of 107one or more of the following values: 108.Pp 109.Bl -tag -width 6n -compact -offset indent 110.It Li 4000 111(the set-user-ID-on-execution bit) Executable files with this bit set 112will run with effective uid set to the uid of the file owner. 113Directories with the set-user-id bit set will force all files and 114sub-directories created in them to be owned by the directory owner 115and not by the uid of the creating process, if the underlying file 116system supports this feature: see 117.Xr chmod 2 118and the 119.Ar suiddir 120option to 121.Xr mount 1 . 122.It Li 2000 123(the set-group-ID-on-execution bit) Executable files with this bit set 124will run with effective gid set to the gid of the file owner. 125.It Li 1000 126(the sticky bit) 127When set on a directory, unprivileged users can delete and rename 128only those files in the directory that are owned by them, regardless of 129the permissions on the directory. Under FreeBSD, the sticky bit is 130ignored for executable files and may only be set for directories (see 131.Xr sticky 8 ). 132.It Li 0400 133Allow read by owner. 134.It Li 0200 135Allow write by owner. 136.It Li 0100 137For files, allow execution by owner. For directories, allow the owner to 138search in the directory. 139.It Li 0040 140Allow read by group members. 141.It Li 0020 142Allow write by group members. 143.It Li 0010 144For files, allow execution by group members. For directories, allow 145group members to search in the directory. 146.It Li 0004 147Allow read by others. 148.It Li 0002 149Allow write by others. 150.It Li 0001 151For files, allow execution by others. For directories allow others to 152search in the directory. 153.El 154.Pp 155For example, the absolute mode that permits read, write and execute by 156the owner, read and execute by group members, read and execute by 157others, and no set-uid or set-gid behaviour is 755 158(400+200+100+040+010+004+001). 159.Pp 160The symbolic mode is described by the following grammar: 161.Bd -literal -offset indent 162mode ::= clause [, clause ...] 163clause ::= [who ...] [action ...] last_action 164action ::= op [perm ...] 165last_action ::= op [perm ...] 166who ::= a | u | g | o 167op ::= + | \- | = 168perm ::= r | s | t | w | x | X | u | g | o 169.Ed 170.Pp 171The 172.Ar who 173symbols ``u'', ``g'', and ``o'' specify the user, group, and other parts 174of the mode bits, respectively. 175The 176.Ar who 177symbol ``a'' is equivalent to ``ugo''. 178.Pp 179.ne 1i 180The 181.Ar perm 182symbols represent the portions of the mode bits as follows: 183.Pp 184.Bl -tag -width Ds -compact -offset indent 185.It r 186The read bits. 187.It s 188The set-user-ID-on-execution and set-group-ID-on-execution bits. 189.It t 190The sticky bit. 191.It w 192The write bits. 193.It x 194The execute/search bits. 195.It X 196The execute/search bits if the file is a directory or any of the 197execute/search bits are set in the original (unmodified) mode. 198Operations with the 199.Ar perm 200symbol ``X'' are only meaningful in conjunction with the 201.Ar op 202symbol ``+'', and are ignored in all other cases. 203.It u 204The user permission bits in the mode of the original file. 205.It g 206The group permission bits in the mode of the original file. 207.It o 208The other permission bits in the mode of the original file. 209.El 210.Pp 211The 212.Ar op 213symbols represent the operation performed, as follows: 214.Bl -tag -width 4n 215.It + 216If no value is supplied for 217.Ar perm , 218the ``+'' operation has no effect. 219If no value is supplied for 220.Ar who , 221each permission bit specified in 222.Ar perm , 223for which the corresponding bit in the file mode creation mask 224is clear, is set. 225Otherwise, the mode bits represented by the specified 226.Ar who 227and 228.Ar perm 229values are set. 230.It \&\- 231If no value is supplied for 232.Ar perm , 233the ``\-'' operation has no effect. 234If no value is supplied for 235.Ar who , 236each permission bit specified in 237.Ar perm , 238for which the corresponding bit in the file mode creation mask 239is clear, is cleared. 240Otherwise, the mode bits represented by the specified 241.Ar who 242and 243.Ar perm 244values are cleared. 245.It = 246The mode bits specified by the 247.Ar who 248value are cleared, or, if no who value is specified, the owner, group 249and other mode bits are cleared. 250Then, if no value is supplied for 251.Ar who , 252each permission bit specified in 253.Ar perm , 254for which the corresponding bit in the file mode creation mask 255is clear, is set. 256Otherwise, the mode bits represented by the specified 257.Ar who 258and 259.Ar perm 260values are set. 261.El 262.Pp 263Each 264.Ar clause 265specifies one or more operations to be performed on the mode 266bits, and each operation is applied to the mode bits in the 267order specified. 268.Pp 269Operations upon the other permissions only (specified by the symbol 270``o'' by itself), in combination with the 271.Ar perm 272symbols ``s'' or ``t'', are ignored. 273.Sh EXAMPLES 274.Bl -tag -width "u=rwx,go=u-w" -compact 275.It Li 644 276make a file readable by anyone and writable by the owner only. 277.Pp 278.It Li go-w 279deny write permission to group and others. 280.Pp 281.It Li =rw,+X 282set the read and write permissions to the usual defaults, but 283retain any execute permissions that are currently set. 284.Pp 285.It Li +X 286make a directory or file searchable/executable by everyone if it is 287already searchable/executable by anyone. 288.Pp 289.It Li 755 290.It Li u=rwx,go=rx 291.It Li u=rwx,go=u-w 292make a file readable/executable by everyone and writable by the owner only. 293.Pp 294.It Li go= 295clear all mode bits for group and others. 296.Pp 297.It Li g=u-w 298set the group bits equal to the user bits, but clear the group write bit. 299.El 300.Sh BUGS 301There's no 302.Ar perm 303option for the naughty bits. 304.Sh SEE ALSO 305.Xr chflags 1 , 306.Xr install 1 , 307.Xr mount 1 , 308.Xr chmod 2 , 309.Xr stat 2 , 310.Xr umask 2 , 311.Xr fts 3 , 312.Xr setmode 3 , 313.Xr symlink 7 , 314.Xr chown 8 , 315.Xr sticky 8 316.Sh STANDARDS 317The 318.Nm 319utility is expected to be 320.St -p1003.2 321compatible with the exception of the 322.Ar perm 323symbols 324.Dq t 325and 326.Dq X 327which are not included in that standard. 328.Sh HISTORY 329A 330.Nm 331command appeared in 332.At v1 . 333