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.\" $FreeBSD$ 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 f 48.Fl R 49.Op Fl H | Fl L | Fl P 50.Oc 51.Ar mode 52.Ar file ... 53.Sh DESCRIPTION 54The 55.Nm 56utility modifies the file mode bits of the listed files 57as specified by the 58.Ar mode 59operand. 60.Pp 61The options are as follows: 62.Bl -tag -width Ds 63.It Fl H 64If the 65.Fl R 66option is specified, symbolic links on the command line are followed. 67(Symbolic links encountered in the tree traversal are not followed.) 68.It Fl L 69If the 70.Fl R 71option is specified, all symbolic links are followed. 72.It Fl P 73If the 74.Fl R 75option is specified, no symbolic links are followed. 76.It Fl R 77Change the modes of the file hierarchies rooted in the files 78instead of just the files themselves. 79.It Fl f 80Do not display a diagnostic message if 81.Nm 82could not modify the mode for 83.Va file . 84.El 85.Pp 86Symbolic links do not have modes, so unless the 87.Fl H 88or 89.Fl L 90option is set, 91.Nm 92on a symbolic link always succeeds and has no effect. 93The 94.Fl H , 95.Fl L 96and 97.Fl P 98options are ignored unless the 99.Fl R 100option is specified. 101In addition, these options override each other and the 102command's actions are determined by the last one specified. 103.Pp 104Only the owner of a file or the super-user is permitted to change 105the mode of a file. 106.Sh DIAGNOSTICS 107The 108.Nm 109utility exits 0 on success, and >0 if an error occurs. 110.Sh MODES 111Modes may be absolute or symbolic. 112An absolute mode is an octal number constructed from the sum of 113one or more of the following values: 114.Pp 115.Bl -tag -width 6n -compact -offset indent 116.It Li 4000 117(the set-user-ID-on-execution bit) Executable files with this bit set 118will run with effective uid set to the uid of the file owner. 119Directories with the set-user-id bit set will force all files and 120sub-directories created in them to be owned by the directory owner 121and not by the uid of the creating process, if the underlying file 122system supports this feature: see 123.Xr chmod 2 124and the 125.Ar suiddir 126option to 127.Xr mount 8 . 128.It Li 2000 129(the set-group-ID-on-execution bit) Executable files with this bit set 130will run with effective gid set to the gid of the file owner. 131.It Li 1000 132(the sticky bit) 133When set on a directory, unprivileged users can delete and rename 134only those files in the directory that are owned by them, regardless of 135the permissions on the directory. Under FreeBSD, the sticky bit is 136ignored for executable files and may only be set for directories (see 137.Xr sticky 8 ). 138.It Li 0400 139Allow read by owner. 140.It Li 0200 141Allow write by owner. 142.It Li 0100 143For files, allow execution by owner. For directories, allow the owner to 144search in the directory. 145.It Li 0040 146Allow read by group members. 147.It Li 0020 148Allow write by group members. 149.It Li 0010 150For files, allow execution by group members. For directories, allow 151group members to search in the directory. 152.It Li 0004 153Allow read by others. 154.It Li 0002 155Allow write by others. 156.It Li 0001 157For files, allow execution by others. For directories allow others to 158search in the directory. 159.El 160.Pp 161For example, the absolute mode that permits read, write and execute by 162the owner, read and execute by group members, read and execute by 163others, and no set-uid or set-gid behaviour is 755 164(400+200+100+040+010+004+001). 165.Pp 166The symbolic mode is described by the following grammar: 167.Bd -literal -offset indent 168mode ::= clause [, clause ...] 169clause ::= [who ...] [action ...] last_action 170action ::= op [perm ...] 171last_action ::= op [perm ...] 172who ::= a | u | g | o 173op ::= + | \- | = 174perm ::= r | s | t | w | x | X | u | g | o 175.Ed 176.Pp 177The 178.Ar who 179symbols ``u'', ``g'', and ``o'' specify the user, group, and other parts 180of the mode bits, respectively. 181The 182.Ar who 183symbol ``a'' is equivalent to ``ugo''. 184.Pp 185.ne 1i 186The 187.Ar perm 188symbols represent the portions of the mode bits as follows: 189.Pp 190.Bl -tag -width Ds -compact -offset indent 191.It r 192The read bits. 193.It s 194The set-user-ID-on-execution and set-group-ID-on-execution bits. 195.It t 196The sticky bit. 197.It w 198The write bits. 199.It x 200The execute/search bits. 201.It X 202The execute/search bits if the file is a directory or any of the 203execute/search bits are set in the original (unmodified) mode. 204Operations with the 205.Ar perm 206symbol ``X'' are only meaningful in conjunction with the 207.Ar op 208symbol ``+'', and are ignored in all other cases. 209.It u 210The user permission bits in the mode of the original file. 211.It g 212The group permission bits in the mode of the original file. 213.It o 214The other permission bits in the mode of the original file. 215.El 216.Pp 217The 218.Ar op 219symbols represent the operation performed, as follows: 220.Bl -tag -width 4n 221.It + 222If no value is supplied for 223.Ar perm , 224the ``+'' operation has no effect. 225If no value is supplied for 226.Ar who , 227each permission bit specified in 228.Ar perm , 229for which the corresponding bit in the file mode creation mask 230is clear, is set. 231Otherwise, the mode bits represented by the specified 232.Ar who 233and 234.Ar perm 235values are set. 236.It \&\- 237If no value is supplied for 238.Ar perm , 239the ``\-'' operation has no effect. 240If no value is supplied for 241.Ar who , 242each permission bit specified in 243.Ar perm , 244for which the corresponding bit in the file mode creation mask 245is clear, is cleared. 246Otherwise, the mode bits represented by the specified 247.Ar who 248and 249.Ar perm 250values are cleared. 251.It = 252The mode bits specified by the 253.Ar who 254value are cleared, or, if no who value is specified, the owner, group 255and other mode bits are cleared. 256Then, if no value is supplied for 257.Ar who , 258each permission bit specified in 259.Ar perm , 260for which the corresponding bit in the file mode creation mask 261is clear, is set. 262Otherwise, the mode bits represented by the specified 263.Ar who 264and 265.Ar perm 266values are set. 267.El 268.Pp 269Each 270.Ar clause 271specifies one or more operations to be performed on the mode 272bits, and each operation is applied to the mode bits in the 273order specified. 274.Pp 275Operations upon the other permissions only (specified by the symbol 276``o'' by itself), in combination with the 277.Ar perm 278symbols ``s'' or ``t'', are ignored. 279.Sh EXAMPLES 280.Bl -tag -width "u=rwx,go=u-w" -compact 281.It Li 644 282make a file readable by anyone and writable by the owner only. 283.Pp 284.It Li go-w 285deny write permission to group and others. 286.Pp 287.It Li =rw,+X 288set the read and write permissions to the usual defaults, but 289retain any execute permissions that are currently set. 290.Pp 291.It Li +X 292make a directory or file searchable/executable by everyone if it is 293already searchable/executable by anyone. 294.Pp 295.It Li 755 296.It Li u=rwx,go=rx 297.It Li u=rwx,go=u-w 298make a file readable/executable by everyone and writable by the owner only. 299.Pp 300.It Li go= 301clear all mode bits for group and others. 302.Pp 303.It Li g=u-w 304set the group bits equal to the user bits, but clear the group write bit. 305.El 306.Sh BUGS 307There's no 308.Ar perm 309option for the naughty bits. 310.Sh SEE ALSO 311.Xr chflags 1 , 312.Xr install 1 , 313.Xr chmod 2 , 314.Xr stat 2 , 315.Xr umask 2 , 316.Xr fts 3 , 317.Xr setmode 3 , 318.Xr symlink 7 , 319.Xr chown 8 , 320.Xr mount 8 , 321.Xr sticky 8 322.Sh STANDARDS 323The 324.Nm 325utility is expected to be 326.St -p1003.2 327compatible with the exception of the 328.Ar perm 329symbols 330.Dq t 331and 332.Dq X 333which are not included in that standard. 334.Sh HISTORY 335A 336.Nm 337command appeared in 338.At v1 . 339