chmod/chmod.1

   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: src/bin/chmod/chmod.1,v 1.33 2002/10/01 20:32:59 trhodes 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
  46 .Op Fl fhv
  47 .Op Fl R Op Fl H | L | P
  48 .Ar mode
  49 .Ar
  50 .Sh DESCRIPTION
  51 The
  52 .Nm
  53 utility modifies the file mode bits of the listed files
  54 as specified by the
  55 .Ar mode
  56 operand.
  57 .Pp
  58 The options are as follows:
  59 .Bl -tag -width Ds
  60 .It Fl H
  61 If the
  62 .Fl R
  63 option is specified, symbolic links on the command line are followed.
  64 (Symbolic links encountered in the tree traversal are not followed by
  65 default.)
  66 .It Fl L
  67 If the
  68 .Fl R
  69 option is specified, all symbolic links are followed.
  70 .It Fl P
  71 If the
  72 .Fl R
  73 option is specified, no symbolic links are followed.
  74 This is the default.
  75 .It Fl R
  76 Change the modes of the file hierarchies rooted in the files
  77 instead of just the files themselves.
  78 .It Fl f
  79 Do not display a diagnostic message if
  80 .Nm
  81 could not modify the mode for
  82 .Va file .
  83 .It Fl h
  84 If the file is a symbolic link, change the mode of the link itself
  85 rather than the file that the link points to.
  86 .It Fl v
  87 Cause
  88 .Nm
  89 to be verbose, showing filenames as the mode is modified.
  90 If the
  91 .Fl v
  92 flag is specified more than once, the old and new modes of the file
  93 will also be printed, in both octal and symbolic notation.
  94 .El
  95 .Pp
  96 The
  97 .Fl H ,
  98 .Fl L
  99 and
 100 .Fl P
 101 options are ignored unless the
 102 .Fl R
 103 option is specified.
 104 In addition, these options override each other and the
 105 command's actions are determined by the last one specified.
 106 .Pp
 107 Only the owner of a file or the super-user is permitted to change
 108 the mode of a file.
 109 .Sh DIAGNOSTICS
 110 .Ex -std
 111 .Sh MODES
 112 Modes may be absolute or symbolic.
 113 An absolute mode is an octal number constructed from the sum of
 114 one or more of the following values:
 115 .Pp
 116 .Bl -tag -width 6n -compact -offset indent
 117 .It Li 4000
 118 (the set-user-ID-on-execution bit) Executable files with this bit set
 119 will run with effective uid set to the uid of the file owner.
 120 Directories with the set-user-id bit set will force all files and
 121 sub-directories created in them to be owned by the directory owner
 122 and not by the uid of the creating process, if the underlying file
 123 system supports this feature: see
 124 .Xr chmod 2
 125 and the
 126 .Ar suiddir
 127 option to
 128 .Xr mount 8 .
 129 .It Li 2000
 130 (the set-group-ID-on-execution bit) Executable files with this bit set
 131 will run with effective gid set to the gid of the file owner.
 132 .It Li 1000
 133 (the sticky bit)
 134 See
 135 .Xr chmod 2
 136 and
 137 .Xr sticky 8 .
 138 .It Li 0400
 139 Allow read by owner.
 140 .It Li 0200
 141 Allow write by owner.
 142 .It Li 0100
 143 For files, allow execution by owner.
 144 For directories, allow the owner to
 145 search in the directory.
 146 .It Li 0040
 147 Allow read by group members.
 148 .It Li 0020
 149 Allow write by group members.
 150 .It Li 0010
 151 For files, allow execution by group members.
 152 For directories, allow
 153 group members to search in the directory.
 154 .It Li 0004
 155 Allow read by others.
 156 .It Li 0002
 157 Allow write by others.
 158 .It Li 0001
 159 For files, allow execution by others.
 160 For directories allow others to
 161 search in the directory.
 162 .El
 163 .Pp
 164 For example, the absolute mode that permits read, write and execute by
 165 the owner, read and execute by group members, read and execute by
 166 others, and no set-uid or set-gid behaviour is 755
 167 (400+200+100+040+010+004+001).
 168 .Pp
 169 The symbolic mode is described by the following grammar:
 170 .Bd -literal -offset indent
 171 mode         ::= clause [, clause ...]
 172 clause       ::= [who ...] [action ...] action
 173 action       ::= op [perm ...]
 174 who          ::= a | u | g | o
 175 op           ::= + | \- | =
 176 perm         ::= r | s | t | w | x | X | u | g | o
 177 .Ed
 178 .Pp
 179 The
 180 .Ar who
 181 symbols ``u'', ``g'', and ``o'' specify the user, group, and other parts
 182 of the mode bits, respectively.
 183 The
 184 .Ar who
 185 symbol ``a'' is equivalent to ``ugo''.
 186 .Pp
 187 The
 188 .Ar perm
 189 symbols represent the portions of the mode bits as follows:
 190 .Pp
 191 .Bl -tag -width Ds -compact -offset indent
 192 .It r
 193 The read bits.
 194 .It s
 195 The set-user-ID-on-execution and set-group-ID-on-execution bits.
 196 .It t
 197 The sticky bit.
 198 .It w
 199 The write bits.
 200 .It x
 201 The execute/search bits.
 202 .It X
 203 The execute/search bits if the file is a directory or any of the
 204 execute/search bits are set in the original (unmodified) mode.
 205 Operations with the
 206 .Ar perm
 207 symbol ``X'' are only meaningful in conjunction with the
 208 .Ar op
 209 symbol ``+'', and are ignored in all other cases.
 210 .It u
 211 The user permission bits in the original mode of the file.
 212 .It g
 213 The group permission bits in the original mode of the file.
 214 .It o
 215 The other permission bits in the original mode of the file.
 216 .El
 217 .Pp
 218 The
 219 .Ar op
 220 symbols represent the operation performed, as follows:
 221 .Bl -tag -width 4n
 222 .It +
 223 If no value is supplied for
 224 .Ar perm ,
 225 the ``+'' operation has no effect.
 226 If no value is supplied for
 227 .Ar who ,
 228 each permission bit specified in
 229 .Ar perm ,
 230 for which the corresponding bit in the file mode creation mask
 231 is clear, is set.
 232 Otherwise, the mode bits represented by the specified
 233 .Ar who
 234 and
 235 .Ar perm
 236 values are set.
 237 .It \&\-
 238 If no value is supplied for
 239 .Ar perm ,
 240 the ``\-'' operation has no effect.
 241 If no value is supplied for
 242 .Ar who ,
 243 each permission bit specified in
 244 .Ar perm ,
 245 for which the corresponding bit in the file mode creation mask
 246 is clear, is cleared.
 247 Otherwise, the mode bits represented by the specified
 248 .Ar who
 249 and
 250 .Ar perm
 251 values are cleared.
 252 .It =
 253 The mode bits specified by the
 254 .Ar who
 255 value are cleared, or, if no who value is specified, the owner, group
 256 and other mode bits are cleared.
 257 Then, if no value is supplied for
 258 .Ar who ,
 259 each permission bit specified in
 260 .Ar perm ,
 261 for which the corresponding bit in the file mode creation mask
 262 is clear, is set.
 263 Otherwise, the mode bits represented by the specified
 264 .Ar who
 265 and
 266 .Ar perm
 267 values are set.
 268 .El
 269 .Pp
 270 Each
 271 .Ar clause
 272 specifies one or more operations to be performed on the mode
 273 bits, and each operation is applied to the mode bits in the
 274 order specified.
 275 .Pp
 276 Operations upon the other permissions only (specified by the symbol
 277 ``o'' by itself), in combination with the
 278 .Ar perm
 279 symbols ``s'' or ``t'', are ignored.
 280 .Sh EXAMPLES
 281 .Bl -tag -width "u=rwx,go=u-w" -compact
 282 .It Li 644
 283 make a file readable by anyone and writable by the owner only.
 284 .Pp
 285 .It Li go-w
 286 deny write permission to group and others.
 287 .Pp
 288 .It Li =rw,+X
 289 set the read and write permissions to the usual defaults, but
 290 retain any execute permissions that are currently set.
 291 .Pp
 292 .It Li +X
 293 make a directory or file searchable/executable by everyone if it is
 294 already searchable/executable by anyone.
 295 .Pp
 296 .It Li 755
 297 .It Li u=rwx,go=rx
 298 .It Li u=rwx,go=u-w
 299 make a file readable/executable by everyone and writable by the owner only.
 300 .Pp
 301 .It Li go=
 302 clear all mode bits for group and others.
 303 .Pp
 304 .It Li g=u-w
 305 set the group bits equal to the user bits, but clear the group write bit.
 306 .El
 307 .Sh BUGS
 308 There's no
 309 .Ar perm
 310 option for the naughty bits.
 311 .Sh COMPATIBILITY
 312 The
 313 .Fl v
 314 option is non-standard and its use in scripts is not recommended.
 315 .Sh SEE ALSO
 316 .Xr chflags 1 ,
 317 .Xr install 1 ,
 318 .Xr chmod 2 ,
 319 .Xr stat 2 ,
 320 .Xr umask 2 ,
 321 .Xr fts 3 ,
 322 .Xr setmode 3 ,
 323 .Xr symlink 7 ,
 324 .Xr chown 8 ,
 325 .Xr mount 8 ,
 326 .Xr sticky 8
 327 .Sh STANDARDS
 328 The
 329 .Nm
 330 utility is expected to be
 331 .St -p1003.2
 332 compatible with the exception of the
 333 .Ar perm
 334 symbol
 335 .Dq t
 336 which is not included in that standard.
 337 .Sh HISTORY
 338 A
 339 .Nm
 340 command appeared in
 341 .At v1 .