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32 .\" @(#)chmod.1 8.4 (Berkeley) 3/31/94
44 .Op Fl R Op Fl H | L | P
50 utility modifies the file mode bits of the listed files
55 The options are as follows:
56 .Bl -tag -width indent
58 Do not display a diagnostic message if
60 could not modify the mode for
62 nor modify the exit status to reflect such failures.
66 option is specified, symbolic links on the command line are followed.
67 (Symbolic links encountered in the tree traversal are not followed by
70 If the file is a symbolic link, change the mode of the link itself
71 rather than the file that the link points to.
75 option is specified, all symbolic links are followed.
79 option is specified, no symbolic links are followed.
82 Change the modes of the file hierarchies rooted in the files
83 instead of just the files themselves.
87 to be verbose, showing filenames as the mode is modified.
90 flag is specified more than once, the old and new modes of the file
91 will also be printed, in both octal and symbolic notation.
99 options are ignored unless the
102 In addition, these options override each other and the
103 command's actions are determined by the last one specified.
105 Only the owner of a file or the super-user is permitted to change
110 Modes may be absolute or symbolic.
111 An absolute mode is an octal number constructed from the sum of
112 one or more of the following values:
114 .Bl -tag -width 6n -compact -offset indent
117 Executable files with this bit set
118 will run with effective uid set to the uid of the file owner.
119 Directories with this bit set will force all files and
120 sub-directories created in them to be owned by the directory owner
121 and not by the uid of the creating process, if the underlying file
122 system supports this feature: see
130 Executable files with this bit set
131 will run with effective gid set to the gid of the file owner.
141 Allow write by owner.
143 For files, allow execution by owner.
144 For directories, allow the owner to
145 search in the directory.
147 Allow read by group members.
149 Allow write by group members.
151 For files, allow execution by group members.
152 For directories, allow
153 group members to search in the directory.
155 Allow read by others.
157 Allow write by others.
159 For files, allow execution by others.
160 For directories allow others to
161 search in the directory.
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).
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
176 perm ::= r | s | t | w | x | X | u | g | o
181 symbols ``u'', ``g'', and ``o'' specify the user, group, and other parts
182 of the mode bits, respectively.
185 symbol ``a'' is equivalent to ``ugo''.
189 symbols represent the portions of the mode bits as follows:
191 .Bl -tag -width Ds -compact -offset indent
195 The set-user-ID-on-execution and set-group-ID-on-execution bits.
201 The execute/search bits.
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.
207 symbol ``X'' are only meaningful in conjunction with the
209 symbol ``+'', and are ignored in all other cases.
211 The user permission bits in the original mode of the file.
213 The group permission bits in the original mode of the file.
215 The other permission bits in the original mode of the file.
220 symbols represent the operation performed, as follows:
223 If no value is supplied for
225 the ``+'' operation has no effect.
226 If no value is supplied for
228 each permission bit specified in
230 for which the corresponding bit in the file mode creation mask
234 Otherwise, the mode bits represented by the specified
240 If no value is supplied for
242 the ``\-'' operation has no effect.
243 If no value is supplied for
245 each permission bit specified in
247 for which the corresponding bit in the file mode creation mask
248 is clear, is cleared.
249 Otherwise, the mode bits represented by the specified
255 The mode bits specified by the
257 value are cleared, or, if no
259 value is specified, the owner, group
260 and other mode bits are cleared.
261 Then, if no value is supplied for
263 each permission bit specified in
265 for which the corresponding bit in the file mode creation mask
267 Otherwise, the mode bits represented by the specified
276 specifies one or more operations to be performed on the mode
277 bits, and each operation is applied to the mode bits in the
280 Operations upon the other permissions only (specified by the symbol
281 ``o'' by itself), in combination with the
283 symbols ``s'' or ``t'', are ignored.
285 The ``w'' permission on directories will permit file creation, relocation,
286 and copy into that directory.
287 Files created within the directory itself will inherit its group ID.
289 .Bl -tag -width "u=rwx,go=u-w" -compact
291 make a file readable by anyone and writable by the owner only.
294 deny write permission to group and others.
297 set the read and write permissions to the usual defaults, but
298 retain any execute permissions that are currently set.
301 make a directory or file searchable/executable by everyone if it is
302 already searchable/executable by anyone.
307 make a file readable/executable by everyone and writable by the owner only.
310 clear all mode bits for group and others.
313 set the group bits equal to the user bits, but clear the group write bit.
318 option is non-standard and its use in scripts is not recommended.
335 utility is expected to be
337 compatible with the exception of the
341 which is not included in that standard.
350 option for the naughty bits of a horse.