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35 .\" @(#)chmod.1 8.4 (Berkeley) 3/31/94
36 .\" $Id: chmod.1,v 1.10 1998/05/19 06:24:50 jkoshy Exp $
48 .Op Fl H | Fl L | Fl P
55 utility modifies the file mode bits of the listed files
60 The options are as follows:
65 option is specified, symbolic links on the command line are followed.
66 (Symbolic links encountered in the tree traversal are not followed.)
70 option is specified, all symbolic links are followed.
74 option is specified, no symbolic links are followed.
76 Change the modes of the file hierarchies rooted in the files
77 instead of just the files themselves.
80 Symbolic links do not have modes, so unless the
86 on a symbolic link always succeeds and has no effect.
92 options are ignored unless the
95 In addition, these options override each other and the
96 command's actions are determined by the last one specified.
98 Only the owner of a file or the super-user is permitted to change
103 utility exits 0 on success, and >0 if an error occurs.
105 Modes may be absolute or symbolic.
106 An absolute mode is an octal number constructed from the sum of
107 one or more of the following values:
109 .Bl -tag -width 6n -compact -offset indent
111 (the set-user-ID-on-execution bit) Executable files with this bit set
112 will run with effective uid set to the uid of the file owner.
113 Directories with the set-user-id bit set will force all files and
114 sub-directories created in them to be owned by the directory owner
115 and not by the uid of the creating process, if the underlying file
116 system supports this feature: see
123 (the set-group-ID-on-execution bit) Executable files with this bit set
124 will run with effective gid set to the gid of the file owner.
127 When set on a directory, unprivileged users can delete and rename
128 only those files in the directory that are owned by them, regardless of
129 the permissions on the directory. Under FreeBSD, the sticky bit is
130 ignored for executable files and may only be set for directories (see
135 Allow write by owner.
137 For files, allow execution by owner. For directories, allow the owner to
138 search in the directory.
140 Allow read by group members.
142 Allow write by group members.
144 For files, allow execution by group members. For directories, allow
145 group members to search in the directory.
147 Allow read by others.
149 Allow write by others.
151 For files, allow execution by others. For directories allow others to
152 search in the directory.
155 For example, the absolute mode that permits read, write and execute by
156 the owner, read and execute by group members, read and execute by
157 others, and no set-uid or set-gid behaviour is 755
158 (400+200+100+040+010+004+001).
160 The symbolic mode is described by the following grammar:
161 .Bd -literal -offset indent
162 mode ::= clause [, clause ...]
163 clause ::= [who ...] [action ...] last_action
164 action ::= op [perm ...]
165 last_action ::= op [perm ...]
166 who ::= a | u | g | o
168 perm ::= r | s | t | w | x | X | u | g | o
173 symbols ``u'', ``g'', and ``o'' specify the user, group, and other parts
174 of the mode bits, respectively.
177 symbol ``a'' is equivalent to ``ugo''.
182 symbols represent the portions of the mode bits as follows:
184 .Bl -tag -width Ds -compact -offset indent
188 The set-user-ID-on-execution and set-group-ID-on-execution bits.
194 The execute/search bits.
196 The execute/search bits if the file is a directory or any of the
197 execute/search bits are set in the original (unmodified) mode.
200 symbol ``X'' are only meaningful in conjunction with the
202 symbol ``+'', and are ignored in all other cases.
204 The user permission bits in the mode of the original file.
206 The group permission bits in the mode of the original file.
208 The other permission bits in the mode of the original file.
213 symbols represent the operation performed, as follows:
216 If no value is supplied for
218 the ``+'' operation has no effect.
219 If no value is supplied for
221 each permission bit specified in
223 for which the corresponding bit in the file mode creation mask
225 Otherwise, the mode bits represented by the specified
231 If no value is supplied for
233 the ``\-'' operation has no effect.
234 If no value is supplied for
236 each permission bit specified in
238 for which the corresponding bit in the file mode creation mask
239 is clear, is cleared.
240 Otherwise, the mode bits represented by the specified
246 The mode bits specified by the
248 value are cleared, or, if no who value is specified, the owner, group
249 and other mode bits are cleared.
250 Then, if no value is supplied for
252 each permission bit specified in
254 for which the corresponding bit in the file mode creation mask
256 Otherwise, the mode bits represented by the specified
265 specifies one or more operations to be performed on the mode
266 bits, and each operation is applied to the mode bits in the
269 Operations upon the other permissions only (specified by the symbol
270 ``o'' by itself), in combination with the
272 symbols ``s'' or ``t'', are ignored.
274 .Bl -tag -width "u=rwx,go=u-w" -compact
276 make a file readable by anyone and writable by the owner only.
279 deny write permission to group and others.
282 set the read and write permissions to the usual defaults, but
283 retain any execute permissions that are currently set.
286 make a directory or file searchable/executable by everyone if it is
287 already searchable/executable by anyone.
292 make a file readable/executable by everyone and writable by the owner only.
295 clear all mode bits for group and others.
298 set the group bits equal to the user bits, but clear the group write bit.
303 option for the naughty bits.
319 utility is expected to be
321 compatible with the exception of the
327 which are not included in that standard.