coreutils/doc/perm.texi

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13 access that users have to that file.  They can be represented either in
28 which control ordinary access to the file, and @dfn{special mode
36 permission to read the file.  For directories, this means permission to
40 permission to write to (change) the file.  For directories, this means
41 permission to create and remove files in the directory.
44 permission to execute the file (run it as a program).  For directories,
45 this means permission to access files in the directory.
49 to perform any of the above operations on a file:
69 In addition to the three sets of three permissions listed above, the
77 On execution, set the process's effective user ID to that of the file.
85 On execution, set the process's effective group ID to that of the file.
104 In addition to the file mode bits listed above, there may be file attributes
105 specific to the file system, e.g., access control lists (ACLs), whether a
108 specific to the file system.  For example:
113 On GNU and GNU/Linux the file attributes specific to
117 On FreeBSD the file flags specific to the FFS
140 @dfn{Symbolic modes} represent changes to files' mode bits as
141 operations on single-character symbols.  They allow you to modify either
172 removing, and setting the permission that certain users have to read,
184 The @var{users} part tells which users' access to the file is changed.
204 The @var{operation} part tells how to change the affected users' access
205 to the file, and is one of the following symbols:
210 to add the @var{permissions} to whatever permissions the @var{users}
215 to remove the @var{permissions} from whatever permissions the
219 to make the @var{permissions} the only permissions that the @var{users}
223 The @var{permissions} part tells what kind of access to the file should
228 at all to the file.
233 the permission the @var{users} have to read the file;
236 the permission the @var{users} have to write to the file;
239 the permission the @var{users} have to execute the file,
243 For example, to give everyone permission to read and write a regular file,
244 but not to execute it, use:
259 the file has to it, nor does it affect whether other users can
262 To give everyone except a file's owner no permission to do anything with
271 Another way to specify the same thing is:
293 adds the permissions for users who are in a file's group to the
296 it to mode 666 (@samp{rw-rw-rw-}).  If the file had started out as mode
297 741 (@samp{rwxr----x}), the above mode would change it to mode 745
305 In addition to changing a file's read, write, and execute/search permissions,
309 To change the file mode bits to set the user ID on execution, use
313 To change the file mode bits to set the group ID on execution, use
321 To change the file mode bits to set the restricted deletion flag or sticky bit,
325 For example, to set the set-user-ID mode bit of a program,
380 gives all users permission to search directories, or to execute files if
386 @cindex multiple changes to permissions
388 above (@pxref{Setting Permissions}).  It provides two ways to make
389 multiple changes to files' mode bits.
391 The first way is to specify multiple @var{operation} and
403 to it, gives them execute/search permission; and it also denies them write
404 permission to the file.  It does not affect the permission that the
405 owner of the file has for it.  The above mode is equivalent to
413 The second way to make multiple changes is to specify more than one
421 gives everyone permission to read the file and removes write
440 gives all users permission to read the file, and gives users who are in
441 the file's group permission to execute/search it as well, but not permission
442 to write to it.  The above mode could be written in several different
454 If the @var{users} part of a symbolic mode is omitted, it defaults to
458 @code{umask} command.  Its default value varies from system to system.
463 it allows you to use @code{umask} as an easily customizable protection
464 against giving away more permission to files than you intended to.
474 adds permission to write to the file to its owner and to other users who
475 are in the file's group, but @emph{not} to other users.  In contrast,
484 the file to all users.
493 alternative to giving a symbolic mode, you can give an octal (base 8)
496 The permissions granted to the user,
497 to other users in the file's group,
498 and to other users not in the file's group each require three
532 For example, numeric mode @samp{4751} corresponds to symbolic mode
533 @samp{u=srwx,g=rx,o=x}, and numeric mode @samp{664} corresponds to symbolic mode
534 @samp{ug=rw,o=r}.  Numeric mode @samp{0} corresponds to symbolic mode
541 to this general limitation.  @xref{Directory Setuid and Setgid}.
545 Numeric modes are always interpreted in octal; you do not have to add a
579 more easily, by lessening the need to use @command{chmod} or
580 @command{chown} to share new files.
585 mechanisms would be less convenient and it would be harder to share
607 If you want to try to set these bits, you must mention them
611 # These commands try to set the set-user-ID
622 If you want to try to clear these bits, you must mention them
627 # These commands try to clear the set-user-ID
636 not rely on requests to set or clear these bits on directories, as
637 POSIX allows implementations to ignore these requests.
639 is intended for scripts portable to systems that preserve these bits;
641 portable to systems that do not preserve the bits.