chmod Mac OS X Access Control List (ACL) features too _ _

Mac OS X
linux chmod

chmod -- change file modes or Access Control Lists (ACL)

chmod [-fv ] [-R [-H | -L | -P] mode file … chmod [-fv ] [-R [-H | -L | -P] [-a | +a | =a] ACE file … chmod [-fhv] [-R [-H | -L | -P] [-E] file … chmod [-fhv] [-R [-H | -L | -P] [-C] file … chmod [-fhv] [-R [-H | -L | -P] [-N] file …

Modifies the file mode bits and Access Control Lists (ACLs)

-f Do not display a message if modify fails for file.
-R Change the modes of the file hierarchies rooted in the files instead of just the files the
-H, -L and -P are ignored without -R , override each other and the results are the last specified.

•Symbolic link behavor ( with -R)
-H symbolic links on the command line are followed.
Symbolic links encountered in the tree traversal are not followed by default.
-L followed.
-P NOT followed.Default.

-h change the mode of the link itself rather than the target
-v verbose, showing filenames as the mode is modified.
Specified more than once, the old and new modes of the file will also be displayed, in both octal and symbolic notation.

Only the owner of a file or the super-user is permitted to change the mode of a file.

DIAGNOSTICS

The chmod utility exits 0 on success, and >0 if an error occurs.

MODES

Modes may be absolute or symbolic. An absolute mode is an octal number constructed from the sum of one or more of the following values:

`4000`	(the set-user-ID-on-execution bit) Executable files with this bit set will run with effective uid set to the uid of the file owner. Directories with the set-user-id bit set will force all files and sub-directories created in them to be owned by the directory owner and not by the uid of the creating process, if the underlying file system supports this feature: see chmod(2) and the suiddir option to mount(8).
`2000`	(the set-group-ID-on-execution bit) Executable files with this bit set will run with effective gid set to the gid of the file owner.
`1000`	(the sticky bit) See chmod(2) and sticky(8).
`0400`	Allow read by owner.
`0200`	Allow write by owner.
`0100`	For files, allow execution by owner. For directories, allow the owner to search in the directory.
`0040`	Allow read by group members.
`0020`	Allow write by group members.
`0010`	For files, allow execution by group members. For directories, allow group members to search in the directory.
`0004`	Allow read by others.
`0002`	Allow write by others.
`0001`	For files, allow execution by others. For directories allow others to search in the directory.

For example, the absolute mode that permits read, write and execute by the owner, read and execute by group members, read and execute by others, and no set-uid or set-gid behaviour is 755 (400+200+100+040+010+004+001). The symbolic mode is described by the following grammar:

           mode         ::= clause [, clause ...]
           clause       ::= [who ...] [action ...] action
           action       ::= op [perm ...]
           who          ::= a | u | g | o
           op           ::= + | - | =
           perm         ::= r | s | t | w | x | X | u | g | o

The who symbols u, g, and o specify the user, group, and other mode bits, a all is equivalent to ugo.

The perm symbols represent the portions of the mode (permission) bits:

           r       read bits.
           w       write bits.
           x       execute/search bits.

           s       set-user-ID-on-execution and set-group-ID-on-execution bits.
           t       sticky bit.
           X       execute/search bits if the file is a directory or any of the execute/search bits are
                   set in the original (unmodified) mode.  Operations with the perm symbol X are only
                   meaningful in conjunction with the op symbol +, and are ignored in all other cases.

           u       user permission bits
           g       group permission bits
           o       other permission bits

ls -l -rw------- 1 5595 Feb 22 12:31 .bash_history -rwxr----- 1 27 Dec 15 16:31 .profile

The op symbols represent the operation performed:

     +     If no value is supplied for perm, + has no effect.  
           If no value is supplied for who, each permission bit specified in perm, for which the corresponding bit in the file mode creation mask is clear, is set.  
           Otherwise, the mode bits represented by the specified who and perm values are set.

     -     If no value is supplied for who, each permission bit specified in perm, for which the corresponding bit in the file mode creation mask is clear, is cleared.  
           Otherwise, the mode bits represented by the specified who and perm values are cleared.

     =     The mode bits specified by the who value are cleared, or, if no who value is specified, the
           owner, group and other mode bits are cleared.  
           if no value is supplied for who, each permission bit specified in perm, for which the corresponding bit in the file mode creation mask is
           clear, is set.  
           Otherwise, the mode bits represented by the specified who and perm values are set.

Each clause specifies one or more operations to be performed on the mode bits, and each operation is applied to the mode bits in the order specified.

Operations upon the other permissions only (specified by the symbol o by itself), in combination with the perm symbols s or t, are ignored.

EXAMPLES OF VALID MODES

`644`	make a file readable by anyone and writable by the owner only.

`go-w`	deny write permission to group and others.
`=rw,+X`	set the read and write permissions to the usual defaults, but retain any execute permissions that are currently set.
`+X`	make a directory or file searchable/executable by everyone if it is already searchable/executable by anyone.
`755 u=rwx,go=rx u=rwx,go=u-w`	make a file readable/executable by everyone and writable by the owner only.
`go=`	clear all mode bits for group and others.
`g=u-w`	set the group bits equal to the user bits, but clear the group write bit.

COMPATIBILITY The -v option is non-standard and its use in scripts is not recommended.
SEE ALSO chflags(1), fsaclctl(1), install(1), chmod(2), stat(2), umask(2), fts(3), setmode(3), symlink(7), chown(8), mount(8), sticky(8)
STANDARDS The chmod utility is expected to be IEEE Std 1003.2 (`POSIX.2`) compatible with the exception of the `perm` symbol `t` which is not included in that standard.

DIAGNOSTICS

MODES

EXAMPLES OF VALID MODES

ACL MANIPULATION OPTIONS

SEE ALSO chflags(1), fsaclctl(1), install(1), chmod(2), stat(2), umask(2), fts(3), setmode(3), symlink(7), chown(8), mount(8), sticky(8)

STANDARDS The chmod utility is expected to be IEEE Std 1003.2 (POSIX.2) compatible with the exception of the perm symbol t which is not included in that standard.

STANDARDS The chmod utility is expected to be IEEE Std 1003.2 (`POSIX.2`) compatible with the exception of the `perm` symbol `t` which is not included in that standard.