chmod [options]mode files

Change the access mode of one or more files. Only the owner of a file or a privileged user may change its mode. Create mode by concatenating the characters from who, opcode, and permission. who is optional (if omitted, default is a); choose only one opcode.

Common Options

-f, --quiet, --silent

Do not print error messages about files that cannot be changed.

-R, --recursive

Recursively descend through the directory, including subdirectories and symbolic links, setting the specified group ID as it proceeds. The last of -H, -L, and -P takes effect when used with -R.

GNU/Linux and Mac OS X Option

-v, --verbose

Verbosely describe ownership changes.

GNU/Linux Options

-c, --changes

Print information about files that are changed.


Do not treat the root directory, /, specially (the default).


Do not operate recursively on /, the root directory.

--reference= filename

Change the group to that associated with filename. In this case, newgroup is not specified.

Mac OS X Options

+a, +a#, -a, =a#

Parse, order, remove or rewrite ACL entries. See the chmod(1) manpage for more information.


Exit nonzero if any files have ACLs in noncanonical order.


Read new ACL information from standard input. If it parses correctly, use it to replace the existing ACL information.


When used with -R, if a command-line argument is a symbolic link to a directory, recursively traverse the directory.


Remove the “inherited” bit from all entries in ...

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