File::chmod - Implements symbolic and ls chmod modes


version 0.42


  use File::chmod;
  $File::chmod::UMASK = 0;
  # It is recommended that you explicitly set $File::chmod::UMASK
  # as the default will change in the future
  # 0 is recommended to behave like system chmod
  # 1 if you want File::chmod to apply your environment set umask.
  # 2 is how we detect that it's internally set, undef will become the
  # default in the future, eventually a lexicaly scoped API may be designed

  # chmod takes all three types
  # these all do the same thing

  # or

  use File::chmod qw( symchmod lschmod );

  chmod(0666,@files);           # this is the normal chmod
  symchmod("=rw",@files);       # takes symbolic modes only
  lschmod("-rw-rw-rw-",@files); # takes "ls" modes only

  # more functions, read on to understand


File::chmod is a utility that allows you to bypass system calls or bit processing of a file's permissions. It overloads the chmod() function with its own that gets an octal mode, a symbolic mode (see below), or an "ls" mode (see below). If you wish not to overload chmod(), you can export symchmod() and lschmod(), which take, respectively, a symbolic mode and an "ls" mode.

An added feature to version 0.30 is the $UMASK variable, explained in detail below; if symchmod() is called and this variable is true, then the function uses the (also new) $MASK variable (which defaults to umask()) as a mask against the new mode. This mode is on by default, and changes the behavior from what you would expect if you are used to UNIX chmod. This may change in the future.

Symbolic modes are thoroughly described in your chmod(1) man page, but here are a few examples.

  chmod("+x","file1","file2");  # overloaded chmod(), that is...
  # turns on the execute bit for all users on those two files

  # removes 'other' permissions, and the write bit for 'group'

  # sets all bits to those in 'user'

"ls" modes are the type produced on the left-hand side of an ls -l on a directory. Examples are:

  # the 0755 setting; user has read-write-execute, group and others
  # have read-execute priveleges

  # sets read-write-execute for user and group, none for others
  # also sets set-uid and set-gid bits

The regular chmod() and lschmod() are absolute; that is, they are not appending to or subtracting from the current file mode. They set it, regardless of what it had been before. symchmod() is useful for allowing the modifying of a file's permissions without having to run a system call or determining the file's permissions, and then combining that with whatever bits are appropriate. It also operates separately on each file.



Takes an octal, symbolic, or "ls" mode, and then chmods each file appropriately.


Returns a list of modified permissions, without chmodding files. Accepts any of the three kinds of modes.

  @newmodes = getchmod("+x","file1","file2");
  # @newmodes holds the octal permissions of the files'
  # modes, if they were to be sent through chmod("+x"...)



Takes a symbolic permissions mode, and chmods each file.


Takes an "ls" permissions mode, and chmods each file.


Returns a list of modified permissions, without chmodding files. Accepts only symbolic permission modes.


Returns a list of modified permissions, without chmodding files. Accepts only "ls" permission modes.


Returns a list of the current mode of each file.



If set to a true value, it will report warnings, similar to those produced by chmod() on your system. Otherwise, the functions will not report errors. Example: a file can not have file-locking and the set-gid bits on at the same time. If $File::chmod::DEBUG is true, the function will report an error. If not, you are not warned of the conflict. It is set to 1 as default.


Contains the umask to apply to new file modes when using getsymchmod(). This defaults to the return value of umask() at compile time. Is only applied if $UMASK is true.


This is a boolean which tells getsymchmod() whether or not to apply the umask found in $MASK. It defaults to true.


This is only good on Unix-like boxes. I would like people to help me work on File::chmod for any OS that deserves it. If you would like to help, please email me (address below) with the OS and any information you might have on how chmod() should work on it; if you don't have any specific information, but would still like to help, hey, that's good too. I have the following information (from "perlport"):


Only good for changing "owner" read-write access, "group", and "other" bits are meaningless. NOTE: Win32::File and Win32::FileSecurity already do this. I do not currently see a need to port File::chmod.


Only limited meaning. Disabling/enabling write permission is mapped to locking/unlocking the file.


Only good for changing "owner" and "other" read-write access.


  Stat::lsMode (by Mark-James Dominus, CPAN ID: MJD)
  chmod(1) manpage
  perldoc -f chmod
  perldoc -f stat


Please report any bugs or feature requests on the bugtracker website

When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature.


  • David Steinbrunner <>

  • Slaven Rezic <>

  • Steve Throckmorton <>

  • Tim <>


  • Jeff Pinyan <>

  • Caleb Cushing <>


This software is copyright (c) 2015 by Caleb Cushing and Jeff Pinyan.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.