File::Util - Easy, versatile, portable file handling


version 4.201720


File::Util provides a comprehensive toolbox of utilities to automate all kinds of common tasks on files and directories. Its purpose is to do so in the most portable manner possible so that users of this module won't have to worry about whether their programs will work on other operating systems and/or architectures. It works on Linux, Windows, Mac, BSD, Unix and others.

File::Util is written purely in Perl, and requires no compiler or make utility on your system in order to install and run it. It loads a minimal amount of code when used, only pulling in support for lesser-used methods on demand. It has no dependencies other than what comes installed with Perl itself.

File::Util also aims to be as backward compatible as possible, running without problems on Perl installations as old as 5.006. You are encouraged to run File::Util on Perl version 5.8 and above.

After browsing this document, please have a look at the other documentation. (See DOCUMENTATION section below.)


   # use File::Util in your program
   use File::Util;

   # create a new File::Util object
   my $f = File::Util->new();

   # read file into a variable
   my $content = $f->load_file( 'some_file.txt' );

   # write content to a file
   $f->write_file( 'some_other_file.txt' => 'Hello world!' );

   # get the contents of a directory, 3 levels deep
   my @songs = $f->list_dir( '~/Music' => { recurse => 1, max_depth => 3 } );


You can do much more with File::Util than the examples above. For an explanation of all the features available to you, take a look at these other reference materials:


The File::Util::Manual::Examples document has a long list of small, reusable code snippets and techniques to use in your own programs. This is the "cheat sheet", and is a great place to get started quickly. Almost everything you need is here.

Complete API Reference

The File::Util::Manual is the complete reference document explaining every available feature and object method. Use this to look up the full information on any given feature when the examples aren't enough.


The File::Util::Cookbook contains examples of complete, working programs that use File::Util to easily accomplish tasks which require file handling.


Getting Started

   # use File::Util in your program
   use File::Util;

   # can optionally enable File::Util's diagnostic error messages:
   # (see File::Util::Manual section regarding diagnostics)
   use File::Util qw( :diag );

   # create a new File::Util object
   my $f = File::Util->new();

   # can enable diagnostics for individual objects:
   $f = File::Util->new( diag => 1 );

File Operations

   # load file content into a scalar variable as raw text
   my $content = $f->load_file( 'somefile.txt' );

   # read a binary file the same way
   my $binary_content = $f->load_file( 'barking-cat.mp4' );

   # write a raw text file
   $f->write_file( 'somefile.txt' => $content );

   # ...and write a binary file, using some other options as well
      'llama.jpg' => $picture_data => { binmode => 1, bitmask => oct 644 }

   # ...or write a file with UTF-8 encoding (unicode support)
   $f->write_file( 'encoded.txt' => qq(\x{c0}) => { binmode => 'utf8' } );

   # load a file into an array, line by line
   my @lines = $f->load_file( 'file.txt' => { as_lines => 1 } );

   # see if you have permission to write to a file, then append to it
   if ( $f->is_writable( 'captains.log' ) ) {

      my $fh = $f->open_handle( 'captains.log' => 'append' );

      print $fh "Captain's log, stardate 41153.7.  Our destination is...";

      close $fh or die $!;
   else { # ...or warn the crew

      warn "Trouble on the bridge, the Captain can't access his log!";

   # get the number of lines in a file
   my $log_line_count = $f->line_count( '/var/log/messages' );

File Handles

   # get an open file handle for reading
   my $fh = $f->open_handle( 'Ian likes cats.txt' => 'read' );

   while ( my $line = <$fh> ) { # read the file, line by line
      # ... do stuff

   # get an open file handle for writing the same way
   $fh = $f->open_handle( 'John prefers dachshunds.txt' => 'write' );

   # You add the option to turn on UTF-8 strict encoding for your reads/writes
   $fh = $f->open_handle(
      'John prefers dachshunds.txt' => 'write' => { binmode => 'utf8' }

   print $fh "Bob is happy! \N{U+263A}"; # << unicode smiley face!

   # you can use sysopen to get low-level with your file handles if needed
   $fh = $f->open_handle(
      'alderaan.txt' => 'rwclobber' => { use_sysopen => 1 }

   syswrite $fh, "that's no moon";

   # ...You can use any of these syswrite modes with open_handle():
   # read, write, append, rwcreate, rwclobber, rwappend, rwupdate, and trunc

PLEASE NOTE that as of Perl 5.23, it is deprecated to mix system IO (sysopen/syswrite/sysread/sysseek) with utf8 binmode (see perldoc perlport). As such, File::Util will no longer allow you to do this after version 4.132140. Please see notes on UTF-8 and encoding further below.

      'somefile.txt' => 'write' => { use_sysopen => 1, binmode => 'utf8' }


   # get a listing of files, recursively, skipping directories
   my @files = $f->list_dir( '/var/tmp' => { files_only => 1, recurse => 1 } );

   # get a listing of text files, recursively
   my @textfiles = $f->list_dir(
      '/var/tmp' => {
         files_match => qr/\.txt$/,
         files_only  => 1,
         recurse     => 1,

   # walk a directory, using an anonymous function or function ref as a callback
   $f->list_dir( '/home/larry' => {
      recurse  => 1,
      callback => sub {
         my ( $selfdir, $subdirs, $files ) = @_;
         # do stuff ...
   } );

   # get an entire directory tree as a hierarchal datastructure reference
   my $tree = $f->list_dir( '/my/podcasts' => { as_tree => 1 } );

Getting Information About Files

   print 'My file has a bitmask of ' . $f->bitmask( 'my.file' );

   print 'My file is a ' . join(', ', $f->file_type( 'my.file' )) . " file.";

   warn 'This file is binary!' if $f->is_bin( 'my.file' );

   print 'My file was last modified on ' .
      scalar localtime $f->last_modified( 'my.file' );

Getting Information About Your System's IO Capabilities

   # Does your running Perl support unicode?
   print 'I support unicode' if $f->can_utf8;

   # Can your system use file locking?
   print 'I can use flock' if $f->can_flock;

   # The correct directory separator for your system
   print 'The correct directory separator for this system is ' . $f->SL;

   # Does your platform require binmode for all IO?
   print 'I always need binmode' if $f->needs_binmode;

   # Is your system an EBCDIC platform?  (see perldoc perlebcdic)
   print 'This is an EBCDIC platform, so be careful!' if $f->EBCDIC;

...See the File::Util::Manual for more details and features like advanced pattern matching in directories, callbacks, directory walking, user-definable error handlers, and more.

File Encoding and UTF-8

If you want to read/write in UTF-8, you can do that:

   $ftl->load_file( 'file.txt' => $content => { binmode => 'utf8' } );

   $ftl->write_file( 'file.txt' => $content => { binmode => 'utf8' } );

   $ftl->open_handle( 'file.txt' => 'read' => { binmode => 'utf8' } );

   # ...and so on

Only use binmode => 'utf8' for text.

Encoding and IO layers (sometimes called disciplines) can become complex. It's not something you usually need to worry about unless you wish to really fine tune File::Util's behavior beyond what are very suitable, portable defaults, or accomplish very specific tasks like encoding conversions.

You're free to specify any binmode you like, or allow File::Util to use the system's default IO layering. It will automatically use the ":raw" pseudo layer when reading files that are binary, unless specifically told to use something different.

You can control things as shown in the examples below:

   $ftl->load_file( 'file.txt' => $content => { binmode => SPEC } );

   $ftl->write_file( 'file.txt' => $content => { binmode => SPEC } );

   $ftl->open_handle( 'file.txt' => 'read' => { binmode => SPEC } );

...where SPEC is one or more of any supported IO layers on your system. Examples might include:

  • ':raw'

  • ':unix'

  • ':crlf'

  • ':stdio'

  • ':encoding(ENCODING)' with ENCODING's like iso-8859-1, shiftjis, etc

  • ...and much more

You can learn about the IO layers available to you and what they do in the PerlIO perldoc. Available options have increased over the years, and are likely subject to continued evolution. Consult the PerlIO and Encode documentation as your authoritative source of info on what layers to use.


File::Util consists of a set of smaller modules, but only loads the ones it needs when it needs them. It offers a comparatively fast load-up time, so using File::Util doesn't bloat your code's resource footprint.

Additionally, File::Util has been optimized to run fast. In many scenarios it does more and still out-performs other popular IO modules. Benchmarking tools are included as part of the File::Util installation package.

(See the benchmarking and profiling scripts that are included as part of this distribution.)


File::Util exposes the following public methods.

Each of which are covered in the File::Util::Manual, which has more room for the detailed explanation that is provided there.

This is just an itemized table of contents for HTML POD readers. For those viewing this document in a text terminal, open perldoc to the File::Util::Manual.

atomize_path (see atomize_path)
bitmask (see bitmask)
can_flock (see can_flock)
can_utf8 (see can_utf8)
created (see created)
default_path (see default_path)
diagnostic (see diagnostic)
ebcdic (see ebcdic)
escape_filename (see escape_filename)
existent (see existent)
file_type (see file_type)
flock_rules (see flock_rules)
is_bin (see is_bin)
is_readable (see is_readable)
is_writable (see is_writable)
last_access (see last_access)
last_changed (see last_changed)
last_modified (see last_modified)
line_count (see line_count)
list_dir (see list_dir)
load_dir (see load_dir)
load_file (see load_file)
make_dir (see make_dir)
abort_depth (see abort_depth)
needs_binmode (see needs_binmode)
new (see new)
onfail (see onfail)
open_handle (see open_handle)
read_limit (see read_limit)
return_path (see return_path)
size (see size)
split_path (see split_path)
strict_path (see strict_path)
strip_path (see strip_path)
touch (see touch)
trunc (see trunc)
unlock_open_handle (see unlock_open_handle)
use_flock (see use_flock)
valid_filename (see valid_filename)
write_file (see write_file)


Exports nothing by default. File::Util fully respects your namespace. You can, however, ask it for certain things (below).


The following symbols comprise @File::Util::EXPORT_OK, and as such are available for import to your namespace only upon request. They can be used either as object methods or like regular subroutines in your program.

   -  atomize_path      -  can_flock         -  can_utf8
   -  created           -  default_path      -  diagnostic
   -  ebcdic            -  escape_filename   -  existent
   -  file_type         -  is_bin            -  is_readable
   -  is_writable       -  last_access       -  last_changed
   -  last_modified     -  needs_binmode     -  strict_path
   -  return_path       -  size              -  split_path
   -  strip_path        -  valid_filename    -  NL and S L

To get any of these functions/symbols into your namespace without having to use them as object methods, use this kind of syntax:

   use File::Util qw( strip_path return_path existent size );

   my $file  = $ARGV[0];
   my $fname = strip_path( $file );
   my $path  = return_path( $file );
   my $size  = size( $file );

   print qq(File "$fname" exists in "$path", and is $size bytes in size)
      if existent( $file );


   :all (imports all of @File::Util::EXPORT_OK to your namespace)

   :diag (imports nothing to your namespace, it just enables diagnostics)

You can use these tags alone, or in combination with other symbols as shown above.


None. There are no external prerequisite modules.

File::Util only depends on modules that are part of the Core Perl distribution, and you don't need a compiler on your system to install it.

File::Util recommends Perl 5.8.1 or better ...

You can technically run File::Util on older versions of Perl 5, but it isn't recommended, especially if you want unicode support and wish to take advantage of File::Util's ability to read and write files using UTF-8 encoding.

Unicode::UTF8 is also recommended and helps speed things up in several places where you might choose to use unicode as described elsewhere in the File::Util::Manual.


To install this module type the following at the command prompt:

   perl Build.PL
   perl Build
   perl Build test
   sudo perl Build install

On Windows systems, the "sudo" part of the command may be omitted, but you will need to run the rest of the install command with Administrative privileges


Send bug reports and patches to the CPAN Bug Tracker for File::Util at


If you want to get help, contact the authors (links below in AUTHORS section)

I fully endorse as an excellent source of help with Perl in general.


The project website for File::Util is at

The git repository for File::Util is on Github at

Clone it at git://

This project was a private endeavor for too long so don't hesitate to pitch in.


The following people have contributed to File::Util in the form of feedback, encouragement, recommendations, testing, or assistance with problems either on or offline in one form or another. Listed in no particular order:

  • John Fields <>

  • BrowserUk <>

  • Ricardo SIGNES <>

  • Matt S Trout <>

  • Nicholas Perez <>

  • David Golden <>


Tommy Butler

Others Welcome!


Copyright(C) 2001-2013, Tommy Butler. All rights reserved.


This library is free software, you may redistribute it and/or modify it under the same terms as Perl itself. For more details, see the full text of the LICENSE file that is included in this distribution.


This software is distributed in the hope that it will be useful, but without any warranty; without even the implied warranty of merchantability or fitness for a particular purpose.

This disclaimer applies to every part of the File::Util distribution.


The rest of the documentation: File::Util::Manual, File::Util::Manual::Examples, File::Util::Cookbook

Other Useful Modules that do similar things: File::Slurp, File::Spec, File::Find::Rule, Path::Class, Path::Tiny