Get the contents of a file in a string

   my $contents = $f->load_file( 'filename' );

      -OR-

   my $contents = $f->load_file( '/path/to/filename' );

      -OR-

   my $contents = $f->load_file( 'C:\path\to\filename' );

Get the contents of a UTF-8 encoded file in a UTF-8 encoded string

   my $encoded_data = $f->load_file( 'encoded.txt' => { binmode => 'utf8' } );

Get the contents of a file in an array of lines in the file

   my @contents = $f->load_file( 'filename' => { as_lines => 1 } );

Get an open file handle for reading

   my $fh = $f->open_handle(
      file => '/some/existing/file',
      mode => 'read'
   );

      -OR-

   # ... you can also use the shorter syntax:
   my $fh = $f->open_handle( '/some/existing/file' => 'read' );

   # ... you can open a file handle to a UTF-8 encoded file too
   my $fh = $f->open_handle( 'encoded.txt' => 'read' => { binmode => 'utf8' } );

   # then use the filehandle like you would use any other file handle:
   while ( my $line = <$fh> ) {

      # ... do stuff with $line
   }

   close $fh or die $!;

Get an open file handle for writing

   my $fh = $f->open_handle(
      file => '/some/file',
      mode => 'write'
   );

      -OR-

   # ... you can also use the shorter syntax:
   my $fh = $f->open_handle( '/some/file' => 'write' );

   # ... you can open a file handle with UTF-8 encoding support
   my $fh = $f->open_handle( '/some/file' => 'write' => { binmode => 'utf8' } );

   print $fh 'Hello world!';

   close $fh or die $!;

Write to a new or existing file

   my $content = 'Pathelogically Eclectic Rubbish Lister';

   $f->write_file( file => 'a new file.txt', content => $content );

      -OR-

   # you can use the shorter syntax:
   $f->write_file( 'a new file.txt' => $content );

      -OR-

   # write UTF-8 encoded data also.  the file will have UTF-8 encoding:
   $f->write_file( 'encoded.txt' => $encoded_data => { binmode => 'utf8' } );

You can optionally specify a bitmask for a file if it doesn't exist yet. The bitmask is combined with the user's current umask for the creation mode of the file. (You should usually omit this.)

   $f->write_file(
      file    => 'C:\some\new\file.txt',
      content => $content
      bitmask => oct 777,
   );

      -OR-

   $f->write_file( 'file.txt' => $content => { bitmask => oct 777 } );

Warn if the file couldn't be written, instead of dying by default

   $f->write_file(
      'file.txt' => $content,
      {
         onfail  => 'warn',
         bitmask => oct 777
      }
   );

Conceal the error if the file couldn't be written (secure), but log it too

   # define a custom (secure) error handler

   $f->write_file(
      'file.txt' => $content =>
      {
         bitmask => oct 777
         onfail  => sub {
            my ( $err, $stack ) = @_;

            # send the error message and stack trace to a logger of some kind...
            $logger->log( $err . $stack );

            # or send an email alert?
            send_email_alert_to_admin( $err ); #<< you'll have to write that sub

            # return undef to indicate a problem (or you could die/exit too)
            return;
         }
      }
   );

Why not first check if the file is writeable/can be created

   if ( $f->is_writable( '/root/some/file.txt' ) ) {

      # ... now create/write to the file
   }

Append to a new or existing file

   my $content = 'The fastest hunk of junk in the galaxy';

   $f->write_file(
      file    => 'mfalcon.spec',
      mode    => 'append',
      content => $content
   );

      -OR-

   $f->write_file( 'mfalcon.spec' => $content => { mode => 'append' } );

Get the names of all files and subdirectories in a directory

   # option no_fsdots excludes "." and ".." from the list
   my @dirs_and_files = $f->list_dir( '/foo' => { no_fsdots => 1 } );

Get the names of all files and subdirectories in a directory, recursively

   my @dirs_and_files = $f->list_dir( '/foo' => { recurse => 1 } );

Do the same as above, but only to a certain maximum depth

   my @dirs_and_files =
      $f->list_dir( '/foo' => { recurse => 1, max_depth => 3 } );

Do the same, but ignore potential filesystem loops for a speed boost

   my @dirs_and_files =
      $f->list_dir( '/foo' => { recurse_fast => 1, max_depth => 3 } );

Get the names of all files (no subdirectories) in a directory

   my @dirs_and_files = $f->list_dir( '/foo' => { files_only => } );

Get the names of all subdirectories (no files) in a directory

   my @dirs_and_files = $f->list_dir( '/foo' => { dirs_only => 1 } );

Get the number of files and subdirectories in a directory

   my @dirs_and_files = $f->list_dir(
      '/foo' => { no_fsdots => 1, count_only => 1 }
   );

Get the names of files and subdirs in a directory as separate array refs

   my( $dirs, $files ) = $f->list_dir( '/foo' => { as_ref => 1 } );

      -OR-

   my( $dirs, $files ) = $f->list_dir(
      '/foo' => { dirs_as_ref => 1, files_as_ref => 1 }
   );

Load all the files in a directory into a hashref

   my $templates = $f->load_dir( '/var/www/mysite/templates' );

   # $templates now contains something like:
   # {
   #    'header.html' => '...file contents...',
   #    'body.html'   => '...file contents...',
   #    'footer.html' => '...file contents...',
   # }

   print $templates->{'header.html'};

Recursively Get the names of all files that end in '.pl'

   my @perl_files = $f->list_dir(
      '/home/scripts' => { files_match => qr/\.pl$/, recurse => 1 }
   }

Recursively get the names of all files that do NOT end in '.pl'

It might sound complicated for a beginner, but it's really not that hard.

See the perlre documentation for more about negation in regular expressions.

   # find all files that don't end in ".pl"
   my @other_files = $f->list_dir(
      '/home/scripts' => { files_match => qr/^(?!.*\.pl$)/, recurse => 1 }
   }

Combine several options for list_dir() and be awesome

   # find the droids I'm looking for...
   my @files = $f->list_dir(
      '/home/anakin' => {
         files_match    => { or  => [ qr/droid/, qr/3p(o|O)$/i, qr/^R2/ },
         parent_matches => { and => [ qr/vader/i, qr/darth/i ] },
         path_matches   => { and => [ qr/obi-wan/i, qr/^(?!.*Qui-Gon)/ ] },
         recursive      => 1,
         files_only     => 1,
         max_depth      => 8,
      }
   );

The above example would find and return files like:

   /home/anakin/mentors/obi-wan/villains/darth-vader/R2.png
   /home/anakin/mentors/obi-wan/villains/darth-vader/C3P0.dict
   /home/anakin/mentors/obi-wan/villains/darth-vader/my_droids.list

But would not return files like:

   /home/anakin/mentors/Qui-Gon Jinn/villains/darth-vader/my_droids.list

Use a callback to descend through (walk) a directory tree

Any time you specify a callback, File::Util will make sure it's first argument is the name if the directory it's in (recursion), and then the second and third arguments are listrefs. The first is a list reference containing the names of all subdirectories, and the second list ref contains the names of all the files.

Below is a very simple example that doesn't really do much other than demonstrate the syntax. You can see more full-blown examples of callbacks in the File::Util::Cookbook

   # print all subdirectories under /home/larry/
   $f->list_dir(
      '/home/larry' => {
         callback => sub { print shift @_, "\n" },
         recurse  => 1,
      }
   }

Get a directory tree in a hierarchical hashref

   my $tree = $f->list_dir( '/tmp' => { as_tree => 1, recurse => 1 } );

   Gives you a datastructure like:
   {
     '/' => {
              '_DIR_PARENT_' => undef,
              '_DIR_SELF_' => '/',
              'tmp' => {
                         '_DIR_PARENT_' => '/',
                         '_DIR_SELF_' => '/tmp',
                         'hJMOsoGuEb' => {
                                           '_DIR_PARENT_' => '/tmp',
                                           '_DIR_SELF_' => '/tmp/hJMOsoGuEb',
                                           'a.txt' => '/tmp/hJMOsoGuEb/a.txt',
                                           'b.log' => '/tmp/hJMOsoGuEb/b.log',
                                           'c.ini' => '/tmp/hJMOsoGuEb/c.ini',
                                           'd.bat' => '/tmp/hJMOsoGuEb/d.bat',
                                           'e.sh' => '/tmp/hJMOsoGuEb/e.sh',
                                           'f.conf' => '/tmp/hJMOsoGuEb/f.conf',
                                           'g.bin' => '/tmp/hJMOsoGuEb/g.bin',
                                           'h.rc' => '/tmp/hJMOsoGuEb/h.rc',
                                         }
                       }
            }
   }

*You can add the "dirmeta" option, set to 0 (false), to remove the special entries "_DIR_PARENT_" and "_DIR_SELF_" from each subdirectory branch.

Example:

   my $tree = $f->list_dir(
      '/tmp' => { as_tree => 1, dirmeta => 0, recurse => 1 }
   );

*You can still combine the "as_tree" option with other options, such as the regex pattern matching options covered above, or options like "recurse", or "files_only".

*You should be careful using this feature with very large directory trees, due to the memory it might consume. Memory usage is generally low, but will grow when you use this feature for larger and larger directory trees. Bear in mind that the $ABORT_DEPTH limit applies here too (see File::Util documentation), which you can override manually by setting the "abort_depth" option:

   # set max recursion limit to an integer value as shown below
   $f->list_dir( '/tmp' => { as_tree => 1, recurse => 1, abort_depth => 123 } );

Determine if something is a valid file name

   print $f->valid_filename( 'foo?+/bar~@/#baz.txt' ) ? 'ok' : 'bad';

      -OR-

   print File::Util->valid_filename( 'foo?+/bar~@/#baz.txt' ) ? 'ok' : 'bad';

Like many other methods in File::Util, you can import this into your own namespace so you can call it like any other function, avoid the object-oriented syntax when you don't want or need it: (This manual doesn't duplicate the main documentation by telling you every method you can import -- see the @EXPORT_OK section of the File::Util documentation)

   use File::Util qw( valid_filename );

   if ( valid_filename( 'foo?+/bar~@/#baz.txt' ) )
   {
      print 'file name is valid';
   }
   else
   {
      print 'That file name contains illegal characters';
   }

Get the number of lines in a file

   my $linecount = $f->line_count( 'foo.txt' );

Split a file path into its parts

   use File::Util qw( split_path );

   print "$_\n" for split_path( q{C:\foo\bar\baz\flarp.pl} )

      -OR-

   print "$_\n" for $f->split_path( q{C:\foo\bar\baz\flarp.pl} )

      -OR-

   print "$_\n" for File::Util->split_path( q{C:\foo\bar\baz\flarp.pl} )

   The output of all of the above commands is:
      C:\
      foo
      bar
      baz
      flarp.pl

Above you see examples working on Windows-type paths. Below are some examples using *nix-style paths:

   print "$_\n" for split_path( '/I/am/your/father/NOOOO' )

   The output of all of the above commands is:
      /
      I
      am
      your
      father
      NOOOO

Strip the path from a file name

   # On Windows
   #  (prints "hosts")
   my $path = $f->strip_path( 'C:\WINDOWS\system32\drivers\etc\hosts' );

   # On Linux/Unix
   #  (prints "perl")
   print $f->strip_path( '/usr/bin/perl' );

   # On a Mac
   #  (prints "baz")
   print $f->strip_path( 'foo:bar:baz' );

      -OR-

   use File::Util qw( strip_path );

   print strip_path( '/some/file/name' ); # prints "name"

Get the path preceding a file name

   # On Windows
   #  (prints "C:\WINDOWS\system32\drivers\etc")
   my $path = $f->return_path( 'C:\WINDOWS\system32\drivers\etc\hosts' );

   # On Linux/Unix
   #  (prints "/usr/bin")
   print $f->return_path( '/usr/bin/perl' );

   # On a (very, very old) Mac
   #  (prints "foo:bar")
   print $f->return_path( 'foo:bar:baz' );

Find out if the host system can use flock

   use File::Util qw( can_flock );
   print can_flock;

      -OR-

   print File::Util->can_flock;

      -OR-

   print $f->can_flock;

Find out if the host system needs to call binmode on binary files

   use File::Util qw( needs_binmode );
   print needs_binmode;

      -OR-

   print File::Util->needs_binmode;

      -OR-

   print $f->needs_binmode;

Find out if a file can be opened for read (based on file permissions)

   my $is_readable = $f->is_readable( 'foo.txt' );

Find out if a file can be opened for write (based on file permissions)

   my $is_writable = $f->is_writable( 'foo.txt' );

Escape illegal characters in a potential file name (and its path)

   # prints "C__WINDOWS_system32_drivers_etc_hosts"
   print $f->escape_filename( 'C:\WINDOWS\system32\drivers\etc\hosts' );

   # prints "baz)__@^"
   # (strips the file path from the file name, then escapes it
   print $f->escape_filename( '/foo/bar/baz)?*@^' => { strip_path => 1 } );

   # prints "_foo_!_@so~me#illegal$_file&(name"
   # (yes, technically that is a legal filename)
   print $f->escape_filename( q{\foo*!_@so~me#illegal$*file&(name} );

Find out if the host system uses EBCDIC

   use File::Util qw( ebcdic );
   print ebcdic;

      -OR-

   print File::Util->ebcdic;

      -OR-

   print $f->ebcdic;

Get the type(s) of an existent file

   use File::Util qw( file_type );
   print file_type( 'foo.exe' );

      -OR-

   print File::Util->file_type( 'bar.txt' );

      -OR-

   print $f->file_type( '/dev/null' );

Get the bitmask of an existent file

   use File::Util qw( bitmask );
   print bitmask( '/usr/sbin/sendmail' );

      -OR-

   print File::Util->bitmask( 'C:\COMMAND.COM' );

      -OR-

   print $f->bitmask( '/dev/null' );

Get time of creation for a file

   use File::Util qw( created );
   print scalar localtime created( '/usr/bin/exim' );

      -OR-

   print scalar localtime File::Util->created( 'C:\COMMAND.COM' );

      -OR-

   print scalar localtime $f->created( '/bin/less' );

Get the last access time for a file

   use File::Util qw( last_access );
   print scalar localtime last_access( '/usr/bin/exim' );

      -OR-

   print scalar localtime File::Util->last_access( 'C:\COMMAND.COM' );

      -OR-

   print scalar localtime $f->last_access( '/bin/less' );

Get the inode change time for a file

   use File::Util qw( last_changed );
   print scalar localtime last_changed( '/usr/bin/vim' );

      -OR-

   print scalar localtime File::Util->last_changed( 'C:\COMMAND.COM' );

      -OR-

   print scalar localtime $f->last_changed( '/bin/cpio' );

Get the last modified time for a file

   use File::Util qw( last_modified );
   print scalar localtime last_modified( '/usr/bin/exim' );

      -OR-

   print scalar localtime File::Util->last_modified( 'C:\COMMAND.COM' );

      -OR-

   print scalar localtime $f->last_modified( '/bin/less' );

Make a new directory, recursively if necessary

   $f->make_dir( '/var/tmp/tempfiles/foo/bar/' );

   # you can optionally specify a bitmask for the new directory.
   # the bitmask is combined with the user's current umask for the creation
   # mode of the directory.  (You should usually omit this.)

   $f->make_dir( '/var/tmp/tempfiles/foo/bar/', 0755 );

Touch a file

   use File::Util qw( touch );
   touch( 'somefile.txt' );

      -OR-

   $f->touch( '/foo/bar/baz.tmp' );

Truncate a file

   $f->trunc( '/wibble/wombat/noot.tmp' );

Get the correct path separator for the host system

   use File::Util qw( SL );
   print SL;

      -OR-

   print File::Util->SL;

      -OR-

   print $f->SL;

Get the correct newline character for the host system

   use File::Util qw( NL );

   print NL;

      -OR-

   print File::Util->NL;

      -OR-

   print $f->NL;

Choose what to do if there's a problem (die, warn, zero, undefined, subref)

   # When doing things with IO that might fail, set up good error handlers

   # "Fail, these examples will..."

   # If this call fails, die with an error message (*default*)
   $f->write_file( 'bobafett.txt' => $content => { onfail => 'die' } );

   # If this call fails, issue a warning to STDERR, but don't die/exit
   $f->list_dir( '/home/greivous' => { onfail => 'warn' } );

   # If this call fails, return a zero value (0), and don't die/exit
   $f->open_handle( '/home/ventress/.emacs' => { onfail => 'zero' } );

   # If this call fails, return undef, and don't die/exit
   $f->load_file( '/home/vader/darkside.manual' => { onfail => 'undefined' } );

   # If this call fails, execute the subroutine code and do whatever it says
   # This code tries to load one directory, and failing that, loads another
   $f->load_dir( '/home/palpatine/lofty_plans/' => {
         onfail => sub { return $f->load_dir( '/home/sidious/evil_plots/' ) }
      }
   );