File::Util::Cookbook(3)

NAME
File::Util::Cookbook - File::Util in Action

VERSION
version 4.201720

INTRODUCTION
The following are fully functional programs using File::Util to accomplish some common tasks. Note that not nearly everything helpful use of File::Util could be covered here, but the following are examples showing answers to the questions commonly asked.

For a simple reference on File::Util, take a look at the manual at File::Util::Manual.

EXAMPLES
These are included in the standalone scripts that come in the "examples" directory as part of this distribution.

  Batch File Rename
   # This code changes the file suffix of all files in a directory
   # ending in *.log so that they end in *.txt
   #
   # Note - This example is NOT recursive.

   use strict;
   use warnings;
   use vars qw( $dir );

   # Regarding "SL" below: On Win/DOS, it is "\" and on Mac/BSD/Linux it is "/"
   # File::Util will automatically detect this for you.
   use File::Util qw( NL SL );

   my $ftl   = File::Util->new();
   my $dir   = 'some/log/directory';
   my @files = $ftl->list_dir( $dir => { files_only => 1 } );

   foreach my $file ( @files ) {

      # don't change the file suffix unless it is *.log
      next unless $file =~ /log$/;

      my $newname = $file;
         $newname =~ s/\.log$/\.txt/;

      if ( rename $dir . SL . $file, $dir . SL . $newname ) {

         print qq($file -> $newname), NL
      }
      else {

         warn qq(Couldn't rename "$_" to "$newname" - $!)
      }
   }

   exit;

  Recursively remove a directory and all its contents
   # This code removes a directory and everything in it

   use strict;
   use warnings;
   use File::Util qw( NL );

   my $ftl = File::Util->new();
   my $removedir = '/path/to/directory/youwanttodelete';

   my @gonners = $ftl->list_dir( $removedir => { recurse => 1 } );

   # remove directory and everything in it
   @gonners = reverse sort { length $a <=> length $b } @gonners;

   foreach my $gonner ( @gonners, $removedir ) {

      print "Removing $gonner ...", NL;

      -d $gonner ? rmdir $gonner || die $! : unlink $gonner || die $!;
    }

   print 'Done!', NL;

   exit;

  Try opening a file, falling back to a failsafe file if there's an error
   use strict;
   use warnings;

   use File::Util qw( NL );

   my $ftl = File::Util->new();

   my $might_not_work     = '/this/might/not/work.txt';
   my $will_work_for_sure = '/tmp/file.txt';
   my $used_backup_plan   = 0;

   my $file_handle = $ftl->open_handle
   (
      $might_not_work =>
      {
         mode   => 'write',
         onfail => sub
         {
            my ( $err, $stack_trace ) = @_;

            warn "Couldn't open first choice, trying a backup plan...";

            $used_backup_plan = 1;

            return $ftl->open_handle
            (
               $will_work_for_sure => { mode => 'write' }
            );
         },
      }
   );

   print $file_handle 'Hello World!  The time is now ' . scalar localtime;

   print $file_handle NL; # portably add a new line to the end of the file

   close $file_handle or die $!;

   # print out whichever file we were able to successfully write
   print $ftl->load_file
   (
      $used_backup_plan
         ? $will_work_for_sure
         : $might_not_work
   );

   exit;

  Wrap the lines in a file at 72 columns, then save it
   # This code opens a file, wraps its lines, and saves the file with
   # the newly formatted content

   use strict; # always
   use warnings;

   use File::Util qw( NL );
   use Text::Wrap qw( wrap );

   $Text::Wrap::columns = 72; # wrap text at this many columns

   my $f = File::Util->new();
   my $textfile = 'myreport.txt'; # file to wrap and save

   $f->write_file(
     filename => $textfile,
     content => wrap('', '', $f->load_file($textfile))
   );

   print 'Done.', NL x 2;

  Read and increment a counter file, then save it
   # This code opens a file, reads a number value, increments it,
   # then saves the newly incremented value back to the file

   # For the sake of simplicity, this code assumes:
   #   * the counter file already exist and is writeable
   #   * the counter file has one line, which contains only numbers

   use strict; # always
   use warnings;

   use File::Util;

   my $ftl = File::Util->new();
   my $counterfile = 'counter.txt'; # the counter file needs to already exist

   my $count = $ftl->load_file( $counterfile );

   # convert textual number to in-memory int type, -this will default
   # to a zero if it encounters non-numerical or empty content
   chomp $count;
   $count = int $count;

   print "Count value from file: $count.";

   $count++; # increment the counter value by 1

   # save the incremented count back to the counter file
   $ftl->write_file( filename => $counterfile, content => $count );

   # verify that it worked
   print ' Count is now: ' . $ftl->load_file( $counterfile );

   exit;

  Batch Search & Replace
   # Code does a recursive batch search/replace on the content of all files
   # in a given directory
   #
   # Note - this code skips binary files

   use strict;
   use warnings;
   use File::Util qw( NL SL );

   # will get search pattern from file named below
   use constant SFILE => './sr/searchfor';

   # will get replace pattern from file named below
   use constant RFILE => './sr/replacewith';

   # will perform batch operation in directory named below
   use constant INDIR => '/foo/bar/baz';

   # create new File::Util object, set File::Util to send a warning for
   # fatal errors instead of dying
   my $ftl   = File::Util->new( onfail => 'warn' );
   my $rstr  = $ftl->load_file( RFILE );
   my $spat  = quotemeta $ftl->load_file( SFILE ); $spat = qr/$spat/;
   my $gsbt  = 0;
   my $opts  = { files_only => 1, with_paths => 1, recurse => 1 };
   my @files = $ftl->list_dir( INDIR => $opts );

   for (my $i = 0; $i < @files; ++$i) {

      next if $ftl->is_bin( $files[$i] );

      my $sbt = 0; my $file = $ftl->load_file( $files[$i] );

      $file =~ s/$spat/++$sbt;++$gsbt;$rstr/ge;

      $ftl->write_file( file => $files[$i], content => $file );

      print $sbt ? qq($sbt replacements in $files[$i]) . NL : '';
   }

   print NL . <<__DONE__ . NL;
   $gsbt replacements in ${\ scalar @files } files.
   __DONE__

   exit;

  Pretty-Print A Directory Recursively
This is the fool-proof, dead-simple way to pretty-print a directory tree. Caveat: This isn't a method for massive directory traversal, and is subject to the limitations inherent in stuffing an entire directory tree into RAM. Go back and use bare callbacks (see the other example scripts that came in the "examples" subdirectory of this distribution) if you need a more efficient, streaming (real-time) pretty-printer where top-level sorting is less important than resource constraints and speed of execution.

   # set this to the name of the directory to pretty-print
   my $treetrunk = '.';

   use warnings;
   use strict;

   use lib './lib';
   use File::Util qw( NL SL );

   my $ftl = File::Util->new( { onfail => 'zero' } );

   walk( $ftl->list_dir( $treetrunk => { as_tree => 1, recurse => 1 } ) );

   exit;

   sub walk
   {
      my ( $branch, $depth ) = @_;

      $depth ||= 0;

      talk( $depth - 1, $branch->{_DIR_SELF_} . SL ) if $branch->{_DIR_SELF_};

      delete @$branch{ qw( _DIR_SELF_  _DIR_PARENT_ ) };

      talk( $depth, $branch->{ $_ } ) for sort { uc $a cmp uc $b } keys %$branch;
   }

   sub talk
   {
      my ( $indent, $item ) = @_;

      return walk( $item, $indent + 1 ) if ref $item;

      print(  ( ' ' x ( $indent * 3 ) ) . ( $item || '' ) . NL );
   }

AUTHORS
Tommy Butler <http://www.atrixnet.com/contact>

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

LICENSE
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.

LIMITATION OF WARRANTY
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.

SEE ALSO
File::Util::Cookbook