File Splitter

Jan 18
2008
Comments Off 
use strict;
use Getopt::Std;
use File::Basename;
 
getopts('scf:p:');
 
our($opt_s, $opt_c, $opt_f, $opt_p);
 
my $file = $opt_f;
my $size = $opt_p || 1;
my $len  = 1024;
my $c = 1;
my ($buf, $counter);
 
-f $file or usage();
 
if($opt_s){
    $size = 1024 * $size;
 
    open IN, "< $file" or die "cannot open_r $file $!";
    open OUT, "> $file.$c"  or die "cannot open_w $file $!";
    binmode IN;
    binmode OUT;
 
    while(read(IN, $buf, $len)){
        $counter++;
        if($counter > $size){
            $counter = 0;
            $c++;
            close OUT;
            open OUT, "> $file.$c"  or die "cannot open_w $file $!";
            binmode OUT;
        }
        print OUT $buf
    }
} elsif($opt_c) {
    my @files = grep { -f and /^$file\.\d+$/ } glob '*';
    my $newfile = "splitter_$file";
    open OUT, ">> $newfile" or die "cannot open_w $file $!";
    binmode OUT;
    map { $_ =~ s/^$file\.// } @files;
    for(sort {$a< =>$b} @files ){
        open IN, "$file.$_" or die "cannot open_r $file $!";
        binmode IN;
        print OUT $_ while <in>;
        close IN;
    }
} else {
    usage()
}
 
sub usage{
    my $pro = basename($0);
    print < <SQ;
 
$pro (-s|-c) -p piece size -f filename
 
    -s    split a file into pieces
    -c    collect a file from pieces
    -p     chunk size (defaults to 1MB)
    -f     file to be processed
SQ
    exit 1
}

Written by Vidul in: Perl, scripts | Tags:

String Iterator

Jan 14
2008
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class String
  class Iterator < String
 
    def initialize(str='', next_char=0)
      @next_char = next_char
      super(str)
    end
 
    def next
      return nil if @next_char > self.size
 
      @next_char += 1
 
      get_char(-1)
    end
 
    def prev
      return nil if @next_char < = 0
 
      @next_char -= 1 if @next_char > 0
 
      get_char()
    end
 
    private
    def get_char(pos=0)
      if block_given?
        yield split(//)[@next_char+(pos)]
      else
        split(//)[@next_char+(pos)]
      end
    end
  end
end
 
s = String::Iterator.new "abcdef"
 
while char = s.next
  puts char
end
 
while char = s.prev
  puts char
end
Written by Vidul in: Ruby, senseless |

Getting Ruby Include Path

Jan 13
2008
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$LOAD_PATH === $: #true, hence

irb

puts$:.sort
 
__END__
.
/usr/lib/ruby/1.8
/usr/lib/ruby/1.8/i386-linux
/usr/lib/ruby/1.8/i486-linux
/usr/local/lib/site_ruby
/usr/local/lib/site_ruby/1.8
/usr/local/lib/site_ruby/1.8/i386-linux
/usr/local/lib/site_ruby/1.8/i486-linux
Written by Vidul in: Ruby |

File.rename(tedious part of the filename)

Jan 13
2008
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Rename each file in each sub-directory, substituting ‘%20’ with ’ ‘(space).

class File
  def self.rename_basename(abs_name, old_str, new_str)
    f_name = File.basename(abs_name).gsub Regexp.quote(old_str), new_str
    d_name = File.dirname(abs_name)
    File.rename(abs_name, d_name + '/' + f_name)
    rescue
      raise ArgumentError, "No such file #{filename}", caller
  end
end
 
Dir["*/**"].each do |f|
  if File.basename(f).match('%20')
    File.rename_basename(f, '%20', ' ')
  end
end
Written by Vidul in: Ruby, scripts | Tags:

Sort By Part Of Filename

Jan 12
2008
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Assume that we have directory, containing files like:

part_1.txt
part_2.txt
part_100.txt
part_200.txt

In case that we are interested in /(\d+)\.\w+$/ as part of the sorting criteria:

Perl

# short but unefficient
@a = sort {($a =~ /(\d+)\.\w+$/)[0] < => ($b =~  /(\d+)\.\w+$/)[0]} < *>;

Ruby

regex = Regexp.new(/(\d+)\.\w+$/)
 
# enum.sort {| a, b | block } => array
Dir["*"].grep(regex).sort do |a, b|
  a.match(regex)[0].to_i < => b.match(regex)[0].to_i
end
 
# enum.sort_by {| obj | block } => array
Dir["*"].grep(regex).sort_by do |name|
  name.match(regex)[1].to_i
end
Written by Vidul in: Perl, Ruby, programming, sorting | Tags:

Dynamically Define Methods

Jan 11
2008
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Perl

package MyClass;
package main;
 
*MyClass::from_my_class = sub {
   print "defined in ", __PACKAGE__, "\n"
};
 
MyClass::from_my_class();

Ruby

class String
  def self.from_string
    print "defined in " + self.name + $/
  end
end
 
String::from_string
String. from_string
Written by Vidul in: OOP, Perl, Ruby | Tags: ,

perldoc usage

Jan 09
2008
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function manual:

perldoc -f grep

search the text in perlfaq:

perldoc -q grep

module content:

perldoc -m IO::Socket

module absolute filename:

perldoc -l IO::Socket

and of course:

perldoc perl
Written by Vidul in: Perl, SA | Tags:

Special characters in file name

Jan 09
2008
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Safely manipulate file with special characters in the name:

ruby -rfileutils -e 'FileUtils.rm_r "~"'
Written by Vidul in: Ruby, SA |

Just_Another_Perl_Hacker.pm

Jan 08
2008
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package Just_Another_Perl_Hacker; $$
perl -MJust_Another_Perl_Hacker -e 's|(?< =\w)_| |g && tr/:://d && print for keys %main::'
Written by Vidul in: JAPH, Perl |

“Argument list too long”

Jan 08
2008
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Given that linuxjournal has some good points, there is no need for another solution, except in the cases when you operate on different machine. Here is oneliner solution:

irb console #remove Opera cached files

too_many_files = "~/.opera/cache4/"
 
Dir.new(too_many_files_dir).each do |f|
  File.file?(f) && File.unlink(f)
end
Written by Vidul in: Ruby, SA |
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