Listing 2 The CommandLength.pl perl script

#!/usr/bin/perl -w

# $Id$
#
# Please note that this is alpha code
# Provided without any guarantees
#
# Programmer: Mihalis Tsoukalos
# Date: Monday 21 March 2006
#
# Command line arguments
# program_name.pl <directory with history files>

use strict;

my $directory = "";
my $filename = "";

# The variables for storing total number of commands
# by command length.
my $CAT1 = 0;
my $CAT2 = 0;
my $CAT3 = 0;
my $CAT4 = 0;
my $CAT5 = 0;

die <<Thanatos unless @ARGV;
usage:
    $0 directory
Thanatos

if ( @ARGV != 1 )
{
    die <<Thanatos
       usage info:
          Please use exactly 1 argument!
Thanatos
}

# Get the directory name
($directory) = @ARGV;

print "The following text files found in directoy: $directory\n";
opendir(BIN, $directory)
         || die "Error opening directory $directory: $!\n";

while (defined ($filename = readdir BIN) )
{
         # The following command does not process . and ..
         next if( $filename =~ /^\.\.?$/ );

         print $filename."\n";
         process_file($directory."/".$filename);
}

print "Category 1: $CAT1\n";
print "Category 2: $CAT2\n";
print "Category 3: $CAT3\n";
print "Category 4: $CAT4\n";
print "Category 5: $CAT5\n";

exit 0;

sub process_file
{
         my $file = shift;
         my $line = "";
         
         open (HISTORYFILE, "< $file")
                  || die "Cannot open $file: $!\n";
         
         while ( defined($line = <HISTORYFILE>) )
         {
                  chomp $line;
                  next if ( ! defined($line) );
                  check_category($line);
         }

}

sub check_category
{
         my $command = shift;
         chomp $command;
         
         my $length = length($command);
         
         if ( $length <= 2 )
         {
                  $CAT1 ++;
         }
         elsif ( $length <= 5 )
         {
                  $CAT2 ++;
         }
         elsif ( $length <= 10 )
         {
                  $CAT3 ++;
         }
         elsif ( $length <= 15 )
         {
                  $CAT4 ++;
         }
         else
         {
                  $CAT5 ++;
         }
}