Shell Programming and Scripting

Process is a program under execution but thread is a light weight process which has separate way of execution.

a
execution
but
has
is
light
of
process
program
separate
thread
under
way
weight
which

$ cat input-file
process is a program under execution but thread is a light weight process which has separate way of execution.

$ tr ' ' '\n' < input-file | sort | uniq
a
but
execution
execution.
has
is
light
of
process
program
separate
thread
under
way
weight
which

#!/usr/bin/perl

use strict;

my %seen;     # hash used to store how many times a word has been seen.
my @a_word;   # array to store uniq words.
my $word;     # variable to store each word.

#
# Loop through all lines in the file
#
while (<>)
{

   #
   # Split each line and proces each word.
   #
   for $word (split)
   {

      #
      # Change the word to lowercase.
      #
      $word = "\L$word";

      #
      # Create or increment the hash for the word.
      # This lets the hash act as a word counter as well.
      #
      $seen{$word}++;

      #
      # If this is the first time the word has been seen.
      # add the word to the arraw of words.
      #
      if ($seen{$word} == 1)
      {
         push( @a_word, $word );
      }
   }
}

#
# Sort the contents of the array of words.
#
@a_word = sort(@a_word);

#
# Print out each word and the number of times it was found.
#
foreach (@a_word)
{
   print "$_ $seen{$_}\n";
}

exit
#
# end of wc.pl
#