print "The Perl Script does the User health check and system health check...\n";
print "---------------------------------------------------------------------\n";
# use strict;
my($OS);
$OS = $^O;
# need to test @ARGV before GetOptions shifts it
if (@ARGV == 0) {
   print "\nNo options provided, using defaults (use -h to view options)\n";
}
 
#GetOptions( 'h|help' => \$_help
        #   ,'u|userdata' => \$_userdata
        #   ,'s|systemdata' => \$_systemdata
		 #  ,'a|authresponsecode' => \$_authresponsecode
		 #  ,'o|outpur_dir' => \$_output_dir);
 
#if( $_help ) {
  # printUsage(); # automatically exits the program
#}
use Getopt::Std;
 
 
##############################################################################
# Print the usage info and automatically exit
##############################################################################
sub printUsage() {
   print "\n\nUsage:";
   print "\n  perl MSLogStat.pl [options] [logfile1] [logfile2] ... [logfile(n)]";
   print "\n\nOptions:";
   print "\n  -h            * display usage help";
   print "\n  -o            * redirect the output to a directory";
   print "\n  -u            * display user related data";
   print "\n  -a            * display auth response codes";
   print "\n  -s            * output only system related data";
   print "\n";
   exit;
}
##############################################################################
# Print the authresponsecode
##############################################################################
sub authResponseCode () {
	print "AAFW_AUTH_SUCCESS				= 0";
	print "AAFW_AUTH_MORESTEPS				= 1";
	print "AAFW_AUTH_ID_NOT_FOUND			= 2";
	print "AAFW_AUTH_INVALID_CREDENTIAL	    = 3";
	print "AAFW_AUTH_ACCOUNT_EXPIRED		= 4";
	print "AAFW_AUTH_ACCOUNT_INACTIVE		= 5";
	print "AAFW_AUTH_ATTEMPTS_EXHAUSTED	    = 6";
	print "AAFW_AUTH_TOKEN_EXPIRED			= 7";
	print "AAFW_AUTH_CHALLENGE_EXPIRED		= 8";
	print "AAFW_AUTH_INVALID_REQUEST		= 9";
	print "AAFW_AUTH_CRED_REISSUED			= 10";
	print "AAFW_AUTH_INTERNAL_ERROR		    = 11";
	print "AAFW_AUTH_UNSUPPORTED_MECH		= 12";
    print "AAFW_AUTH_LAST					= 13";
}
# redirect output to a directory:
if( $_output_dir ) {	
   # does this directory already exist?
   if (! -e $_output_dir) {
      if( $OS =~ "Win32" ) {
      	`mkdir $_output_dir`;
      }
      else
      {
      	`mkdir -p $_output_dir`;      	
      }
   }
   if (! -e $_output_dir) {
      die "Failed to create output directory $_output_dir\n";
   }
}
 
if( $_authresponsecode ) {
	print "Printing the Auth Response Codes";
	authresponsecode();
}
 
sub userData() {
   #$LOG = $_logfile_name;
   $username=$2;
   open($LOG,"logfile.txt") or die "\nUnable to open log file:\n";
   @stock = <$LOG>; 
   @matches = (grep(/$username/, @stock));
   print @matches;
}
my $opt = "hu:sao";
my %options;
getopts( $opt , \%options );
printUsage() if  defined  $options{h} ;
authResponseCode() if defined  $options{a} ;
userData() if defined  $options{u} ;

Getopt::Std

getopts("a:b:u:hs");
 
for example. That will automatically put -a data into the variable $opt_a. h and s will be switches and if set (-h for example) will set $opt_h = 1.

use Getopt:Std;
getopts("u:"); #the colon makes it an input field vs a switch
$username=$opt_u;