Shell Programming and Scripting

#!/usr/bin/perl
use strict;
use Cwd;
my $cwd = cwd;
my $file = $cwd . '/usrgrps.txt';
my $gid;
my $grp;
my $host;
my $group;
my $userid;
my %table = ();
open(FILE, "<", $file) or die "Can't open $file:$!";
while(<FILE>)
{
chomp;
($host, $grp, $gid, $userid) = split(/\:/, $_);
$group = "$grp:$gid";
my @users=split(/\,/,$userid);
if ( scalar(@users) )
{
foreach my $user ( @users )
{
   push(@{$table{$group}}, $user) if ( ! grep{/$user/} @{$table{$group}} );
}
}
else
{
push @{$table{$group}}, $userid;
}
}
#Open file in write mode
my $mOutfile=$cwd . '/outfile.txt';
if(open(OFILE,">","$mOutfile"))
{
foreach $group (sort keys %table) {
print OFILE "$group:";
my @users = @{$table{$group}};
print OFILE join ',', sort @users;
print OFILE "\n";
}
}
else
{
 print "Unable to open the file to write\n";
}