use IO::File;
open (INPUT_FILE, $ARGV[0]) || die "cant open file\n";
my @body = <INPUT_FILE>;
my $count= 0;
$no_of_lines=scalar(@body);

for ( $i = 0 ; $i < $no_of_lines ; $i++)
{
$variable = $body[$i];

if ( $variable =~ "field1")
{

 print "$field1,"; 
}
if ( $variable =~ "field2")
{
 print "$field2,"; 
}
if ( $variable =~ "field2")
{
 print "$field2,"; 

}
...
...
}
close file;