Trying to process the two files in parallel is a bad idea. Assuming that text2 is not huge, read it first and create a hash entry for each file entry.

Then read text1 and use the hash to check to see if there is a matching entry in text2:

use strict;
use warnings;

my $text1 = <<'END_TEXT';
2343/45/45/cal/ca-1.xml     2343/45/45/ca-1
6534/534/34/car/ca-5.xml     6534/534/34/ca-5
END_TEXT

my $text2 = <<'END_TEXT';
6534/534/34/ca-5
5676/435/734/da-1
END_TEXT

my %text2Entries;

# Build a hash table of text2 entries
open my $inFile, '<', \$text2 or die "Unable to read text2: $!\n";
while (<$inFile>) {
    chomp;
    ++$text2Entries{lc $_};
}
close $inFile;

# Read the text1 entries and print any that don't have a text2 entry
open $inFile, '<', \$text1 or die "Unable to read text1: $!\n";
while (my $line = <$inFile>) {

    my ($part1, $part2) = split /\s+/, $line;

    chomp $part2;
    next if ! exists $text2Entries{lc $part2};
    print $line;
}
close $inFile;

[download]

Prints:

6534/534/34/car/ca-5.xml     6534/534/34/ca-5

[download]

Don't get hung up on the two $text strings - that's just so I can provide a runnable test script without requiring external files.

True laziness is hard work

In reply to Re: Read two files and print by GrandFather
in thread Read two files and print by sandy1028

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