use strict; 
use warnings; 
my @files = glob 'file.*.1'; 
my @sorted_files = map {$_->[1]} 
    sort {$a->[0] <=> $b->[0]} 
        map {/\.(\d+)\./;[$1,$_]} 
            @files; 
open my $OUT, '>', 'mergefile.txt' or die "cannot open output file:$!"; 
foreach (@sorted_files) { 
    open my $FH, '<', $_ or die "Cannot open $_:$!"; 
    while (my $line = <$FH>) { 
        print {$OUT} join( ' ', (split)[0,1] ), "\n"; 
    } 
    close $FH; 
} 
close $OUT;