Question

I want to compare two big files with different column and row numbers and print those line which have a common word (like KJ):

file1:

XT1 123 aa NR
XT2 444 bb GF 
XT3 666 aa KJ

file2

fc KK pcn
wd CC KJ

output

XT3 666 aa wd CC KJ

I tried but I didn’t get anything:

awk 'FNR==NR{a[$4]=$3;next}{if (a[$3])print a[$3],$0}' file1 file2

Thank you in advance for your help

Answer 1

Based on the limited info you provided,

my $file1 = '...';
my $file2 = '...';

my %file2;
{
   open(my $fh2, '<', $file2)
      or die("Can't open \"$file2\": $!\n');
   while (<$fh2>) {
      my @F = split;
      $file2{$F[2]} = join(' ', @F[0,1]);
   }
}

{
   open(my $fh1, '<', $file1)
      or die("Can't open \"$file1\": $!\n');
   while (<$fh1>) {
      my @F = split;
      print(join(' ', @F[0..2], $file2{$F[3]}, $F[3]), "\n")
         if $file2{$F[3]};
   }
}

I assumed the following:

• file2 fits in memory as a hash of lines.
• A keyword doesn’t appear twice in file2.
• You’re only interested in matching the 4th column of file1 with the 3rd column of file2.

It maintains the order of the lines as they appear in file1.