File 1 ID121 ABC14 ID122 EFG87 ID145 XYZ43 ID157 TSR11 ID181 ABC31 ID962 YTS27 ID567 POH70 ID921 BAMD80 File 2 ID111 RET61 ID157 TSR11 ID181 ABC31 ID962 YTS27 ID452 FYU098 ID121 ABC14 ID122 EFG87 File 3 ID121 ABC14 ID612 FLOW12 ID122 EFG87 ID745 KIDP36 ID145 XYZ43 ID157 TSR11 ......... File 25 ID122 EFG87 ID809 EYE24 ID157 TSR11 ID921 BAMD80 ID389 TOP30 ID121 ABC14 Output: ID121 ABC14 ID122 EFG87 ID157 TSR11 #### #!/usr/bin/perl use strict; use warnings; my %result; my @counts=(); foreach (@ARGV) { my $column=0; open my A, "<", "@counts "could not open file1 $!"; while () { chomp; my $key = (split /\t/, $_)[0]; $result{$key} = 1; $result{$key}++; if ($result{$key} == 20 { print "Line with $key is present in all twenty \n"; } } close (A); }; foreach (@counts) { s/^\s//g; print $_,"\n"; };