Find content of one file from another file in UNIX

Question

I have 2 files. First file contains the list of row ID\'s of tuples of a table in the database. And second file contains SQL queries with these row ID\'s in \"where\" clause

Answer 1

I suggest using a programming language such as Perl, Ruby or Python.

In Ruby, a solution reading both files (f1 and f2) just once could be:

idxes = File.readlines('f1').map(&:chomp)

File.foreach('f2') do | line |
  next unless line =~ /where ri=(\d+);$/
  puts line if idxes.include? $1
end

or with Perl

open $file, '<', 'f1';
while (<$file>) { chomp; $idxs{$_} = 1; }
close($file);

open $file, '<', 'f2';
while (<$file>) {
    next unless $_ =~ /where ri=(\d+);$/;
    print $_ if $idxs{$1};
}
close $file;