File::DirWalk makes the directory recursion easy. Perl's builtins trivialize the rest. The canonical way to use DirWalk is something like so:
#!/usr/bin/env perl
use 5.014;
use warnings;
use File::DirWalk;
# Process commandline arguments
die "usage: $0 pattern path ..." if (@ARGV < 2);
my $pattern = shift;
# @ARGV now contains one or more paths to recurse
# Set up DirWalk object with callback to grep each file
my $dw = new File::DirWalk;
$dw->onFile(sub {
my $file = shift;
if (-T $file) {
open my $fh, '<', $file or die "Can't open $file: $!";
print map { "$file: $_" } grep { /$pattern/ } <$fh>;
close $fh;
}
return File::DirWalk::SUCCESS;
});
$dw->walk($_) for @ARGV;
The above gives you a very simple grep -R command. Probably more instructive than directly useful.
The -T operator is one of Perl's file test operators that evaluates to true if the file is an ASCII text file (based on some heuristic guesswork). There is an equivalent -B test for binary files.
