#!/usr/bin/perl -w

use strict;

my ($search, $replace, $fn, @data, $mod);
my $modified = 0;

die "usage: sar search-text replace-text files..."
	unless $search = shift;
die "usage: sar search-text replace-text files..."
	unless $replace = shift;

foreach $fn (@ARGV) {
	@data = ();
	$mod = 0;

	open(F, $fn) or die "$fn: $!\n";
	while (<F>) {
		if ($mod) {
			s/\b$search\b/$replace/go;
		}
		elsif (/\b$search\b/o) {
			$mod = 1;
			s/\b$search\b/$replace/go;
		}
		push(@data, $_);
	}
	close(F);

	if ($mod) {
		open(F, ">$fn") or die "$fn: $!\n";
		print F @data;
		close(F);
		$modified++;
	}
}

printf "%d files modified.\n", $modified;
exit(0);