#! /usr/bin/perl

use POSIX;

$old = shift || die "Bad usage\n";
$new = shift || die "Bad usage\n";

while ( $file = shift )
   {
   open( INFILE, "<$file" ) or die "Can't open file '$file'\n";
   print "Reading file '$file'\n";
   while ( <INFILE> )
      {
      &substitute if ( m&$old& );
      }
   close( INFILE );
   }

exit 0;

sub substitute
{
print "Substituting for file '$file'\n";
rewind( INFILE );
open( OUTFILE, ">$file.out" ) || die "Can't open file '$file.out'\n";
while ( <INFILE> )
   {
   s&$old&$new&;
   print OUTFILE;
   }
close( OUTFILE );
rename "$file.out", "$file";
}
