#!/usr/local/bin/perl 
if ($#ARGV < 2)
   {
    print<<"end_tag";
    
# $0 opens a file for reading and changes a name in the file
# use: $0 OLD_NAME NEW_NAME FILE_LIST
#      param 1 is the old value 
#      param 2 is the new value 
#      param +2 is file list. There is no programatic limit to the number of files processed
# the original file will be copied into a .bak file
# the original file will be overwritten with the substitution
# the script assumes the file(s) to be modified are in the directory that the 
# script was started from
# SYMBOLIC LINKS are NOT followed
end_tag
    exit(1);
   }

$OLD = shift; # dump arg(0) 
$NEW = shift; # dump arg(1) 
# now argv has just the file list in it.
 
select(OUTFILE);
while (<>)
   {
    next if -l $ARGV; #skip this file if it is a sym link
    $count++ ;
    print STDOUT "." if (($count % 10) == 0);

    if ($ARGV ne $oldargv) #have we saved this file ?
       {
       close(OUTFILE);
       print STDOUT "\nprocessing $ARGV ...";   
       $count = 0 ;
       rename($ARGV, $ARGV . '.bak'); #mv the file to a backup copy
       $oldargv = $ARGV ;
       open (OUTFILE, ">$ARGV");# open the file for writting
       }
    s/$OLD/$NEW/go;# perform substitution
                   # o - only interpret the variables once 
    print; #dump the file back into itself with changes
    }
close(OUTFILE);
select(STDOUT);
print "\n";