kinda goofy, but it helps when breaking up large patches (esp. useful when trying to update an old linux kernel patch to a newer kernel and things just don't line up...) :

#!/usr/bin/perl

if ( ! @ARGV ) {
 print "Usage : $0 patch1 patch2 ...\n";
 exit 1;
}

# path to put output in
$outputroot = $ENV{"HOME"};
$outputdir = "$outputroot/patch-divide";

if ( ! -d $outputdir ) {
 mkdir("$outputdir",0777)
}

foreach $patch ( @ARGV ) {
 $outputbase = "$outputdir/$patch";
 open(INPUT,"$patch") || die "Can't open $patch : $! \n";
 $count = 0;
 while(<INPUT>) {
  if(!<OUTPUT>) {
   open(OUTPUT,">>$outputbase.$count") || die "No output";
  }
  if (!/^diff/) {
   print OUTPUT;
  } else {
  ( $count == 0 ) && print OUTPUT "$patch";
  $count++;
  close(OUTPUT) || warn "Couldn't close : $!\n";
  }
 }
}

close(INPUT);
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