Scripting problems with pipes!

Question

Hi Boardies!
I'm working on a script to automatically generate PKGBUILDs for my custom kernels (For my 3 systems I need 3 custom kernel packages).
Each PKGBUILD needs the md5 checksum block, which I can generate with "makepkg -c > PKGBUILD".
Here is the problem
This command writes the checksums at the end of the PKGBUILD file. This isn't a clean solution. The checksums should wrote before the "build()" function.
Because of that I need a trickly bash command, which search (grep maybe?) the "build() "-line and writes the md5-checksum block before that line.
I tested around with egrep, but I can't isolate the line-number of "build()" and I don't know how to paste the md5-checksums be at the position (line - 1)!
I hope somebody can help me. Thanks for your answers
Best regards,
Flasher

Answer 1

A simple perl script would be appropriate.  The easiest way to approach this problem (actual perl programmers feel free to correct me) is to do the following:
iterate over the file, pulling each line into a string appended to an array
iterate over the array, printing each line.  If build() is matched, print md5sum, then the line.
write the corrected file to stdout
Here's one I called test.pl
#!/usr/bin/perl
#Add MD5SUM to file
#Read from stdin into @file
while (<>) {
chomp;
push(@file, $_);
foreach my $a (@file) {
if ($a =~ /build\(\)/) {
print "MD5SUM\n";
print "$a\n";
Then the following command:
cat PKGBUILD | ./test.pl > temp
mv temp PKGBUILD
Produces an identical PKGBUILD with the word MD5SUM printed on the line above build().