Re: Re: Re: Extracting Header

[Chmrr]

I'm guessing that you want to "cut" the header lines out of the file, editing the file and leaving it with only the data in it. Here's the gradual evolution of something that will do that:

First off, we need to get a general plan. We want to read in the file line by line, and make a new file as we do so -- the trick is to not print the line if it's a header line. This means our new file will only have the data in it. So here's something that does that:

#!/usr/bin/perl -w;
open IN, "file.in" or die "file.in: $!";
open OUT, ">file.out" or die ">file.out: $!"
while (<IN>) {
  if ($_ =~ /^\d/) {
    print OUT $_;
  }
}
close IN;
close OUT;

Next step is to make this code a little classier. First off, we can use the -n and -i command line options to make this a lot shorter. The -n does the work of the while loop, and the -i does the word of making a new file, and then replacing the original. It'll even keep a backup for you! Here's what it looks like using -ni, then:

#!/usr/bin/perl -ni.bak
if ($_ =~ /^\d/) {
  print $_;
}

..Which can be condensed and made a lot more canonical:

perl -ni.bak -e 'print if /^\d/' file.dat

Voila!

Update: Manythanks to ChemBoy. I said -ni in two places, then gradually drifted off to saying -pi. Oopsie.

perl -pe '"I lo*`+$^X$\"$]!$/"=~m%(.*)%s;$_=$1;y^`+*^e v^#$&V"+@( NO CARRIER'