Programming

perl -ne 'print if s|^<certificate FullCert="(.*)"/>|$1|' file.xml

#!/usr/bin/perl
use strict;
use warnings;

open my ($in_fh), '<', 'infile.xml'
or die "Could not open input file: $!\n";

my %certs;

while(<$in_fh>) {
 push ( @{$certs{$2}}, $1) if (my ($cert, $name) = /^<certificate FullCert="([^"]+)".* name="([^"]+)"/);
}

close $in_fh;

for my $cert_name (keys %certs) {
 open my $out_fh, '>', $cert_name
 or warn "Could not open output file ($cert_name): $!\n";
 printf $out_fh "%s\n", $_ for (@{$certs{$cert_name}});
}