How to take out certain elements from a pdb file - bash

Question

I am trying to take out certain columns from a pdb file. I already have taken out all lines that start out with ATOM in my code. For some reason my sub functions are not working and I do not know where or how to call them.
My code is:
open (FILE, $ARGV[0])
or die "Could not open file\n";
my #newlines;
while ( my $line = <FILE> ) {
if ($line =~ m/^ATOM.*/) {
push #newlines, $line;
}
}
my $atomcount = #newlines;
#print "#newlines\n";
#print "$atomcount\n";
##############################################################
#This function will take out the element from each line
#The element is from column 77 and contains one or two letters
sub atomfreq {
foreach my $record1(#newlines) {
my $element = substr($record1, 76, 2);
print "$element\n";
return;
}
}
################################################################
#This function will take out the residue name from each line
#The element is from column 18 and contains 3 letters
sub resfreq {
foreach my $record2(#newlines) {
my $residue = substr($record2, 17, 3);
print "$residue\n";
return;
}
}

Answer 1

As #Ossip already said in this answer you simply need to call your functions:
sub atomfreq {
...
}
sub resfreq {
...
}
atomfreq();
resfreq();
But I'm not sure whether these functions do what you intended because the comments imply that they should print every $residue and $element from the #newlines array. You've put a return statement inside the for loop which will immediately return from the whole function (and its for loop) so it will print only the first $residue or $element. Because the functions aren't supposed to return anything you can just drop that statement:
sub atomfreq {
foreach my $record1(#newlines) {
my $element = substr($record1, 76, 2);
print "$element\n";
}
}
sub resfreq {
foreach my $record2(#newlines) {
my $residue = substr($record2, 17, 3);
print "$residue\n";
}
}
atomfreq();
resfreq();

Answer 2

You can just call them right under your other code like this:
atomfreq();
resfreq();