Here is a code snippet I use about 100 times a day:

 
my $filename = 'pathToFile.txt';
# Use the 3 arg form of open.
# Use 'my' to scope the file handle.
# die if we cannot open the file, report error in '$!'.
open my $input_fh, '<', $filename or 
   die "Could not open $filename: $!";

# Loop through each line in the file.
# Use 'chomp' to remove the trailing newline.

## Label your loops.  If you nest loops like I do, 
## your 'next' commands can reference  your label to make
## sure you short circuit the correct loop.
LINE:  while (my $line = <$input_fh>) {
    chomp $line;
    # Do stuff here with $line...

    # And later maybe you test something and need to skip
    # to the next line:
    if ($something_happens) {
        next LINE;
    }

}
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