open FILE, $filename or die "$0: cannot open $filename for input: $!\n";
# two notes
# 1. Put as much information as possible in the die string
#    as you can lay your hands on.
# 2. That's \n, not /n, but I guess you realised that already...
while( <FILE> ) {
  # possibly...
  chomp;
  # otherwise do what you want with $_
}
close FILE;