###### with auto die ######
open XXX, '<', "XXX";
#Can't open 'XXX' for reading: 'No such file or directory' at C:\Projects_Perl\testing\die_messasges.pl line 7

###### without auto die ###
# trailing \n in the die message suppresses the line number.
open XXX, '<', "XXX" or die "couldn't open Config file, XXX!\n";
# couldn't open Config file, XXX!

open XXX, '<', "XXX" or die "couldn't open XX file!";
#couldn't open XX file! at C:\Projects_Perl\testing\die_messasges.pl line 5.

open XXX, '<', "XXX" or die "couldn't open config file XX!, $!";
# couldn't open config file XX!, No such file or directory at C:\Projects_Perl\testing\die_messasges.pl line 6.