I like my configuration file to be written in perl, so I can have common functions which can be used between my programs.
   I start like this...

use lib ("/path/to/file/config");
use PerlConfig;  # This is PerlConfig.pm in /path/to/file/config
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     Then my config file starts like this...

package Cfg;
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     My program can now use variables with $Cfg:: in front of them, or subroutines with &Cfg:: in front of them so that I don't get confused about where things exist.
     For example, I want to have a consistent time/date stamp in all of my output file names. So, I use POSIX 'strftime' in my config file then set $filedt = sub { return strftime("%m%d%H%M%S", localtime) };
     I then use filenames like
my $logfile = "codelog_" . &$Cfg::filedt . ".txt";
GM