foo=hello
fruit=apple
foo.bar=tunafish
color=red
baz=$foo.bar

##</code><code>##

baz=hello.bar

##</code><code>##

baz=tunafish

##</code><code>##

SCRIPT_DIR=/usr/local/scripts
MAIN_SCRIPT=$SCRIPT_DIR/main_script.pl

##</code><code>##

MAIN_SCRIPT=/usr/local/bin/scripts/main_script.pl

##</code><code>##

$value =~ s/\$ ( {\.+?} | \w+)/$config{$2}/gx;

##</code><code>##

foo=hello
fruit=apple
foo.bar=tunafish
color=red
baz=${foo.bar}