Are you expecting the environment values to still be true after the script has run? If so, this will not work. The values can be set during the script but once it exits, the values disappear. Other people have noted this in your other posting.

use Data::Dumper;

## First show the current environment

 print "What does \%ENV look like now:\n";
 $Data::Dumper::Purity=1;
 print Data::Dumper->Dump([\%ENV], ['*ENV']);


## now we manually add an element to the ENV hash

 $key="JUST_A_TEST";
 $value='just_a_value';
 $key_1='ANOTHER_SILLY_KEY';

 $ENV{'EXAMPLE'}='12345_test';
 $ENV{$key}='yes_this_is_a_value';
 $ENV{'EXAMPLE4'}=$value;
 $ENV{$key_1}=$value;
 
## Show the current environment after setting manually

 print "What does \%ENV look like now:\n";
 $Data::Dumper::Purity=1;
 print Data::Dumper->Dump([\%ENV], ['*ENV']);

## Get the key/value pairs from DATA

open IN, "environment.txt" or die "Cannot open $input. $!";

foreach $pair (<DATA>) {
         ($key,$value)=split(/=/,$pair);
         $ENV{$key}=$value;
}#close foreach

## First show the current environment

 print "What does \%ENV look like now:\n";
 $Data::Dumper::Purity=1;
 print Data::Dumper->Dump([\%ENV], ['*ENV']);

#the following data is read from DATA but could be put into "environme
+nt.txt" and used from there too.
__DATA__
EXAMPLE2=test_test_test_1234567890
EXAMPLE3=a_very_modern_major_sample_of_a_has_value
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