Lets your program treat environment variables as simple variables instead of having to access them from the %ENV pseudo-hash where they are kept. (Note that pseudo-hashes will disappear as of Perl 6.)
use Env; use Env qw(var1 var2 ...);
Internally, Env uses an import function that ties suitably named environment variables to global Perl variables with the same names. By default, it ties all variables yielded by keys %ENV. A "suitable" environment has a name that begins with an alphabetic character and contains only alphanumeric characters or underscores.
When use Env is invoked with arguments, the arguments are interpreted as a list of environment variables to tie, but the variables don't have to exist yet. After a variable has been tied, you can use it like a normal variable, accessing or changing its value.
You untie a variable by setting its value to undef.
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