Env - perl module that imports environment variables as scalars or arrays
use Env; use Env qw(PATH HOME TERM); use Env qw($SHELL @LD_LIBRARY_PATH);
Perl maintains environment variables in a special hash named
%ENV. For when this access method is inconvenient, the Perl module
Env allows environment variables to be treated as scalar or array variables.
Env::import() function ties environment variables with suitable names to global Perl variables with the same names. By default it ties all existing environment variables (
keys %ENV) to scalars. If the
import function receives arguments, it takes them to be a list of variables to tie; it's okay if they don't yet exist. The scalar type prefix '$' is inferred for any element of this list not prefixed by '$' or '@'. Arrays are implemented in terms of
as the delimiter.
After an environment variable is tied, merely use it like a normal variable. You may access its value
@path = split(/:/, $PATH); print join("\n", @LD_LIBRARY_PATH), "\n";
or modify it
$PATH .= ":."; push @LD_LIBRARY_PATH, $dir;
however you'd like. Bear in mind, however, that each access to a tied array variable requires splitting the environment variable's string anew.
use Env qw(@PATH); push @PATH, '.';
is equivalent to:
use Env qw(PATH); $PATH .= ":.";
except that if
started out empty, the second approach leaves it with the (odd) value "
:.", but the first approach leaves it with "
To remove a tied environment variable from the environment, assign it the undefined value
undef $PATH; undef @LD_LIBRARY_PATH;
On VMS systems, arrays tied to environment variables are read-only. Attempting to change anything will cause a warning.
Chip Salzenberg <email@example.com> and Gregor N. Purdy <firstname.lastname@example.org>