Env - perl module that imports environment variables as scalars or arrays
use Env; use Env qw(PATH HOME TERM); use Env qw($SHELL @LD_LIBRARY_PATH);
Perl maintains environment variables in a special hash named %ENV. For when this access method is inconvenient, the Perl module Env allows environment variables to be treated as scalar or array variables.
%ENV
Env
The Env::import() function ties environment variables with suitable names to global Perl variables with the same names. By default it ties all existing environment variables (keys %ENV) to scalars. If the import function receives arguments, it takes them to be a list of variables to tie; it's okay if they don't yet exist. The scalar type prefix '$' is inferred for any element of this list not prefixed by '$' or '@'. Arrays are implemented in terms of split and join, using $Config::Config{path_sep} as the delimiter.
Env::import()
keys %ENV
import
split
join
$Config::Config{path_sep}
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.
The code:
use Env qw(@PATH); push @PATH, '.';
is equivalent to:
use Env qw(PATH); $PATH .= ":.";
except that if $ENV{PATH} started out empty, the second approach leaves it with the (odd) value ":.", but the first approach leaves it with ".".
$ENV{PATH}
:.
.
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 <chip@fin.uucp> and Gregor N. Purdy <gregor@focusresearch.com>
To install Env, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Env
CPAN shell
perl -MCPAN -e shell install Env
For more information on module installation, please visit the detailed CPAN module installation guide.