```{index} single: Env ``` # Env perl module that imports environment variables as scalars or arrays ## SYNOPSIS ```perl use Env; use Env qw(PATH HOME TERM); use Env qw($SHELL @LD_LIBRARY_PATH); ``` ## DESCRIPTION Perl maintains environment variables in a special hash named `%ENV`. For when this access method is inconvenient, the Perl module `Env` allows environment variables to be treated as scalar or array variables. The `Env::import()` function ties environment variables with suitable names to global Perl variables with the same names. By default it ties all existing environment variables (`keys %ENV`) to scalars. If the `import` function receives arguments, it takes them to be a list of variables to tie; it's okay if they don't yet exist. The scalar type prefix '$' 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. After an environment variable is tied, merely use it like a normal variable. You may access its value ```perl @path = split(/:/, $PATH); print join("\n", @LD_LIBRARY_PATH), "\n"; ``` or modify it ```perl $PATH .= ":/any/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: ```perl use Env qw(@PATH); push @PATH, '/any/path'; ``` is almost equivalent to: ```perl use Env qw(PATH); $PATH .= ":/any/path"; ``` except that if `$ENV{PATH}` started out empty, the second approach leaves it with the (odd) value "`:/any/path`", but the first approach leaves it with "`/any/path`". To remove a tied environment variable from the environment, assign it the undefined value ```perl undef $PATH; undef @LD_LIBRARY_PATH; ``` ## LIMITATIONS On VMS systems, arrays tied to environment variables are read-only. Attempting to change anything will cause a warning. ## AUTHOR Chip Salzenberg <`chip@fin.uucp`> and Gregor N. Purdy <`gregor@focusresearch.com`>