centos man page for env

Env(3)							User Contributed Perl Documentation						    Env(3)

NAME
       Env - perl module that imports environment variables as scalars or arrays

SYNOPSIS
	   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

	   @path = split(/:/, $PATH);
	   print join("
", @LD_LIBRARY_PATH), "
";

       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 ""."".

       To remove a tied environment variable from the environment, assign it the undefined value

	   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>

perl v5.16.3							    2013-03-02								    Env(3)