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Env(3pm)                              Perl Programmers Reference Guide                              Env(3pm)



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("\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 ""."".

       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 v5.10.0                                     2007-12-18                                         Env(3pm)