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Updated: Thursday, June 13, 2019
 
 

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 Programmers Reference Guide                                        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("\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>



ATTRIBUTES
       See attributes(7) for descriptions of the following attributes:


       +---------------+-----------------------+
       |ATTRIBUTE TYPE |   ATTRIBUTE VALUE     |
       +---------------+-----------------------+
       |Availability   | runtime/perl-526      |
       +---------------+-----------------------+
       |Stability      | Pass-through volatile |
       +---------------+-----------------------+
NOTES
       This software was built from source available at
       https://github.com/oracle/solaris-userland.  The original community
       source was downloaded from
       http://www.cpan.org/src/5.0/perl-5.26.3.tar.bz2

       Further information about this software can be found on the open source
       community website at http://www.perl.org/.



perl v5.26.3                      2018-03-01                            Env(3)