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Env(3)                 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(1,8) a special hash named(5,8) %ENV.  For
       when this access(2,5) 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(3,n) 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(1,8) terms of "split(1,n)" and "join(1,n)", using
       $Config::Config{path_sep} as the delimiter.

       After an environment variable is tied, merely use it like a normal
       variable.  You may access(2,5) its value

           @path = split(1,n)(/:/, $PATH);
           print join(1,n)("\n", @LD_LIBRARY_PATH), "\n";

       or modify it

           $PATH .= ":.";
           push @LD_LIBRARY_PATH, $dir;

       however you'd like. Bear in(1,8) mind, however, that each access(2,5) to a tied
       array variable requires splitting the environment variable's string(3,n)
       anew.

       The code:

           use Env qw(@PATH);
           push @PATH, '.';

       is equivalent to:

           use Env qw(PATH);
           $PATH .= ":.";

       except that if(3,n) $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@focusre-
       search.com>



perl v5.8.5                       2001-09-21                            Env(3)