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

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

           use Env;
           use Env qw(PATH HOME TERM);
           use Env qw($SHELL @LD_LIBRARY_PATH);

       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 vari-
       ables ("keys %ENV") to scalars.  If the "import" function
       receives arguments, it takes them to be a list of vari-
       ables 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::Con-
       fig{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 ""."".

perl v5.8.5                 2002-11-06                          1

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

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

           undef $PATH;
           undef @LD_LIBRARY_PATH;

       On VMS systems, arrays tied to environment variables are
       read-only. Attempting to change anything will cause a

       Chip Salzenberg <chip@fin.uucp> and Gregor N. Purdy <gre-

perl v5.8.5                 2002-11-06                          2