1Env(3)                User Contributed Perl Documentation               Env(3)
2
3
4

NAME

6       Env - perl module that imports environment variables as scalars or
7       arrays
8

SYNOPSIS

10           use Env;
11           use Env qw(PATH HOME TERM);
12           use Env qw($SHELL @LD_LIBRARY_PATH);
13

DESCRIPTION

15       Perl maintains environment variables in a special hash named %ENV.  For
16       when this access method is inconvenient, the Perl module "Env" allows
17       environment variables to be treated as scalar or array variables.
18
19       The "Env::import()" function ties environment variables with suitable
20       names to global Perl variables with the same names.  By default it ties
21       all existing environment variables ("keys %ENV") to scalars.  If the
22       "import" function receives arguments, it takes them to be a list of
23       variables to tie; it's okay if they don't yet exist. The scalar type
24       prefix '$' is inferred for any element of this list not prefixed by '$'
25       or '@'. Arrays are implemented in terms of "split" and "join", using
26       $Config::Config{path_sep} as the delimiter.
27
28       After an environment variable is tied, merely use it like a normal
29       variable.  You may access its value
30
31           @path = split(/:/, $PATH);
32           print join("\n", @LD_LIBRARY_PATH), "\n";
33
34       or modify it
35
36           $PATH .= ":.";
37           push @LD_LIBRARY_PATH, $dir;
38
39       however you'd like. Bear in mind, however, that each access to a tied
40       array variable requires splitting the environment variable's string
41       anew.
42
43       The code:
44
45           use Env qw(@PATH);
46           push @PATH, '.';
47
48       is equivalent to:
49
50           use Env qw(PATH);
51           $PATH .= ":.";
52
53       except that if $ENV{PATH} started out empty, the second approach leaves
54       it with the (odd) value "":."", but the first approach leaves it with
55       ""."".
56
57       To remove a tied environment variable from the environment, assign it
58       the undefined value
59
60           undef $PATH;
61           undef @LD_LIBRARY_PATH;
62

LIMITATIONS

64       On VMS systems, arrays tied to environment variables are read-only.
65       Attempting to change anything will cause a warning.
66

AUTHOR

68       Chip Salzenberg <chip@fin.uucp> and Gregor N. Purdy
69       <gregor@focusresearch.com>
70
71
72
73perl v5.32.1                      2021-01-27                            Env(3)