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.\" -*- mode: troff; coding: utf-8 -*-
.\" Automatically generated by Pod::Man 5.01 (Pod::Simple 3.43)
.\"
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.\" ========================================================================
.de Sp \" Vertical space (when we can't use .PP)
.if t .sp .5v
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..
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.ft CW
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.\"
.\" If the F register is >0, we'll generate index entries on stderr for
.\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index
.\" entries marked with X<> in POD. Of course, you'll have to process the
.\" output yourself in some meaningful fashion.
.\"
.\" Avoid warning from groff about undefined register 'F'.
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.\" ========================================================================
.\"
.IX Title "Env 3perl"
.TH Env 3perl 2024-02-11 "perl v5.38.2" "Perl Programmers Reference Guide"
.\" For nroff, turn off justification. Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH NAME
Env \- perl module that imports environment variables as scalars or arrays
.SH SYNOPSIS
.IX Header "SYNOPSIS"
.Vb 3
\& use Env;
\& use Env qw(PATH HOME TERM);
\& use Env qw($SHELL @LD_LIBRARY_PATH);
.Ve
.SH DESCRIPTION
.IX Header "DESCRIPTION"
Perl maintains environment variables in a special hash named \f(CW%ENV\fR. For
when this access method is inconvenient, the Perl module \f(CW\*(C`Env\*(C'\fR allows
environment variables to be treated as scalar or array variables.
.PP
The \f(CWEnv::import()\fR function ties environment variables with suitable
names to global Perl variables with the same names. By default it
ties all existing environment variables (\f(CW\*(C`keys %ENV\*(C'\fR) to scalars. If
the \f(CW\*(C`import\*(C'\fR function receives arguments, it takes them to be a list of
variables to tie; it's okay if they don't yet exist. The scalar type
prefix '$' is inferred for any element of this list not prefixed by '$'
or '@'. Arrays are implemented in terms of \f(CW\*(C`split\*(C'\fR and \f(CW\*(C`join\*(C'\fR, using
\&\f(CW$Config::Config{path_sep}\fR as the delimiter.
.PP
After an environment variable is tied, merely use it like a normal variable.
You may access its value
.PP
.Vb 2
\& @path = split(/:/, $PATH);
\& print join("\en", @LD_LIBRARY_PATH), "\en";
.Ve
.PP
or modify it
.PP
.Vb 2
\& $PATH .= ":/any/path";
\& push @LD_LIBRARY_PATH, $dir;
.Ve
.PP
however you'd like. Bear in mind, however, that each access to a tied array
variable requires splitting the environment variable's string anew.
.PP
The code:
.PP
.Vb 2
\& use Env qw(@PATH);
\& push @PATH, \*(Aq/any/path\*(Aq;
.Ve
.PP
is almost equivalent to:
.PP
.Vb 2
\& use Env qw(PATH);
\& $PATH .= ":/any/path";
.Ve
.PP
except that if \f(CW$ENV{PATH}\fR started out empty, the second approach leaves
it with the (odd) value "\f(CW\*(C`:/any/path\*(C'\fR", but the first approach leaves it with
"\f(CW\*(C`/any/path\*(C'\fR".
.PP
To remove a tied environment variable from
the environment, assign it the undefined value
.PP
.Vb 2
\& undef $PATH;
\& undef @LD_LIBRARY_PATH;
.Ve
.SH LIMITATIONS
.IX Header "LIMITATIONS"
On VMS systems, arrays tied to environment variables are read-only. Attempting
to change anything will cause a warning.
.SH AUTHOR
.IX Header "AUTHOR"
Chip Salzenberg <\fIchip@fin.uucp\fR>
and
Gregor N. Purdy <\fIgregor@focusresearch.com\fR>
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