=head1 NAME

PAR::Environment - Index and reference of PAR environment variables

=head1 DESCRIPTION

PAR uses various environment variables both during the building process of
executables or PAR archives and the I<use> of them. Since the wealth of
combinations and settings might confuse one or the other (like me), this
document is intended to document all environment variables which PAR uses.

Wherever I want to refer to the C<$ENV{FOO}> environment hash entry, I will
usually talk about the C<FOO> variable for brevity.

=head1 INDEX OF ENVIRONMENT VARIABLES

B<Please note that this is still very, very incomplete! Contributions welcome!>

For each variable, there should be a description what it contains, when
it can be expected to exist (and contain meaningful information),
when it is sensible to define it yourself, and what effect this has.

Of course, the description may use examples.

=head2 PAR_0

If the running program is run from within a PAR archive or pp-produced
executable, this variable contains the name of the extracted program
(i.e. .pl file). This is useful of you want to open the source code
file of the running program.

For example, if you package a file F<foo.pl> into
F<bar.par> and run F<foo.pl> with this command

  par.pl foo.par bar.pl

then the C<PAR_0> variable will contain something like
C</tmp/par-youser/cache-b175f53eb731da9594e0dde337d66013ddf25a44/495829f0.pl>
where C<youser> is your username and
C</tmp/par-youser/cache-b175f53eb731da9594e0dde337d66013ddf25a44/> is the
PAR cache directory (C<PAR_TEMP>).

The name of the PAR cache directory can take a number of different forms,
so use C<PAR_0> if you want to find the extracted program's .pl file --
attempting to construct the name yourself requires complex logic that
has already produced the value in C<PAR_0>.

This works the same for executable binaries (F<.exe>, ...).

If you are looking for the name and path of the pp-ed binary file,
please refer to the C<PAR_PROGNAME> variable.

=head2 PAR_ARGC, PAR_ARGV_0, PAR_ARGV_...

You should not rely on these variables outside of the PAR binary loader
code.

These variables are set when a non-dependent pp-ed binary executable
runs. The initially executed process extracts another binary and runs
it as a child process. In order to pass its command line arguments to
the child, the parent process sets C<PAR_ARG*> as they would be
used in C programs: C<PAR_ARGC> has the number of arguments, C<PAR_ARGV_0>
has the name of the executable, C<PAR_ARGV_*> are the command line arguments.

If you would like to access the name of the running program (script or binary),
please refer to C<PAR_0> and C<PAR_PROGNAME> instead!

Related: C<PAR_SPAWNED>, C<PAR_0>, C<PAR_PROGNAME>

=head2 PAR_CLEAN

Users should set C<PAR_GLOBAL_CLEAN> instead.
Recreated from C<PAR_GLOBAL_CLEAN> and the value of C<-C> from the YAML file
by the PAR loader, and used within loader to control the initial behavior
of extraction, and the final behavior of cleanup.  The user can reference
C<PAR_CLEAN> in the application to determine which of these behaviors
is being used for this run of the application.

=head2 PAR_DEBUG

Users should set C<PAR_GLOBAL_DEBUG> instead.

If this variable is set to a true value and F<par.pl> is run,
verbose output is sent to STDOUT or the logging filehandle.
This is overridden by the C<-q> option to F<par.pl>,
for steps after argument parsing occurs.

This currently only influences F<par.pl>. Whether this is the intended
behaviour remains to be verified.

=head2 PAR_GLOBAL_CLEAN

Setting C<PAR_GLOBAL_CLEAN> alters the behavior of par applications
which see that environment variable at launch.
C<PAR_GLOBAL_CLEAN> overrides the C<-C> option.
Settings of 0 and 1 are supported.  0 corresponds to not using C<-C> on the
pp command line; 1 corresponds to using C<-C> on the pp command line.
C<PAR_GLOBAL_CLEAN> is ignored if C<PAR_GLOBAL_TEMP> is set, yet it
controls the form of C<PAR_TEMP> when C<PAR_GLOBAL_TEMP> is not set.

=head2 PAR_GLOBAL_DEBUG

The PAR loader becomes more verbose when C<PAR_DEBUG> is set.
Setting C<PAR_GLOBAL_DEBUG> guarantees that C<PAR_DEBUG> will be set
internally, initially.  See C<PAR_DEBUG> for more details.

=head2 PAR_GLOBAL_TEMP

Contributes to the calculation of C<PAR_TEMP>, and is further explained
there.

=head2 PAR_GLOBAL_TMPDIR

Contributes to the calculation of C<PAR_TEMP>, and is further explained
there.

=head2 PAR_INITIALIZED

This environment variable is for internal use by the PAR binary loader
only.
Documented only to avoid surprises if spawned applications expect
to see a value initialized by the user.

=head2 PAR_PROGNAME

C<PAR_PROGNAME> is set to the fully-qualified path name of the executable
program.
On Windows, this is reliably obtained from the C<GetModuleFileName> API.
On other OSes, if the C runtime is given a qualified path name, it is used,
or the unqualified file name given is qualified by walking the path.
This is reasonably reliable given normal program spawning conventions,
but cannot be guaranteed to be correct in all circumstances.

=head2 PAR_APP_REUSE

Strictly internal. Skip this section if you're not a PAR developer.

The variable shouldn't ever be exposed to user code and packaged
applications should not depend on it being set or not.

If an application has been packaged with the C<--reusable> option, the
bootstrapping code will set this environment variable to the name of
the program that is to be run instead of the packaged program.
The F<main.pl> loader script fetches the file name, deletes the
environment variable, and then runs the given program.

=head2 PAR_RUN

This environment variable was set during constructions of C<PAR::Packer>
objects (usually during F<pp> runs only) by versions of PAR up to
0.957. Since PAR 0.958, this variable is unused.

=head2 PAR_SPAWNED

This variable is used internally by the F<parl> binary loader to signal
the child process that it's the child.

You should not rely on this variable outside of the PAR binary loader
code. For a slightly more detailed discussion, please refer to the
F<who_am_i.txt> documentation file in the PAR source distribution
which was contributed by Alan Stewart. Related: C<PAR_ARGC>, C<PAR_ARGV_*>

Documented only to avoid surprises if spawned applications expect
to see a value initialized by the user.

=head2 PAR_TEMP

Users should set C<PAR_GLOBAL_TEMP> instead.
C<PAR_TEMP> is calculated from a variety of other variables.
See the C<NOTES> section in the pod for PAR.pm for
a complete description of how the calculation proceeds.
C<PAR_TEMP>, once calculated, is used as the location
where PAR stores its extracted, temporary file cache.

=head2 PAR_TMPDIR

Contributes to the calculation of C<PAR_TEMP>, and is further explained
there.  Users should set C<PAR_GLOBAL_TMPDIR> instead.

=head2 PAR_VERBATIM

The C<PAR_VERBATIM> variable controls the way Perl code is packaged
into a PAR archive or binary executable. If it is set to a true
value during the packaging process, modules (and scripts) are
B<not> passed through the default C<PAR::Filter::PodStrip> filter
which removes all POD documentation from the code. Note that the
C<PAR::Filter::PatchContent> filter is still applied.

The C<-F> option to the F<pp> tool overrides the C<PAR_VERBATIM>
setting. That means if you set C<PAR_VERBATIM=1> but specify
C<-F PodStrip> on the C<pp> command line, the C<PodStrip> filter
will be applied.

C<PAR_VERBATIM> is not used by the PAR application.

=head2 PAR_VERBOSE

Setting this environment variable to a positive integer
has the same effect as using the C<-verbose> switch to F<pp>.

=head2 PP_OPTS

During a F<pp> run, the contents of the C<PP_OPTS> variable are
treated as if they were part of the command line. In newer versions
of PAR, you can also write options to a file and execute F<pp>
as follows to read the options from the file:

  pp @FILENAME

That can, of course, be combined with other command line arguments
to F<pp> or the C<PP_OPTS> variable.

=head2 TMP, TEMP, TMPDIR, TEMPDIR

Please refer to C<PAR_TMPDIR>.

=head1 SEE ALSO

L<PAR>, L<PAR::Tutorial>, L<PAR::FAQ>

L<par.pl>, L<parl>, L<pp>

L<PAR::Dist> for details on PAR distributions.

=head1 AUTHORS

Steffen Mueller E<lt>smueller@cpan.orgE<gt>

You can write
to the mailing list at E<lt>par@perl.orgE<gt>, or send an empty mail to
E<lt>par-subscribe@perl.orgE<gt> to participate in the discussion.

Please submit bug reports to E<lt>bug-par@rt.cpan.orgE<gt>. If you need
support, however, joining the E<lt>par@perl.orgE<gt> mailing list is
preferred.

=head1 COPYRIGHT

PAR: Copyright 2003-2010 by Audrey Tang,
E<lt>cpan@audreyt.orgE<gt>.

This document: Copyright 2006-2010 by Steffen Mueller,
E<lt>smueller@cpan.orgE<gt>

Some information has been taken from Alan Stewart's extra documentation in the
F<contrib/> folder of the PAR distribution.

This program or documentation is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.

See F<LICENSE>.

=cut