perlfaq2.pod

ARM上的如果你对底层感兴趣

=head1 NAME

perlfaq2 - Obtaining and Learning about Perl ($Revision: 1.25 $, $Date: 1998/08/05 11:47:25 $)

=head1 DESCRIPTION

This section of the FAQ answers questions about where to find
source and documentation for Perl, support, and
related matters.

=head2 What machines support Perl?  Where do I get it?

The standard release of Perl (the one maintained by the perl
development team) is distributed only in source code form.  You
can find this at http://www.perl.com/CPAN/src/latest.tar.gz, which
in standard Internet format (a gzipped archive in POSIX tar format).

Perl builds and runs on a bewildering number of platforms.  Virtually
all known and current Unix derivatives are supported (Perl's native
platform), as are proprietary systems like VMS, DOS, OS/2, Windows,
QNX, BeOS, and the Amiga.  There are also the beginnings of support
for MPE/iX.

Binary distributions for some proprietary platforms, including
Apple systems can be found http://www.perl.com/CPAN/ports/ directory.
Because these are not part of the standard distribution, they may
and in fact do differ from the base Perl port in a variety of ways.
You'll have to check their respective release notes to see just
what the differences are.  These differences can be either positive
(e.g. extensions for the features of the particular platform that
are not supported in the source release of perl) or negative (e.g.
might be based upon a less current source release of perl).

A useful FAQ for Win32 Perl users is
http://www.endcontsw.com/people/evangelo/Perl_for_Win32_FAQ.html

=head2 How can I get a binary version of Perl?

If you don't have a C compiler because for whatever reasons your
vendor did not include one with your system, the best thing to do is
grab a binary version of gcc from the net and use that to compile perl
with.  CPAN only has binaries for systems that are terribly hard to
get free compilers for, not for Unix systems.

Your first stop should be http://www.perl.com/CPAN/ports to see what
information is already available.  A simple installation guide for
MS-DOS is available at http://www.cs.ruu.nl/~piet/perl5dos.html , and
similarly for Windows 3.1 at http://www.cs.ruu.nl/~piet/perlwin3.html
.

=head2 I don't have a C compiler on my system.  How can I compile perl?

Since you don't have a C compiler, you're doomed and your vendor
should be sacrificed to the Sun gods.  But that doesn't help you.

What you need to do is get a binary version of gcc for your system
first.  Consult the Usenet FAQs for your operating system for
information on where to get such a binary version.

=head2 I copied the Perl binary from one machine to another, but scripts don't work.

That's probably because you forgot libraries, or library paths differ.
You really should build the whole distribution on the machine it will
eventually live on, and then type C<make install>.  Most other
approaches are doomed to failure.

One simple way to check that things are in the right place is to print out
the hard-coded @INC which perl is looking for.

	perl -e 'print join("\n",@INC)'

If this command lists any paths which don't exist on your system, then you
may need to move the appropriate libraries to these locations, or create
symlinks, aliases, or shortcuts appropriately.

You might also want to check out L<perlfaq8/"How do I keep my own
module/library directory?">.

=head2 I grabbed the sources and tried to compile but gdbm/dynamic loading/malloc/linking/... failed.  How do I make it work?

Read the F<INSTALL> file, which is part of the source distribution.
It describes in detail how to cope with most idiosyncracies that the
Configure script can't work around for any given system or
architecture.

=head2 What modules and extensions are available for Perl?  What is CPAN?  What does CPAN/src/... mean?

CPAN stands for Comprehensive Perl Archive Network, a huge archive
replicated on dozens of machines all over the world.  CPAN contains
source code, non-native ports, documentation, scripts, and many
third-party modules and extensions, designed for everything from
commercial database interfaces to keyboard/screen control to web
walking and CGI scripts.  The master machine for CPAN is
ftp://ftp.funet.fi/pub/languages/perl/CPAN/, but you can use the
address http://www.perl.com/CPAN/CPAN.html to fetch a copy from a
"site near you".  See http://www.perl.com/CPAN (without a slash at the
end) for how this process works.

CPAN/path/... is a naming convention for files available on CPAN
sites.  CPAN indicates the base directory of a CPAN mirror, and the
rest of the path is the path from that directory to the file.  For
instance, if you're using ftp://ftp.funet.fi/pub/languages/perl/CPAN
as your CPAN site, the file CPAN/misc/japh file is downloadable as
ftp://ftp.funet.fi/pub/languages/perl/CPAN/misc/japh .

Considering that there are hundreds of existing modules in the
archive, one probably exists to do nearly anything you can think of.
Current categories under CPAN/modules/by-category/ include perl core
modules; development support; operating system interfaces; networking,
devices, and interprocess communication; data type utilities; database
interfaces; user interfaces; interfaces to other languages; filenames,
file systems, and file locking; internationalization and locale; world
wide web support; server and daemon utilities; archiving and
compression; image manipulation; mail and news; control flow
utilities; filehandle and I/O; Microsoft Windows modules; and
miscellaneous modules.

=head2 Is there an ISO or ANSI certified version of Perl?

Certainly not.  Larry expects that he'll be certified before Perl is.

=head2 Where can I get information on Perl?

The complete Perl documentation is available with the perl distribution.
If you have perl installed locally, you probably have the documentation
installed as well: type C<man perl> if you're on a system resembling Unix.
This will lead you to other important man pages, including how to set your
$MANPATH.  If you're not on a Unix system, access to the documentation
will be different; for example, it might be only in HTML format.  But all
proper perl installations have fully-accessible documentation.

You might also try C<perldoc perl> in case your system doesn't
have a proper man command, or it's been misinstalled.  If that doesn't
work, try looking in /usr/local/lib/perl5/pod for documentation.

If all else fails, consult the CPAN/doc directory, which contains the
complete documentation in various formats, including native pod,
troff, html, and plain text.  There's also a web page at
http://www.perl.com/perl/info/documentation.html that might help.

Many good books have been written about Perl -- see the section below
for more details.

=head2 What are the Perl newsgroups on USENET?  Where do I post questions?

The now defunct comp.lang.perl newsgroup has been superseded by the
following groups:

    comp.lang.perl.announce 		Moderated announcement group
    comp.lang.perl.misc     		Very busy group about Perl in general
    comp.lang.perl.moderated            Moderated discussion group
    comp.lang.perl.modules  		Use and development of Perl modules
    comp.lang.perl.tk           	Using Tk (and X) from Perl

    comp.infosystems.www.authoring.cgi 	Writing CGI scripts for the Web.

Actually, the moderated group hasn't passed yet, but we're
keeping our fingers crossed.

There is also USENET gateway to the mailing list used by the crack
Perl development team (perl5-porters) at
news://news.perl.com/perl.porters-gw/ .

=head2 Where should I post source code?

You should post source code to whichever group is most appropriate,
but feel free to cross-post to comp.lang.perl.misc.  If you want to
cross-post to alt.sources, please make sure it follows their posting
standards, including setting the Followup-To header line to NOT
include alt.sources; see their FAQ for details.

If you're just looking for software, first use Alta Vista, Deja News, and
search CPAN.  This is faster and more productive than just posting
a request.

=head2 Perl Books

A number of books on Perl and/or CGI programming are available.  A few of
these are good, some are ok, but many aren't worth your money.  Tom
Christiansen maintains a list of these books, some with extensive
reviews, at http://www.perl.com/perl/critiques/index.html.

The incontestably definitive reference book on Perl, written by
the creator of Perl, is now in its second edition:

    Programming Perl (the "Camel Book"):
	Authors: Larry Wall, Tom Christiansen, and Randal Schwartz
        ISBN 1-56592-149-6      (English)
        ISBN 4-89052-384-7      (Japanese)
	URL: http://www.oreilly.com/catalog/pperl2/
    (French, German, Italian, and Hungarian translations also
    available)

The companion volume to the Camel containing thousands
of real-world examples, mini-tutorials, and complete programs
(first premiering at the 1998 Perl Conference), is:

    The Perl Cookbook (the "Ram Book"):
	Authors: Tom Christiansen and Nathan Torkington, 
		    with Foreword by Larry Wall
	ISBN: 1-56592-243-3
	URL:  http://perl.oreilly.com/cookbook/

If you're already a hard-core systems programmer, then the Camel Book
might suffice for you to learn Perl from.  But if you're not, check
out:

    Learning Perl (the "Llama Book"):
	Authors: Randal Schwartz and Tom Christiansen 
		    with Foreword by Larry Wall
	ISBN: 1-56592-284-0
	URL:  http://www.oreilly.com/catalog/lperl2/

Despite the picture at the URL above, the second edition of "Llama
Book" really has a blue cover, and is updated for the 5.004 release
of Perl.  Various foreign language editions are available, including
I<Learning Perl on Win32 Systems> (the Gecko Book).

If you're not an accidental programmer, but a more serious and possibly
even degreed computer scientist who doesn't need as much hand-holding as
we try to provide in the Llama or its defurred cousin the Gecko, please
check out the delightful book, I<Perl: The Programmer's Companion>,
written by Nigel Chapman.

You can order O'Reilly books directly from O'Reilly & Associates,
1-800-998-9938.  Local/overseas is 1-707-829-0515.  If you can
locate an O'Reilly order form, you can also fax to 1-707-829-0104.
See http://www.ora.com/ on the Web.

What follows is a list of the books that the FAQ authors found personally
useful.  Your mileage may (but, we hope, probably won't) vary.

Recommended books on (or muchly on) Perl follow; those marked with
a star may be ordered from O'Reilly.

=over

=item References

    *Programming Perl
	by Larry Wall, Tom Christiansen, and Randal L. Schwartz

    *Perl 5 Desktop Reference
        By Johan Vromans

=item Tutorials
		
    *Learning Perl [2nd edition]
	by Randal L. Schwartz and Tom Christiansen
	    with foreword by Larry Wall