avoid reusing foreach itervar if magic got tacked onto it

[perl5.git] / README.vms

Last Revised 21-July-1998 by Dan Sugalski <sugalskd@ous.edu>
Originally by Charles Bailey <bailey@newman.upenn.edu>

* Important safety tip

The build and install procedures have changed significantly from the 5.004
releases! Make sure you read the "Building Perl" and "Installing Perl"
sections before you build or install.

Also note that, as of 5.005, an ANSI C compliant compiler is required to
build Perl. Vax C is *not* ANSI compliant, as it died a natural death some
time before the standard was set. Therefore Vax C will not compile perl
5.005. Sorry about that.

If you're stuck without Dec C (the Vax C license should be good for Dec C,
but the media charges might prohibit an upgrade), consider getting Gnu C
instead.

* Intro

The VMS port of Perl is as functionally complete as any other Perl port
(and as complete as the ports on some Unix systems). The Perl binaries
provide all the Perl system calls that are either available under VMS or
reasonably emulated. There are some incompatibilites in process handling
(e.g the fork/exec model for creating subprocesses doesn't do what you
might expect under Unix), mainly because VMS and Unix handle processes and
sub-processes very differently.

There are still some unimplemented system functions, and of coursse we
could use modules implementing useful VMS system services, so if you'd like
to lend a hand we'd love to have you. Join the Perl Porting Team Now!

The current sources and build procedures have been tested on a VAX using
VaxC and Dec C, and on an AXP using Dec C. If you run into problems with
other compilers, please let us know.

There are issues with varions versions of Dec C, so if you're not running a
relatively modern version, check the Dec C issues section later on in this
document.

* Other required software

In addition to VMS, you'll need:
        1) A C compiler. Dec C for AXP, or Dec C, or gcc for the VAX.
        2) A make tool. Dec's MMS (v2.6 or later), or MadGoat's free MMS
           analog MMK (available from ftp.madgoat.com/madgoat) both work
           just fine. Gnu Make might work, but it's been so long since
           anyone's tested it that we're not sure. MMK's free, though, so
           go ahead and use that.


If you want to include socket support, you'll need a TCP stack and either
Dec C, or socket libraries. See the Socket Support topic for more details.

* Building Perl

Building perl has two steps, configuration and compilation.

To configure perl (a necessary first step), issue the command

@CONFIGURE

from the top of an unpacked perl directory. You'll be asked a series of
questions, and the answers to them (along with the capabilities of your C
compiler and network stack) will determine how perl's built.

If you've got multiple C compilers installed, you'll have your choice of
which one to use. Various older versions of Dec C had some gotchas, so if
you're using a version older than 5.2, check the Dec C Issues section.

The configuration script will print out, at the very end, the MMS or MMK
command you need to compile perl. Issue it (exactly as printed) to start
the build.

Once you issue your MMS command, sit back and wait. Perl should build and
link without a problem. If it doesn't, check the Gotchas to watch out for
section. If that doesn't help, send some mail to the VMSPERL mailing list.
Instructions are in the Mailing Lists section.

As a handy shortcut, the command:

@CONFIGURE "-des"

(note the quotes and case) will choose reasonable defaults. (It takes Dec C
over Gnu C, Dec C sockets over SOCKETSHR sockets, and either over no sockets)

* Testing Perl

Once Perl has built cleanly, you need to test it to make sure things work.
This step is very important--there are always things that can go wrong
somehow and get you a dysfunctional Perl.

Testing is very easy, though, as there's a full test suite in the perl
distribution. To run the tests, enter the *exact* MMS line you used to
compile Perl and add the word "test" to the end, like this:

Compile Command:

$MMS/Macro=("__AXP__=1","decc=1","DECCRTL_SOCKETS=1")

Test Command:

$MMS/Macro=("__AXP__=1","decc=1","DECCRTL_SOCKETS=1") test

MMS will run all the tests. This may take some time, as there are a lot of
tests. If any tests fail, there will be a note made on-screen. At the end
of all the tests, a summary of the tests, the number passed and failed, and
the time taken will be displayed.

If any tests fail, it means something's wrong with Perl. If the test suite
hangs (some tests can take upwards of two or three minutes, or more if
you're on an especially slow machine, depending on you machine speed, so
don't be hasty), then the test *after* the last one displayed failed. Don't
install Perl unless you're confident that you're OK. Regardless of how
confident you are, make a bug report to the VMSPerl mailing list.

If one or more tests fail, you can get more info on the failure by issuing
this command sequence:

$ @[.VMS]TEST .typ "-v" [.subdir]test.T

where ".typ" is the file type of the Perl images you just built (if you
didn't do anything special, use .EXE), and "[.subdir]test.T" is the test
that failed. For example, with a normal Perl build, if the test indicated
that [.op]time failed, then you'd do this:

$ @[.VMS]TEST .EXE "-v" [.OP]TIME.T

When you send in a bug report for failed tests, please include the output
from this command, which is run from the main source directory:

MCR []MINIPERL "-V"

Note that "-V" really is a capital V in double quotes. This will dump out a
couple of screens worth of config info, and can help us diagnose the problem.

* Cleaning up and starting fresh

If you need to recompile from scratch, you have to make sure you clean up
first. There's a procedure to do it--enter the *exact* MMS line you used to
compile and add "realclean" at the end, like this:

Compile Command:

$MMS/Macro=("__AXP__=1","decc=1","DECCRTL_SOCKETS=1")

Cleanup Command:

$MMS/Macro=("__AXP__=1","decc=1","DECCRTL_SOCKETS=1") realclean

If you don't do this, things may behave erratically. They might not, too,
so it's best to be sure and do it.

* Installing Perl

There are several steps you need to take to get Perl installed and
running.

1) Create a directory somewhere and define the concealed logical PERL_ROOT
to point to it. For example, DEFINE/TRANS=(CONC,TERM) PERL_ROOT dka200:[perl.]

2) Run the install script via:

MMS install

or

MMK install

If for some reason it complains about target INSTALL being up to date,
throw a /FORCE switch on the MMS or MMK command.

3) Either define the symbol PERL somewhere, such as
SYS$MANAGER:SYLOGIN.COM, to be "PERL :== $PERL_ROOT:[000000]PERL.EXE", or
install Perl into DCLTABLES.EXE (Check out the section "Installing Perl
into DCLTABLES" for more info), or put the image in a directory that's in
your DCL$PATH (if you're using VMS 6.2 or higher).

4) Optionally define the command PERLDOC as 
PERLDOC :== "$PERL_ROOT:[000000]PERL PERL_ROOT:[LIB.POD]PERLDOC.COM -T"
Note that if you wish to use most as a pager please see
ftp://space.mit.edu/pub/davis/ for both most and slang.

5) Optionally define the command PERLBUG (the Perl bug report generator) as
PERLBUG :== "$PERL_ROOT:[000000]PERL PERL_ROOT:[LIB]PERLBUG.COM"

6) Optionally define the command POD2MAN (Converts POD files to nroff
source suitable for converting to man pages. Also quiets complaints during
module builds) as

DEFINE/NOLOG POD2MAN PERL_ROOT:[LIB.POD]POD2MAN.COM
POD2MAN :== "$PERL_ROOT:[000000]PERL POD2MAN"

7) Optionally define the command POD2TEXT (Converts POD files to text,
which is required for perldoc -f to work properly) as

DEFINE/NOLOG POD2TEXT PERL_ROOT:[LIB.POD]POD2TEXT.COM
POD2TEXT :== "$PERL_ROOT:[000000]PERL POD2TEXT"

In all these cases, if you've got PERL defined as a foreign command, you
can replace $PERL_ROOT:[000000]PERL with ''perl'. If you've installed perl
into DCLTABLES, replace it with just perl.

* Installing Perl into DCLTABLES

Execute the following command file to define PERL as a DCL command.
You'll need CMKRNL priv to install the new dcltables.exe.

$ create perl.cld
!
! modify to reflect location of your perl.exe
!
define verb perl
  image perl_root:[000000]perl.exe
  cliflags (foreign)
$!
$ set command perl /table=sys$common:[syslib]dcltables.exe -
 /output=sys$common:[syslib]dcltables.exe
$ install replace sys$common:[syslib]dcltables.exe
$ exit

* Changing compile-time things

Most of the user-definable features of Perl are enabled or disabled in
[.VMS]CONFIG.VMS. There's code in there to Do The Right Thing, but that may
end up being the wrong thing for you. Make sure you understand what you're
doing, since changes here can get you a busted perl.

Odds are that there's nothing here to change, unless you're on a version of
VMS later than 6.2 and Dec C later than 5.6. Even if you are, the correct
values will still be chosen, most likely. Poking around here should be
unnecessary.

The one exception is the various *DIR install locations. Changing those
requires changes in genconfig.pl as well. Be really careful if you need to
change these,a s they can cause some fairly subtle problems.

* Extra things in the Perl distribution

In addition to the standard stuff that gets installed, there are two
optional extensions, DCLSYM and STDIO, that are handy. Instructions for
these two modules are in [.VMS.EXT.DCLSYM] and [.VMS.EXT.STDIO],
respectively.

* Socket Support

Perl includes a number of functions for IP sockets, which are available if
you choose to compile Perl with socket support. (See the section Compiling
Perl for more info on selecting a socket stack) Since IP networking is an
optional addition to VMS, there are several different IP stacks
available. How well integrated they are into the system depends on the
stack, your version of VMS, and the version of your C compiler.

The most portable solution uses the SOCKETSHR library. In combination with
either UCX or NetLib, this supports all the major TCP stacks (Multinet,
Pathways, TCPWare, UCX, and CMU) on all versions of VMS Perl runs on, with
all the compilers on both VAX and Alpha. The socket interface is also
consistent across versions of VMS and C compilers. It has a problem with
UDP sockets when used with Multinet, though, so you should be aware of
that.

The other solution available is to use the socket routines built into Dec
C. Which routines are available depend on the version of VMS you're
running, and require proper UCX emulation by your TCP/IP vendor.
Relatively current versions of Multinet, TCPWare, Pathway, and UCX all
provide the required libraries--check your manuals or release notes to see
if your version is new enough.

* Reporting Bugs

If you come across what you think might be a bug in Perl, please report
it. There's a script in PERL_ROOT:[UTILS], perlbug, that walks you through
the process of creating a bug report. This script includes details of your
installation, and is very handy. Completed bug reports should go to
PERLBUG@PERL.COM.

* Gotchas to watch out for

Probably the single biggest gotcha in compiling Perl is giving the wrong
switches to MMS/MMK when you build. Use *exactly* what the configure script
prints!

The next big gotcha is directory depth. Perl can create directories four
and five levels deep during the build, so you don't have to be too deep to
start to hit the RMS 8 level point. It's best to do a
$DEFINE/TRANS=(CONC,TERM) PERLSRC disk:[dir.dir.dir.perldir.]"  (note the
trailing period) and $SET DEFAULT PERLSRC:[000000] before building. Perl
modules can be just as bad (or worse), so watch out for them, too. The
configuration script will warn if it thinks you're too deep.

Finally, the third thing that bites people is leftover pieces from a failed
build. If things go wrong, make sure you do a "(MMK|MMS|make) realclean"
before you rebuild.

* Dec C issues

Note to DECC users: Some early versions (pre-5.2, some pre-4. If you're Dec
C 5.x or higher, with current patches if anym you're fine) of the DECCRTL
contained a few bugs which affect Perl performance:
    - Newlines are lost on I/O through pipes, causing lines to run together.
      This shows up as RMS RTB errors when reading from a pipe.  You can
      work around this by having one process write data to a file, and
      then having the other read the file, instead of the pipe.  This is
      fixed in version 4 of DECC.
    - The modf() routine returns a non-integral value for some values above
      INT_MAX; the Perl "int" operator will return a non-integral value in
      these cases.  This is fixed in version 4 of DECC.
    - On the AXP, if SYSNAM privilege is enabled, the CRTL chdir() routine
      changes the process default device and directory permanently, even
      though the call specified that the change should not persist after
      Perl exited.  This is fixed by DEC CSC patch AXPACRT04_061.

* Mailing Lists

There are several mailing lists available to the Perl porter. For VMS
specific issues (including both Perl questions and installation problems)
there is the VMSPERL mailing list. It's usually a low-volume (10-12
messages a week) mailing list.

The subscription address is VMSPERL-REQUEST@NEWMAN.UPENN.EDU. Send a mail
message with just the words SUBSCRIBE VMSPERL in the body of the message.

The VMSPERL mailing list address is VMSPERL@NEWMAN.UPENN.EDU. Any mail
sent there gets echoed to all subscribers of the list.

The Perl5-Porters list is for anyone involved in porting Perl to a
platform. This includes you, if you want to participate. It's a high-volume
list (60-100 messages a day during active development times), so be sure
you want to be there. The subscription address is
Perl5-Porters-request@perl.org. Send a message with just the word SUBSCRIBE
in the body. The posting address is Perl5-Porters@perl.org.

* Acknowledgements

A real big thanks needs to go to Charles Bailey
<bailey@newman.upenn.edu>, who is ultimately responsible for Perl 5.004
running on VMS. Without him, nothing the rest of us have done would be at
all important.

There are, of course, far too many people involved in the porting and testing
of Perl to mention everyone who deserves it, so please forgive us if we've
missed someone.  That said, special thanks are due to the following:
  Tim Adye <T.J.Adye@rl.ac.uk>
     for the VMS emulations of getpw*()
  David Denholm <denholm@conmat.phys.soton.ac.uk>
     for extensive testing and provision of pipe and SocketShr code,
  Mark Pizzolato <mark@infocomm.com>
     for the getredirection() code
  Rich Salz <rsalz@bbn.com>
     for readdir() and related routines
  Peter Prymmer <pvhp@lns62.lns.cornell.edu)
     for extensive testing, as well as development work on
     configuration and documentation for VMS Perl,
  Dan Sugalski <sugalsd@stargate.lbcc.cc.or.us>
     for extensive contributions to recent version support,
     development of VMS-specific extensions, and dissemination
     of information about VMS Perl,
  the Stanford Synchrotron Radiation Laboratory and the
     Laboratory of Nuclear Studies at Cornell University for
     the the opportunity to test and develop for the AXP,
and to the entire VMSperl group for useful advice and suggestions.  In
addition the perl5-porters deserve credit for their creativity and
willingness to work with the VMS newcomers.  Finally, the greatest debt of
gratitude is due to Larry Wall <larry@wall.org>, for having the ideas which
have made our sleepless nights possible.

Thanks,
The VMSperl group