Warn on 'undef $x; $x OP 1' where OP is *=, /=, %=, or **=

[perl5.git] / INSTALL

=head1 NAME

Install - Build and Installation guide for perl5.

=head1 SYNOPSIS

The basic steps to build and install perl5 on a Unix system are:

	rm -f config.sh
	sh Configure
	make
	make test
	make install
	# possibly add these:
	(cd /usr/include  && h2ph *.h sys/*.h)
	cd pod; make html && mv *.html <www home dir>  && cd ..
	cd pod; make tex  && <process the latex files> && cd ..


Each of these is explained in further detail below.

For information on non-Unix systems, see the section on
L<"Porting Information">, below.

=head1 DESCRIPTION

You should probably at least skim through this entire document before
proceeding.  Special notes specific to this release are identified
by B<NOTE>.

This document is written in pod format as an easy way to indicate its
structure.  The pod format is described in pod/perlpod.pod, but you can
read it as is with any pager or editor.

If you're building Perl on a non-Unix system, you should also read
the README file specific to your operating system, since this may
provide additional or different instructions for building Perl.

=head1 Space Requirements.

The complete perl5 source tree takes up about 7 MB of disk space.
The complete tree after completing C<make> takes roughly
15 MB, though the actual total is likely to be quite
system-dependent.  The installation directories need something
on the order of 7 MB, though again that value is system-dependent.

=head1 Start with a Fresh Distribution.

If you have built perl before, you should clean out the build directory
with the command

	make realclean

The results of a Configure run are stored in the config.sh file.  If
you are upgrading from a previous version of perl, or if you change
systems or compilers or make other significant changes, or if you are
experiencing difficulties building perl, you should probably I<not>
re-use your old config.sh.  Simply remove it or rename it, e.g.

	mv config.sh config.sh.old

If you wish to use your old config.sh, be especially attentive to the
version and architecture-specific questions and answers.  For example,
the default directory for architecture-dependent library modules
includes the version name.  By default, Configure will reuse your old
name (e.g. /opt/perl/lib/i86pc-solaris/5.003) even if you're running
Configure for a different version, e.g. 5.004.  Yes, Configure should
probably check and correct for this, but it doesn't, presently.
Similarly, if you used a shared libperl.so (see below) with version
numbers, you will probably want to adjust them as well.

Also, be careful to check your architecture name.  Some Linux systems
call themselves i486, while others use i586.  If you pick up a
precompiled binary, it might not use the same name.

In short, if you wish to use your old config.sh, I recommend running
Configure interactively rather than blindly accepting the defaults.

=head1 Run Configure.

Configure will figure out various things about your system.  Some
things Configure will figure out for itself, other things it will ask
you about.  To accept the default, just press C<RETURN>.   The default
is almost always ok.

After it runs, Configure will perform variable substitution on all the
F<*.SH> files and offer to run B<make depend>.

Configure supports a number of useful options.  Run B<Configure -h>
to get a listing.  To compile with gcc, for example, you can run

	sh Configure -Dcc=gcc

This is the preferred way to specify gcc (or another alternative
compiler) so that the hints files can set appropriate defaults.

If you want to use your old config.sh but override some of the items
with command line options, you need to use B<Configure -O>.

If you are willing to accept all the defaults, and you want terse
output, you can run

	sh Configure -des

By default, for most systems, perl will be installed in
/usr/local/{bin, lib, man}.  You can specify a different 'prefix' for
the default installation directory, when Configure prompts you or by
using the Configure command line option -Dprefix='/some/directory',
e.g.

	sh Configure -Dprefix=/opt/perl

If your prefix contains the string "perl", then the directories
are simplified.  For example, if you use prefix=/opt/perl,
then Configure will suggest /opt/perl/lib instead of
/usr/local/lib/perl5/.

By default, Configure will compile perl to use dynamic loading, if
your system supports it.  If you want to force perl to be compiled
statically, you can either choose this when Configure prompts you or
you can use the Configure command line option -Uusedl.

=head2 Extensions

By default, Configure will offer to build every extension which appears
to be supported.  For example, Configure will offer to build GDBM_File
only if it is able to find the gdbm library.  (See examples below.)
DynaLoader, Fcntl, and IO are always built by default.  Configure does
not contain code to test for POSIX compliance, so POSIX is always built
by default as well.  If you wish to skip POSIX, you can set the
Configure variable useposix=false either in a hint file or from the
Configure command line.  Similarly, the Opcode extension is always built
by default, but you can skip it by setting the Configure variable
useopcode=false either in a hint file for from the command line.

Even if you do not have dynamic loading, you must still build the
DynaLoader extension; you should just build the stub dl_none.xs
version.  (Configure will suggest this as the default.)

In summary, here are the Configure command-line variables you can set
to turn off each extension:

    DB_File		i_db
    DynaLoader		(Must always be included as a static extension)
    Fcntl		(Always included by default)
    GDBM_File		i_gdbm
    IO			(Always included by default)
    NDBM_File		i_ndbm
    ODBM_File		i_dbm
    POSIX		useposix
    SDBM_File		(Always included by default)
    Opcode		useopcode
    Socket		d_socket

Thus to skip the NDBM_File extension, you can use

	sh Configure -Ui_ndbm

Again, this is taken care of automatically if you don't have the ndbm
library.

Of course, you may always run Configure interactively and select only
the Extensions you want.

Finally, if you have dynamic loading (most modern Unix systems do)
remember that these extensions do not increase the size of your perl
executable, nor do they impact start-up time, so you probably might as
well build all the ones that will work on your system.

=head2 GNU-style configure

If you prefer the GNU-style B<configure> command line interface, you can
use the supplied B<configure> command, e.g.

	CC=gcc ./configure

The B<configure> script emulates several of the more common configure
options.  Try

	./configure --help

for a listing.

Cross compiling is currently not supported.

=head2 Including locally-installed libraries

Perl5 comes with interfaces to number of database extensions, including
dbm, ndbm, gdbm, and Berkeley db.  For each extension, if
Configure can find the appropriate header files and libraries, it will
automatically include that extension.  The gdbm and db libraries
are B<not> included with perl.  See the library documentation for
how to obtain the libraries.

I<Note:>  If your database header (.h) files are not in a
directory normally searched by your C compiler, then you will need to
include the appropriate B<-I/your/directory> option when prompted by
Configure.  If your database library (.a) files are not in a directory
normally searched by your C compiler and linker, then you will need to
include the appropriate B<-L/your/directory> option when prompted by
Configure.  See the examples below.

=head2 Examples

=over 4

=item gdbm in /usr/local.

Suppose you have gdbm and want Configure to find it and build the
GDBM_File extension.  This examples assumes you have F<gdbm.h>
installed in F</usr/local/include/gdbm.h> and F<libgdbm.a> installed in
F</usr/local/lib/libgdbm.a>.  Configure should figure all the
necessary steps out automatically.

Specifically, when Configure prompts you for flags for
your C compiler, you should include  C<-I/usr/local/include>.

When Configure prompts you for linker flags, you should include
C<-L/usr/local/lib>.

If you are using dynamic loading, then when Configure prompts you for
linker flags for dynamic loading, you should again include
C<-L/usr/local/lib>.

Again, this should all happen automatically.  If you want to accept the
defaults for all the questions and have Configure print out only terse
messages, then you can just run

	sh Configure -des

and Configure should include the GDBM_File extension automatically.

This should actually work if you have gdbm installed in any of
(/usr/local, /opt/local, /usr/gnu, /opt/gnu, /usr/GNU, or /opt/GNU).

=item gdbm in /usr/you

Suppose you have gdbm installed in some place other than /usr/local/,
but you still want Configure to find it.  To be specific, assume  you
have F</usr/you/include/gdbm.h> and F</usr/you/lib/libgdbm.a>.  You
still have to add B<-I/usr/you/include> to cc flags, but you have to take
an extra step to help Configure find F<libgdbm.a>.  Specifically, when
Configure prompts you for library directories, you have to add
F</usr/you/lib> to the list.

It is possible to specify this from the command line too (all on one
line):

	sh Configure -des \
		-Dlocincpth="/usr/you/include" \
		-Dloclibpth="/usr/you/lib"

C<locincpth> is a space-separated list of include directories to search.
Configure will automatically add the appropriate B<-I> directives.

C<loclibpth> is a space-separated list of library directories to search.
Configure will automatically add the appropriate B<-L> directives.  If
you have some libraries under F</usr/local/> and others under
F</usr/you>, then you have to include both, namely

	sh Configure -des \
		-Dlocincpth="/usr/you/include /usr/local/include" \
		-Dloclibpth="/usr/you/lib /usr/local/lib"

=back

=head2 Installation Directories.

The installation directories can all be changed by answering the
appropriate questions in Configure.  For convenience, all the
installation questions are near the beginning of Configure.

By default, Configure uses the following directories for
library files  (archname is a string like sun4-sunos, determined
by Configure)

	/usr/local/lib/perl5/archname/5.002
	/usr/local/lib/perl5/
	/usr/local/lib/perl5/site_perl/archname
	/usr/local/lib/perl5/site_perl

and the following directories for manual pages:

	/usr/local/man/man1
	/usr/local/lib/perl5/man/man3

(Actually, Configure recognizes the SVR3-style
/usr/local/man/l_man/man1 directories, if present, and uses those
instead.) The module man pages are stuck in that strange spot so that
they don't collide with other man pages stored in /usr/local/man/man3,
and so that Perl's man pages don't hide system man pages.  On some
systems, B<man less> would end up calling up Perl's less.pm module man
page, rather than the B<less> program.

If you specify a prefix that contains the string "perl", then the
directory structure is simplified.  For example, if you Configure
with -Dprefix=/opt/perl, then the defaults are

	/opt/perl/lib/archname/5.002
	/opt/perl/lib
	/opt/perl/lib/site_perl/archname
	/opt/perl/lib/site_perl

	/opt/perl/man/man1
	/opt/perl/man/man3

The perl executable will search the libraries in the order given
above.

The  directories site_perl and site_perl/archname are empty, but are
intended to be used for installing local or site-wide extensions.  Perl
will automatically look in these directories.  Previously, most sites
just put their local extensions in with the standard distribution.

In order to support using things like #!/usr/local/bin/perl5.002 after
a later version is released, architecture-dependent libraries are
stored in a version-specific directory, such as
/usr/local/lib/perl5/archname/5.002/.  In 5.000 and 5.001, these files
were just stored in /usr/local/lib/perl5/archname/.  If you will not be
using 5.001 binaries, you can delete the standard extensions from the
/usr/local/lib/perl5/archname/ directory.  Locally-added extensions can
be moved to the site_perl and site_perl/archname directories.

Again, these are just the defaults, and can be changed as you run
Configure.

=head2 Changing the installation directory

Configure distinguishes between the directory in which perl (and its
associated files) should be installed and the directory in which it
will eventually reside.  For most sites, these two are the same; for
sites that use AFS, this distinction is handled automatically.
However, sites that use software such as B<depot> to manage software
packages may also wish to install perl into a different directory and
use that management software to move perl to its final destination.
This section describes how to do this.  Someday, Configure may support
an option C<-Dinstallprefix=/foo> to simplify this.

Suppose you want to install perl under the F</tmp/perl5> directory.
You can edit F<config.sh> and change all the install* variables to
point to F</tmp/perl5> instead of F</usr/local/wherever>.  You could
also set them all from the Configure command line.  Or, you can
automate this process by placing the following lines in a file
F<config.over> B<before> you run Configure (replace /tmp/perl5 by a
directory of your choice):

    installprefix=/tmp/perl5
    test -d $installprefix || mkdir $installprefix
    test -d $installprefix/bin || mkdir $installprefix/bin
    installarchlib=`echo $installarchlib | sed "s!$prefix!$installprefix!"`
    installbin=`echo $installbin | sed "s!$prefix!$installprefix!"`
    installman1dir=`echo $installman1dir | sed "s!$prefix!$installprefix!"`
    installman3dir=`echo $installman3dir | sed "s!$prefix!$installprefix!"`
    installprivlib=`echo $installprivlib | sed "s!$prefix!$installprefix!"`
    installscript=`echo $installscript | sed "s!$prefix!$installprefix!"`
    installsitelib=`echo $installsitelib | sed "s!$prefix!$installprefix!"`
    installsitearch=`echo $installsitearch | sed "s!$prefix!$installprefix!"`

Then, you can Configure and install in the usual way:

    sh Configure -des
    make
    make test
    make install

=head2 Creating an installable tar archive

If you need to install perl on many identical systems, it is
convenient to compile it once and create an archive that can be
installed on multiple systems.  Here's one way to do that:

    # Set up config.over to install perl into a different directory,
    # e.g. /tmp/perl5 (see previous part).
    sh Configure -des
    make
    make test
    make install
    cd /tmp/perl5
    tar cvf ../perl5-archive.tar .
    # Then, on each machine where you want to install perl,
    cd /usr/local  # Or wherever you specified as $prefix
    tar xvf perl5-archive.tar

=head2 Building a shared libperl.so Perl library.

Currently, for most systems, the main perl executable is built by
linking the "perl library" libperl.a with perlmain.o, your static
extensions (usually just DynaLoader.a) and various extra libraries,
such as -lm.

On some systems that support dynamic loading, it may be possible to
replace libperl.a with a shared libperl.so.  If you anticipate building
several different perl binaries (e.g. by embedding libperl into
different programs, or by using the optional compiler extension), then
you might wish to build a shared libperl.so so that all your binaries
can share the same library.

The disadvantages are that there may be a significant performance
penalty associated with the shared libperl.so, and that the overall
meachanism is still rather fragile with respect to different versions
and upgrades.

In terms of performance, on my test system (Solaris 2.5_x86) the perl
test suite took roughly 15% longer to run with the shared libperl.so.
Your system and typical applications may well give quite different
results.

The default name for the shared library is typically something like
libperl.so.3.2 (for perl5.003_02) or libperl.so.302 or simply
libperl.so.  Configure tries to guess a sensible naming convention
based on your C library name.  Since the library gets installed in a
version-specific architecture-dependent directory, the exact name
isn't very important anyway, as long as your linker is happy.

For some systems (mostly SVR4), building a shared libperl is required
for dynamic loading to work, and hence is already the default.

You can elect to build a shared libperl by

	sh Configure -Duseshrplib

To actually build perl, you must add the current working directory to your
LD_LIBRARY_PATH environtment variable before running make.  You can do
this with

   LD_LIBRARY_PATH=`pwd`:$LD_LIBRARY_PATH; export LD_LIBRARY_PATH

for Bourne-style shells, or

   setenv LD_LIBRARY_PATH `pwd`

for Csh-style shells.  You *MUST* do this before running make.
Folks running NeXT OPENSTEP must substitute DYLD_LIBRARY_PATH for
LD_LIBRARY_PATH above.

There is also an potential problem with the shared perl library if you
want to have more than one "flavor" of the same version of perl (e.g.
with and without -DDEBUGGING).  For example, suppose you build and
install a standard perl5.004 with a shared library.  Then, suppose you
try to build perl5.004 with -DDEBUGGING enabled, but everything else
the same, including all the installation directories.  How can you
ensure that your newly built perl will link with your newly built
libperl.so.4 rather with the installed libperl.so.4?  The answer is
that you might not be able to.  The installation directory is encoded
in the perl binary with the LD_RUN_PATH environment variable (or
equivalent ld command-line option).  On Solaris, you can override that
with LD_LIBRARY_PATH; on Linux you can't.

The only reliable answer is that you should specify a different
directory for the architecture-dependent library for your -DDEBUGGING
version of perl.  You can do this with by changing all the *archlib*
variables in config.sh, namely archlib, archlib_exp, and
installarchlib, to point to your new architecture-dependent library.

=head2 Selecting File IO mechanisms

Previous versions of perl used the standard IO mechanisms as defined in
<stdio.h>.  Versions 5.003_02 and later of perl allow alternate IO
mechanisms via a "PerlIO" abstraction, but the stdio mechanism is still
the default and is the only supported mechanism.

This PerlIO abstraction can be enabled either on the Configure command
line with

	sh Configure -Duseperlio

or interactively at the appropriate Configure prompt.

If you choose to use the PerlIO abstraction layer, there are two
(experimental) possibilities for the underlying IO calls.  These have been
tested to some extent on some platforms, but are not guaranteed to work
everywhere.

=over 4

=item 1.

AT&T's "sfio".  This has superior performance to <stdio.h> in many
cases, and is extensible by the use of "disipline" modules.  Sfio
currently only builds on a subset of the UNIX platforms perl supports.
Because the data structures are completely different from stdio, perl
extension modules or external libraries may not work.  This
configuration exists to allow these issues to be worked on.

This option requires the 'sfio' package to have been built and installed.
A (fairly old) version of sfio is in CPAN, and work is in progress to make
it more easily buildable by adding Configure support.

You select this option by

	sh Configure -Duseperlio -Dusesfio

If you have already selected -Duseperlio, and if Configure detects
that you have sfio, then sfio will be the default suggested by
Configure.

=item 2.

Normal stdio IO, but with all IO going through calls to the PerlIO
abstraction layer.  This configuration can be used to check that perl and
extension modules have been correctly converted to use the PerlIO
abstraction.

This configuration should work on all platforms (but might not).

You select this option via :

	sh Configure -Duseperlio -Uusesfio

If you have already selected -Duseperlio, and if Configure does not
detect sfio, then this will be the default suggested by Configure.

=back

=head2 What if it doesn't work?

=over 4

=item Running Configure Interactively

If Configure runs into trouble, remember that you can always run
Configure interactively so that you can check (and correct) its
guesses.

All the installation questions have been moved to the top, so you don't
have to wait for them.  Once you've handled them (and your C compiler &
flags) you can type   C<&-d>  at the next Configure prompt and Configure
will use the defaults from then on.

If you find yourself trying obscure command line incantations and
config.over tricks, I recommend you run Configure interactively
instead.  You'll probably save yourself time in the long run.

=item Hint files.

The perl distribution includes a number of system-specific hints files
in the hints/ directory.  If one of them matches your system, Configure
will offer to use that hint file.

Several of the hint files contain additional important information.
If you have any problems, it is a good idea to read the relevant hint
file for further information.  See F<hints/solaris_2.sh> for an
extensive example.

=item *** WHOA THERE!!! ***

Occasionally, Configure makes a wrong guess.  For example, on SunOS
4.1.3, Configure incorrectly concludes that tzname[] is in the
standard C library.  The hint file is set up to correct for this.  You
will see a message:

    *** WHOA THERE!!! ***
	The recommended value for $d_tzname on this machine was "undef"!
	Keep the recommended value? [y]

You should always keep the recommended value unless, after reading the
relevant section of the hint file, you are sure you want to try
overriding it.

If you are re-using an old config.sh, the word "previous" will be
used instead of "recommended".  Again, you will almost always want
to keep the previous value, unless you have changed something on your
system.

For example, suppose you have added libgdbm.a to your system
and you decide to reconfigure perl to use GDBM_File.  When you run
Configure again, you will need to add -lgdbm to the list of libraries.
Now, Configure will find your gdbm library and will issue a message:

    *** WHOA THERE!!! ***
	The previous value for $i_gdbm on this machine was "undef"!
	Keep the previous value? [y]

In this case, you do I<not> want to keep the previous value, so you
should answer 'n'.  (You'll also have to manually add GDBM_File to
the list of dynamic extensions to build.)

=item Changing Compilers

If you change compilers or make other significant changes, you should
probably I<not> re-use your old config.sh.  Simply remove it or
rename it, e.g. mv config.sh config.sh.old.  Then rerun Configure
with the options you want to use.

This is a common source of problems.  If you change from B<cc> to
B<gcc>, you should almost always remove your old config.sh.

=item Propagating your changes to config.sh

If you make any changes to F<config.sh>, you should propagate
them to all the .SH files by running  B<sh Configure -S>.  You will
then have to rebuild by running

	make depend
	make

=item config.over

You can also supply a shell script config.over to over-ride Configure's
guesses.  It will get loaded up at the very end, just before config.sh
is created.  You have to be careful with this, however, as Configure
does no checking that your changes make sense.  See the section on
L<"Changing the installation directory"> for an example.

=item config.h

Many of the system dependencies are contained in F<config.h>.
F<Configure> builds F<config.h> by running the F<config_h.SH> script.
The values for the variables are taken from F<config.sh>.

If there are any problems, you can edit F<config.h> directly.  Beware,
though, that the next time you run B<Configure>, your changes will be
lost.

=item cflags

If you have any additional changes to make to the C compiler command
line, they can be made in F<cflags.SH>.  For instance, to turn off the
optimizer on F<toke.c>, find the line in the switch structure for
F<toke.c> and put the command C<optimize='-g'> before the C<;;>.  You
can also edit F<cflags> directly, but beware that your changes will be
lost the next time you run B<Configure>.

To change the C flags for all the files, edit F<config.sh>
and change either C<$ccflags> or C<$optimize>,
and then re-run  B<sh Configure -S ; make depend>.

=item No sh.

If you don't have sh, you'll have to copy the sample file config_H to
config.h and edit the config.h to reflect your system's peculiarities.
You'll probably also have to extensively modify the extension building
mechanism.

=item Porting information

Specific information for the OS/2, Plan9, and VMS ports are in the
corresponing subdirectories.  Additional information, including
a glossary of all those config.sh variables, is in the Porting
subdirectory.

Ports for other systems may also be available.  You should check out
L<"http:/www.perl.com/CPAN/ports"> for current information on ports to
various other operating systems.

=back

=head1 Binary Compatibility With 5.003

Perl 5.003 turned on the EMBED feature by default, which tries to
avoid possible symbol name conflict by prefixing all global symbols
with "Perl_".  However, its list of global symbols was incomplete.
This error has been rectified in Perl 5.004.

However, some sites may need to maintain complete binary compatibility
with Perl 5.003.  If you are building Perl for such a site, then when
B<Configure> asks if you want binary compatibility, answer "y".

=head1 make depend

This will look for all the includes.
The output is stored in F<makefile>.  The only difference between
F<Makefile> and F<makefile> is the dependencies at the bottom of
F<makefile>.  If you have to make any changes, you should edit
F<makefile>, not F<Makefile> since the Unix B<make> command reads
F<makefile> first.  (On non-Unix systems, the output may be stored in
a different file.  Check the value of $firstmakefile in your config.sh
if in doubt.)

Configure will offer to do this step for you, so it isn't listed
explicitly above.

=head1 make

This will attempt to make perl in the current directory.

If you can't compile successfully, try some of the following ideas.
If none of them help, and careful reading of the error message and
the relevant manual pages on your system doesn't help, you can
send a message to either the comp.lang.perl.misc newsgroup or to
perlbug@perl.com with an accurate description of your problem.
Please include the I<output> of the B<./myconfig> shell script
that comes with the distribution.

[The B<perlbug> program that comes with the perl distribution is
useful for sending in such reports, but you need to have
perl compiled and installed before you can use it.]

=over 4

=item *

If you used a hint file, try reading the comments in the hint file
for further tips and information.

=item *

If you can successfully build F<miniperl>, but the process crashes
during the building of extensions, you should run

    	make minitest

to test your version of miniperl.

=item locale

If you have any locale-related environment variables set, try
unsetting them.  I have some reports that some versions of IRIX hang
while running B<./miniperl configpm> with locales other than the C
locale.  See the discussion under L<make test> below about locales.

=item *

If you get duplicates upon linking for malloc et al, say -DHIDEMYMALLOC.

=item varargs

If you get varargs problems with gcc, be sure that gcc is installed
correctly.  When using gcc, you should probably have i_stdarg='define'
and i_varargs='undef' in config.sh.  The problem is usually solved by
running fixincludes correctly.  If you do change config.sh, don't
forget to propagate your changes (see
L<"Propagating your changes to config.sh"> below).
See also the L<"vsprintf"> item below.

=item *

If you get error messages such as the following (the exact line
numbers will vary in different versions of perl):

    util.c: In function `Perl_croak':
    util.c:962: number of arguments doesn't match prototype
    proto.h:45: prototype declaration

it might well be a symptom of the gcc "varargs problem".  See the
previous L<"varargs"> item.

=item Solaris and SunOS dynamic loading

If you have problems with dynamic loading using gcc on SunOS or
Solaris, and you are using GNU as and GNU ld, you may need to add
B<-B/bin/> (for SunOS) or B<-B/usr/ccs/bin/> (for Solaris) to your
$ccflags, $ldflags, and $lddlflags so that the system's versions of as
and ld are used.  Alternatively, you can use the GCC_EXEC_PREFIX
environment variable to ensure that Sun's as and ld are used.  Consult
your gcc documentation for further information on the B<-B> option and
the GCC_EXEC_PREFIX variable.

=item ld.so.1: ./perl: fatal: relocation error:

If you get this message on SunOS or Solaris, and you're using gcc,
it's probably the GNU as or GNU ld problem in the previous item
L<"Solaris and SunOS dynamic loading">.

=item *

If you run into dynamic loading problems, check your setting of
the LD_LIBRARY_PATH environment variable.  Perl should build
fine with LD_LIBRARY_PATH unset, though that may depend on details
of your local set-up.

=item dlopen: stub interception failed

The primary cause of the 'dlopen: stub interception failed' message is
that the LD_LIBRARY_PATH environment variable includes a directory
which is a symlink to /usr/lib (such as /lib).

The reason this causes a problem is quite subtle. The file libdl.so.1.0
actually *only* contains functions which generate 'stub interception
failed' errors!  The runtime linker intercepts links to
"/usr/lib/libdl.so.1.0" and links in internal implementation of those
functions instead.  [Thanks to Tim Bunce for this explanation.]

=item *

If Configure seems to be having trouble finding library functions,
try not using nm extraction.  You can do this from the command line
with

	sh Configure -Uusenm

or by answering the nm extraction question interactively.
If you have previously run Configure, you should I<not> reuse your old
config.sh.

=item vsprintf

If you run into problems with vsprintf in compiling util.c, the
problem is probably that Configure failed to detect your system's
version of vsprintf().  Check whether your system has vprintf().
(Virtually all modern Unix systems do.)  Then, check the variable
d_vprintf in config.sh.  If your system has vprintf, it should be:

	d_vprintf='define'

If Configure guessed wrong, it is likely that Configure guessed wrong
on a number of other common functions too.  You are probably better off
re-running Configure without using nm extraction (see previous item).

=item *

If you can't compile successfully, try turning off your compiler's
optimizier.  Edit config.sh and change the line

	optimize='-O'

to something like

	optimize=' '

then propagate your changes with B<sh Configure -S> and rebuild
with B<make depend; make>.

=item *

If you still can't compile successfully, try adding a C<-DCRIPPLED_CC>
flag.  (Just because you get no errors doesn't mean it compiled right!)
This simplifies some complicated expressions for compilers that get
indigestion easily.

=item Missing functions

If you have missing routines, you probably need to add some library or
other, or you need to undefine some feature that Configure thought was
there but is defective or incomplete.  Look through config.h for
likely suspects.

=item *

Some compilers will not compile or optimize the larger files without
some extra switches to use larger jump offsets or allocate larger
internal tables.  You can customize the switches for each file in
F<cflags>.  It's okay to insert rules for specific files into
F<makefile> since a default rule only takes effect in the absence of a
specific rule.

=item Missing dbmclose

SCO prior to 3.2.4 may be missing dbmclose().  An upgrade to 3.2.4
that includes libdbm.nfs (which includes dbmclose()) may be available.

=item Warning (will try anyway): No library found for -lposix

If you see such a message during the building of an extension, but
the extension passes its tests anyway (see L<"make test"> below),
then don't worry about the warning message.  The extension
Makefile.PL goes looking for various libraries needed on various
systems; few systems will need all the possible libries listed.
For example, a system may have -lcposix or -lposix, but it's
unlikely to have both, so most users will see warnings for the one
they don't have.  The message 'will try anyway' is intended to
reassure you that the process is continuing.

On the other hand, if you are building GDBM_File and you get the
message

    Warning (will try anyway): No library found for -lgdbm

then it's likely you're going to run into trouble somewhere along
the line, since it's hard to see how you can use the GDBM_File
extension without the -lgdbm library.

It is true that, in principle, Configure could have figured all of
this out, but Configure and the extension building process are not
quite that tightly coordinated.

=item *

Some additional things that have been reported for either perl4 or perl5:

Genix may need to use libc rather than libc_s, or #undef VARARGS.

NCR Tower 32 (OS 2.01.01) may need -W2,-Sl,2000 and #undef MKDIR.

UTS may need one or more of B<-DCRIPPLED_CC>, B<-K> or B<-g>, and undef LSTAT.

If you get syntax errors on '(', try -DCRIPPLED_CC.

Machines with half-implemented dbm routines will need to #undef I_ODBM

db-recno failure on tests 51, 53 and 55:  Old versions of the DB library
(including the DB library which comes with FreeBSD 2.1) had broken
handling of recno databases with modified bval settings.  Upgrade your
DB library or OS.

=back

=head1 make test

This will run the regression tests on the perl you just made.  If it
doesn't say "All tests successful" then something went wrong.  See the
file F<t/README> in the F<t> subdirectory.  Note that you can't run it
in background if this disables opening of /dev/tty.

If B<make test> bombs out, just B<cd> to the F<t> directory and run
B<TEST> by hand to see if it makes any difference.  If individual tests
bomb, you can run them by hand, e.g.,

	./perl op/groups.t

You can also read the individual tests to see if there are any helpful
comments that apply to your system.

B<Note>: one possible reason for errors is that some external programs
may be broken due to the combination of your environment and the way
C<make test> exercises them.  For example, this may happen if you have
one or more of these environment variables set: C<LC_ALL LC_CTYPE
LC_COLLATE LANG>.  In some versions of UNIX, the non-English locales
are known to cause programs to exhibit mysterious errors.

If you have any of the above environment variables set, please try
C<setenv LC_ALL C> (for C shell) or <LC_ALL=C;export LC_ALL> (for
Bourne or Korn shell) from the command line and then retry C<make
test>.  If the tests then succeed, you may have a broken program that
is confusing the testing. Please run the troublesome test by hand as
shown above and see whether you can locate the program.  Look for
things like: C<exec, `backquoted command`, system, open("|...")> or
C<open("...|")>.  All these mean that Perl is trying to run some
external program.

=head1 INSTALLING PERL5

=head1 make install

This will put perl into the public directory you specified to
B<Configure>; by default this is F</usr/local/bin>.  It will also try
to put the man pages in a reasonable place.  It will not nroff the man
page, however.  You may need to be root to run B<make install>.  If you
are not root, you must own the directories in question and you should
ignore any messages about chown not working.

You may see some harmless error messages and warnings from pod2man.
You may safely ignore them.  (Yes, they should be fixed, but they
didn't seem important enough to warrant holding up the entire release.)

If you want to see exactly what will happen without installing
anything, you can run

	./perl installperl -n
	./perl installman -n

B<make install> will install the following:

	perl,
	    perl5.nnn	where nnn is the current release number.  This
			will be a link to perl.
	suidperl,
	    sperl5.nnn	If you requested setuid emulation.
	a2p          	awk-to-perl translator
	cppstdin	This is used by perl -P, if your cc -E can't
			read from stdin.
	c2ph, pstruct	Scripts for handling C structures in header files.
	s2p		sed-to-perl translator
	find2perl	find-to-perl translator
	h2xs		Converts C .h header files to Perl extensions.
	perlbug		Tool to report bugs in Perl.
	perldoc		Tool to read perl's pod documentation.
	pod2html,	Converters from perl's pod documentation format
	pod2latex, and 	to other useful formats.
	pod2man

	library files	in $privlib and $archlib specified to
			Configure, usually under /usr/local/lib/perl5/.
	man pages	in the location specified to Configure, usually
			something like /usr/local/man/man1.
	module		in the location specified to Configure, usually
	man pages	under /usr/local/lib/perl5/man/man3.
	pod/*.pod	in $privlib/pod/.

Installperl will also create the library directories $siteperl and
$sitearch listed in config.sh.  Usually, these are something like
	/usr/local/lib/perl5/site_perl/
	/usr/local/lib/perl5/site_perl/$archname
where $archname is something like sun4-sunos.  These directories
will be used for installing extensions.

Perl's *.h header files and the libperl.a library are also installed
under $archlib so that any user may later build new extensions, run the
optional Perl compiler, or embed the perl interpreter into another
program even if the Perl source is no longer available.

Most of the documentation in the pod/ directory is also available
in HTML and LaTeX format.  Type

	cd pod; make html; cd ..

to generate the html versions, and

	cd pod; make tex; cd ..

to generate the LaTeX versions.

=head1 cd /usr/include; h2ph *.h sys/*.h

Some of the perl library files need to be able to obtain information from
the system header files.  This command will convert the most commonly used
header files in F</usr/include> into files that can be easily interpreted
by perl.  These files will be placed in architectural library directory
you specified to B<Configure>; by default this is
F</usr/local/lib/perl5/ARCH/VERSION>, where B<ARCH> is your architecture
(such as C<sun4-solaris>) and B<VERSION> is the version of perl you are
building (for example, C<5.003>).

B<NOTE:> Due to differences in the C and perl languages, the conversion of
the header files in not perfect.  You may have to hand edit some of the
converted files to get them to parse correctly.  For example, it breaks
spectacularly on type casting and certain structures.

=head1 Coexistence with earlier versions of perl5.

You can safely install the current version of perl5 and still run scripts
under the old binaries for versions 5.003 and later ONLY.  Instead of
starting your script with #!/usr/local/bin/perl, just start it with
#!/usr/local/bin/perl5.003 (or whatever version you want to run.)
If you want to retain a version of perl5 prior to perl5.003, you'll
need to install the current version in a separate directory tree,
since some of the architecture-independent library files have changed
in incompatible ways.

The architecture-dependent files are stored in a version-specific
directory (such as F</usr/local/lib/perl5/sun4-sunos/5.002>) so that
they are still accessible.  I<Note:> perl5.000 and perl5.001 did not
put their architecture-dependent libraries in a version-specific
directory.  They are simply in F</usr/local/lib/perl5/$archname>.  If
you will not be using 5.000 or 5.001, you may safely remove those
files.

The standard library files in F</usr/local/lib/perl5>
should be usable by all versions of perl5.

Most extensions will probably not need to be recompiled to use with a newer
version of perl.  If you do run into problems, and you want to continue
to use the old version of perl along with your extension, simply move
those extension files to the appropriate version directory, such as
F</usr/local/lib/perl/archname/5.002>.  Then perl5.002 will find your
files in the 5.002 directory, and newer versions of perl will find your
newer extension in the site_perl directory.

Some users may prefer to keep all versions of perl in completely
separate directories.  One convenient way to do this is by
using a separate prefix for each version, such as

	sh Configure -Dprefix=/opt/perl5.002

and adding /opt/perl5.002/bin to the shell PATH variable.  Such users
may also wish to add a symbolic link /usr/local/bin/perl so that
scripts can still start with #!/usr/local/bin/perl.

B<NOTE>: Starting with 5.002_01, all functions in the perl C source
code are protected by default by the prefix Perl_ (or perl_) so that
you may link with third-party libraries without fear of namespace
collisons.  This breaks compatability with
version 5.002, so once you install 5.002_01 (or higher) you will
need to re-build and install all of your dynamically loadable
extensions.  (The standard extensions supplied with Perl are handled
automatically).  You can turn off this namespace protection by adding
-DNO_EMBED to your ccflags variable in config.sh.

In the future, we certainly hope that most extensions won't need to be
recompiled for use with a newer version of perl.

=head1 Coexistence with perl4

You can safely install perl5 even if you want to keep perl4 around.

By default, the perl5 libraries go into F</usr/local/lib/perl5/>, so
they don't override the perl4 libraries in F</usr/local/lib/perl/>.

In your /usr/local/bin directory, you should have a binary named
F<perl4.036>.  That will not be touched by the perl5 installation
process.  Most perl4 scripts should run just fine under perl5.
However, if you have any scripts that require perl4, you can replace
the C<#!> line at the top of them by C<#!/usr/local/bin/perl4.036>
(or whatever the appropriate pathname is).  See pod/perltrap.pod
for possible problems running perl4 scripts under perl5.

=head1 DOCUMENTATION

Read the manual entries before running perl.  The main documentation is
in the pod/ subdirectory and should have been installed during the
build process.  Type B<man perl> to get started.  Alternatively, you
can type B<perldoc perl> to use the supplied B<perldoc> script.  This
is sometimes useful for finding things in the library modules.

=head1 AUTHOR

Andy Dougherty <doughera@lafcol.lafayette.edu>, borrowing I<very> heavily
from the original README by Larry Wall.

=head1 LAST MODIFIED

24 December 1996