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    1 If you read this file _as_is_, just ignore the funny characters you see.
    2 It is written in the POD format (see F<pod/perlpod.pod>) which is specially
    3 designed to be readable as is.
    5 =head1 NAME
    7 INSTALL - Build and Installation guide for perl 5.
    9 =head1 SYNOPSIS
   11 First, make sure you have an up-to-date version of Perl.  If you
   12 didn't get your Perl source from CPAN, check the latest version at
   13 L<https://www.cpan.org/src/>.  Perl uses a version scheme where even-numbered
   14 subreleases (like 5.8.x and 5.10.x) are stable maintenance releases and
   15 odd-numbered subreleases (like 5.7.x and 5.9.x) are unstable
   16 development releases.  Development releases should not be used in
   17 production environments.  Fixes and new features are first carefully
   18 tested in development releases and only if they prove themselves to be
   19 worthy will they be migrated to the maintenance releases.
   21 The basic steps to build and install perl 5 on a Unix system with all
   22 the defaults are to run, from a freshly unpacked source tree:
   24 	sh Configure -de
   25 	make
   26 	make test
   27 	make install
   29 Each of these is explained in further detail below.
   31 The above commands will install Perl to F</usr/local> (or some other
   32 platform-specific directory -- see the appropriate file in F<hints/>.)
   33 If that's not okay with you, you can run Configure interactively, by
   34 just typing "sh Configure" (without the -de args). You can also specify
   35 any prefix location by adding C<"-Dprefix='/some/dir'"> to Configure's args.
   36 To explicitly name the perl binary, use the command
   37 "make install PERLNAME=myperl".
   39 Building perl from source requires an ANSI compliant C compiler.
   40 A minimum of C89 is required. Some features available in C99 will
   41 be probed for and used when found. The perl build process does not
   42 rely on anything more than C89.
   44 These options, and many more, are explained in further detail below.
   46 If you're building perl from a git repository, you should also consult
   47 the documentation in F<pod/perlgit.pod> for information on that special
   48 circumstance.
   50 If you have problems, corrections, or questions, please see
   51 L<"Reporting Problems"> below.
   53 For information on what's new in this release, see the
   54 F<pod/perldelta.pod> file.  For more information about how to find more
   55 specific detail about changes, see the Changes file.
   57 =head1 DESCRIPTION
   59 This document is written in pod format as an easy way to indicate its
   60 structure.  The pod format is described in F<pod/perlpod.pod>, but you can
   61 read it as is with any pager or editor.  Headings and items are marked
   62 by lines beginning with '='.  The other mark-up used is
   64     B<text>     embolden text, used for switches, programs or commands
   65     C<code>	literal code
   66     L<name>     A link (cross reference) to name
   67     F<file>     A filename
   69 Although most of the defaults are probably fine for most users,
   70 you should probably at least skim through this document before
   71 proceeding.
   73 In addition to this file, check if there is a README file specific to
   74 your operating system, since it may provide additional or different
   75 instructions for building Perl.  If there is a hint file for your
   76 system (in the F<hints/> directory) you might also want to read it
   77 for even more information.
   79 For additional information about porting Perl, see the section on
   80 L<"Porting information"> below, and look at the files in the F<Porting/>
   81 directory.
   83 =head1 PRELIMINARIES
   85 =head2 Changes and Incompatibilities
   87 Please see F<pod/perldelta.pod> for a description of the changes and
   88 potential incompatibilities introduced with this release.  A few of
   89 the most important issues are listed below, but you should refer
   90 to F<pod/perldelta.pod> for more detailed information.
   92 B<WARNING:> This version is not binary compatible with versions of Perl
   93 earlier than 5.32.0.  If you have built extensions (i.e. modules that
   94 include C code) using an earlier version of Perl, you will need to
   95 rebuild and reinstall those extensions.
   97 Pure perl modules without XS or C code should continue to work fine
   98 without reinstallation.  See the discussion below on
   99 L<"Coexistence with earlier versions of perl 5"> for more details.
  101 The standard extensions supplied with Perl will be handled automatically.
  103 On a related issue, old modules may possibly be affected by the changes
  104 in the Perl language in the current release.  Please see
  105 F<pod/perldelta.pod> for a description of what's changed.  See your
  106 installed copy of the perllocal.pod file for a (possibly incomplete)
  107 list of locally installed modules.  Also see the L<CPAN> module's
  108 C<autobundle> function for one way to make a "bundle" of your currently
  109 installed modules.
  111 =head1 Run Configure
  113 Configure will figure out various things about your system.  Some
  114 things Configure will figure out for itself, other things it will ask
  115 you about.  To accept the default, just press RETURN.   The default is
  116 almost always okay.  It is normal for some things to be "NOT found",
  117 since Configure often searches for many different ways of performing
  118 the same function.
  120 At any Configure prompt, you can type  &-d  and Configure will use the
  121 defaults from then on.
  123 After it runs, Configure will perform variable substitution on all the
  124 *.SH files and offer to run make depend.
  126 The results of a Configure run are stored in the config.sh and Policy.sh
  127 files.
  129 =head2 Common Configure options
  131 Configure supports a number of useful options.  Run
  133 	Configure -h
  135 to get a listing.  See the F<Porting/Glossary> file for a complete list of
  136 Configure variables you can set and their definitions.
  138 =over 4
  140 =item C compiler
  142 To compile with gcc, if it's not the default compiler on your
  143 system, you should run
  145 	sh Configure -Dcc=gcc
  147 This is the preferred way to specify gcc (or any another alternative
  148 compiler) so that the hints files can set appropriate defaults.
  150 =item Installation prefix
  152 By default, for most systems, perl will be installed in
  153 F</usr/local/>{F<bin>, F<lib>, F<man>}.  (See L<"Installation Directories">
  154 and L<"Coexistence with earlier versions of perl 5"> below for
  155 further details.)
  157 You can specify a different 'prefix' for the default installation
  158 directory when Configure prompts you, or by using the Configure command
  159 line option C<-Dprefix='/some/directory'>, e.g.
  161 	sh Configure -Dprefix=/opt/perl
  163 If your prefix contains the string "perl", then the suggested
  164 directory structure is simplified.  For example, if you use
  165 C<prefix=/opt/perl>, then Configure will suggest F</opt/perl/lib> instead of
  166 F</opt/perl/lib/perl5/>.  Again, see L<"Installation Directories"> below
  167 for more details.  Do not include a trailing slash, (i.e. F</opt/perl/>)
  168 or you may experience odd test failures.
  170 NOTE:  You must not specify an installation directory that is the same
  171 as or below your perl source directory.  If you do, installperl will
  172 attempt infinite recursion.
  174 =item F</usr/bin/perl>
  176 It may seem obvious, but Perl is useful only when users can easily
  177 find it.  It's often a good idea to have both F</usr/bin/perl> and
  178 F</usr/local/bin/perl> be symlinks to the actual binary.  Be especially
  179 careful, however, not to overwrite a version of perl supplied by your
  180 vendor unless you are sure you know what you are doing.  If you insist
  181 on replacing your vendor's perl, useful information on how it was
  182 configured may be found with
  184 	perl -V:config_args
  186 (Check the output carefully, however, since this doesn't preserve
  187 spaces in arguments to Configure.  For that, you have to look carefully
  188 at config_arg1, config_arg2, etc.)
  190 By default, Configure will not try to link F</usr/bin/perl> to the current
  191 version of perl.  You can turn on that behavior by running
  193 	Configure -Dinstallusrbinperl
  195 or by answering 'yes' to the appropriate Configure prompt.
  197 In any case, system administrators are strongly encouraged to put
  198 (symlinks to) perl and its accompanying utilities, such as perldoc,
  199 into a directory typically found along a user's PATH, or in another
  200 obvious and convenient place.
  202 =item Building a development release
  204 For development releases (odd subreleases, like 5.9.x) if you want to
  205 use Configure -d, you will also need to supply -Dusedevel to Configure,
  206 because the default answer to the question "do you really want to
  207 Configure a development version?" is "no".  The -Dusedevel skips that
  208 sanity check.
  210 =back
  212 If you are willing to accept all the defaults, and you want terse
  213 output, you can run
  215 	sh Configure -des
  217 =head2 Altering Configure variables for C compiler switches etc.
  219 For most users, most of the Configure defaults are fine, or can easily
  220 be set on the Configure command line.  However, if Configure doesn't
  221 have an option to do what you want, you can change Configure variables
  222 after the platform hints have been run by using Configure's -A switch.
  223 For example, here's how to add a couple of extra flags to C compiler
  224 invocations:
  226 	sh Configure -Accflags="-DPERL_EXTERNAL_GLOB -DNO_HASH_SEED"
  228 To clarify, those ccflags values are not Configure options; if passed to
  229 Configure directly, they won't do anything useful (they will define a
  230 variable in config.sh, but without taking any action based upon it).
  231 But when passed to the compiler, those flags will activate #ifdefd code.
  233 For more help on Configure switches, run
  235 	sh Configure -h
  237 =head2 Major Configure-time Build Options
  239 There are several different ways to Configure and build perl for your
  240 system.  For most users, the defaults are sensible and will work.
  241 Some users, however, may wish to further customize perl.  Here are
  242 some of the main things you can change.
  244 =head3 Threads
  246 On some platforms, perl can be compiled with support for threads.  To
  247 enable this, run
  249 	sh Configure -Dusethreads
  251 The default is to compile without thread support.
  253 Perl used to have two different internal threads implementations.  The
  254 current model (available internally since 5.6, and as a user-level module
  255 since 5.8) is called interpreter-based implementation (ithreads), with
  256 one interpreter per thread, and explicit sharing of data. The (deprecated)
  257 5.005 version (5005threads) was removed for release 5.10.
  259 The 'threads' module is for use with the ithreads implementation.  The
  260 'Thread' module emulates the old 5005threads interface on top of the
  261 current ithreads model.
  263 When using threads, perl uses a dynamically-sized buffer for some of
  264 the thread-safe library calls, such as those in the getpw*() family.
  265 This buffer starts small, but it will keep growing until the result
  266 fits.  To get a fixed upper limit, you should compile Perl with
  267 PERL_REENTRANT_MAXSIZE defined to be the number of bytes you want.  One
  268 way to do this is to run Configure with
  269 C<-Accflags=-DPERL_REENTRANT_MAXSIZE=65536>.
  271 =head3 Large file support
  273 Since Perl 5.6.0, Perl has supported large files (files larger than
  274 2 gigabytes), and in many common platforms like Linux or Solaris this
  275 support is on by default.
  277 This is both good and bad. It is good in that you can use large files,
  278 seek(), stat(), and -s them.  It is bad in that if you are interfacing
  279 Perl using some extension, the components you are connecting to must also
  280 be large file aware: if Perl thinks files can be large but the other
  281 parts of the software puzzle do not understand the concept, bad things
  282 will happen.
  284 There's also one known limitation with the current large files
  285 implementation: unless you also have 64-bit integers (see the next
  286 section), you cannot use the printf/sprintf non-decimal integer formats
  287 like C<%x> to print filesizes.  You can use C<%d>, though.
  289 If you want to compile perl without large file support, use
  291     sh Configure -Uuselargefiles
  293 =head3 64 bit support
  295 If your platform does not run natively at 64 bits, but can simulate
  296 them with compiler flags and/or C<long long> or C<int64_t>,
  297 you can build a perl that uses 64 bits.
  299 There are actually two modes of 64-bitness: the first one is achieved
  300 using Configure -Duse64bitint and the second one using Configure
  301 -Duse64bitall.  The difference is that the first one is minimal and
  302 the second one maximal.  The first works in more places than the second.
  304 The C<use64bitint> option does only as much as is required to get
  305 64-bit integers into Perl (this may mean, for example, using "long
  306 longs") while your memory may still be limited to 2 gigabytes (because
  307 your pointers could still be 32-bit).  Note that the name C<64bitint>
  308 does not imply that your C compiler will be using 64-bit C<int>s (it
  309 might, but it doesn't have to).  The C<use64bitint> simply means that
  310 you will be able to have 64 bit-wide scalar values.
  312 The C<use64bitall> option goes all the way by attempting to switch
  313 integers (if it can), longs (and pointers) to being 64-bit.  This may
  314 create an even more binary incompatible Perl than -Duse64bitint: the
  315 resulting executable may not run at all in a 32-bit box, or you may
  316 have to reboot/reconfigure/rebuild your operating system to be 64-bit
  317 aware.
  319 Natively 64-bit systems need neither -Duse64bitint nor -Duse64bitall.
  320 On these systems, it might be the default compilation mode, and there
  321 is currently no guarantee that passing no use64bitall option to the
  322 Configure process will build a 32bit perl. Implementing -Duse32bit*
  323 options is planned for a future release of perl.
  325 =head3 Long doubles
  327 In some systems you may be able to use long doubles to enhance the
  328 range and precision of your double precision floating point numbers
  329 (that is, Perl's numbers).  Use Configure -Duselongdouble to enable
  330 this support (if it is available).
  332 Note that the exact format and range of long doubles varies:
  333 the most common is the x86 80-bit (64 bits of mantissa) format,
  334 but there are others, with different mantissa and exponent ranges.
  336 =head3 "more bits"
  338 You can "Configure -Dusemorebits" to turn on both the 64-bit support
  339 and the long double support.
  341 =head3 quadmath
  343 One option for more precision is that gcc 4.6 and later have a library
  344 called quadmath, which implements the IEEE 754 quadruple precision
  345 (128-bit, 113 bits of mantissa) floating point numbers.  The library
  346 works at least on x86 and ia64 platforms.  It may be part of your gcc
  347 installation, or you may need to install it separately.
  349 With "Configure -Dusequadmath" you can try enabling its use, but note
  350 the compiler dependency, you may need to also add "-Dcc=...".
  351 At C level the type is called C<__float128> (note, not "long double"),
  352 but Perl source knows it as NV.  (This is not "long doubles".)
  354 =head3 Algorithmic Complexity Attacks on Hashes
  356 Perl 5.18 reworked the measures used to secure its hash function
  357 from algorithmic complexity attacks.  By default it will build with
  358 all of these measures enabled along with support for controlling and
  359 disabling them via environment variables.
  361 You can override various aspects of this feature by defining various
  362 symbols during configure. An example might be:
  364     sh Configure -Accflags=-DPERL_HASH_FUNC_SIPHASH
  366 B<Unless stated otherwise these options are considered experimental or
  367 insecure and are not recommended for production use.>
  369 Since Perl 5.18 we have included support for multiple hash functions,
  370 although from time to time we change which functions we support,
  371 and which function is default (currently SBOX+STADTX on 64 bit builds
  372 and SBOX+ZAPHOD32 for 32 bit builds). You can choose a different
  373 algorithm by defining one of the following symbols during configure.
  374 Note that there security implications of which hash function you choose
  375 to use. The functions are listed roughly by how secure they are believed
  376 to be, with the one believed to be most secure at release time being PERL_HASH_FUNC_SIPHASH.
  383 In addition, these, (or custom hash functions), may be "fronted" by the
  384 SBOX32 hash function for keys under a chosen size. This hash function is
  385 special in that it has proven theoretical security properties, and is very
  386 fast to hash, but which by nature is restricted to a maximum key length,
  387 and which has rather expensive setup costs (relatively speaking), both in
  388 terms of performance and more importantly in terms of memory. SBOX32
  389 requires 1k of storage per character it can hash, and it must populate that
  390 storage with 256 32-bit random values as well. In practice the RNG we use
  391 for seeding the SBOX32 storage is very efficient and populating the table
  392 required for hashing even fairly long keys is negligible as we only do it
  393 during startup. By default we build with SBOX32 enabled, but you change that
  394 by setting
  398 to zero in configure. By default Perl will use SBOX32 to hash strings 24 bytes
  399 or shorter, you can change this length by setting
  401     SBOX32_MAX_LEN
  403 to the desired length, with the maximum length being 256.
  405 As of Perl 5.18 the order returned by keys(), values(), and each() is
  406 non-deterministic and distinct per hash, and the insert order for
  407 colliding keys is randomized as well, and perl allows for controlling this
  408 by the PERL_PERTURB_KEYS environment setting. You can disable this behavior
  409 entirely with the define
  413 You can disable the environment variable checks and compile time specify
  414 the type of key traversal randomization to be used by defining one of these:
  419 Since Perl 5.18 the seed used for the hash function is randomly selected
  420 at process start, which can be overridden by specifying a seed by setting
  421 the PERL_HASH_SEED environment variable.
  423 You can change this behavior so that your perl is built with a hard coded
  424 seed with the define
  426     NO_HASH_SEED
  428 Note that if you do this you should modify the code in hv_func.h to specify
  429 your own key. In the future this define may be renamed and replaced with one
  430 that requires you to specify the key to use.
  432 B<NOTE WELL: Perl has never guaranteed any ordering of the hash keys>, and the
  433 ordering has already changed several times during the lifetime of Perl
  434 5.  Also, the ordering of hash keys has always been, and continues to
  435 be, affected by the insertion order regardless of whether you build with
  436 or without the randomization features.  Note that because of this
  437 and especially with randomization that the key order of a hash is *undefined*
  438 and that things like Data::Dumper, for example, may produce different output
  439 between different runs of Perl, since Data::Dumper serializes the key in the
  440 native order for the hash.  The use of the Data::Dumper C<Sortkeys> option is
  441 recommended if you are comparing dumps between different invocations of perl.
  443 See L<perlrun/PERL_HASH_SEED> and L<perlrun/PERL_PERTURB_KEYS> for
  444 details on the environment variables, and L<perlsec/Algorithmic
  445 Complexity Attacks> for further security details.
  447 The C<PERL_HASH_SEED> and PERL_PERTURB_KEYS> environment variables can
  448 be disabled by building configuring perl with
  449 C<-Accflags=-DNO_PERL_HASH_ENV>.
  451 The C<PERL_HASH_SEED_DEBUG> environment variable can be disabled by
  452 configuring perl with C<-Accflags=-DNO_PERL_HASH_SEED_DEBUG>.
  454 =head3 SOCKS
  456 Perl can be configured to be 'socksified', that is, to use the SOCKS
  457 TCP/IP proxy protocol library.  SOCKS is used to give applications
  458 access to transport layer network proxies.  Perl supports only SOCKS
  459 Version 5.  The corresponding Configure option is -Dusesocks.
  460 You can find more about SOCKS from wikipedia at
  461 L<https://en.wikipedia.org/wiki/SOCKS>.
  463 =head3 Dynamic Loading
  465 By default, Configure will compile perl to use dynamic loading.
  466 If you want to force perl to be compiled completely
  467 statically, you can either choose this when Configure prompts you or
  468 you can use the Configure command line option -Uusedl.
  469 With this option, you won't be able to use any new extension
  470 (XS) module without recompiling perl itself.
  472 =head3 Building a shared Perl library
  474 Currently, for most systems, the main perl executable is built by
  475 linking the "perl library" libperl.a with perlmain.o, your static
  476 extensions, and various extra libraries, such as -lm.
  478 On systems that support dynamic loading, it may be possible to
  479 replace libperl.a with a shared libperl.so.  If you anticipate building
  480 several different perl binaries (e.g. by embedding libperl into
  481 different programs, or by using the optional compiler extension), then
  482 you might wish to build a shared libperl.so so that all your binaries
  483 can share the same library.
  485 The disadvantages are that there may be a significant performance
  486 penalty associated with the shared libperl.so, and that the overall
  487 mechanism is still rather fragile with respect to different versions
  488 and upgrades.
  490 In terms of performance, on my test system (Solaris 2.5_x86) the perl
  491 test suite took roughly 15% longer to run with the shared libperl.so.
  492 Your system and typical applications may well give quite different
  493 results.
  495 The default name for the shared library is typically something like
  496 libperl.so.5.8.8 (for Perl 5.8.8), or libperl.so.588, or simply
  497 libperl.so.  Configure tries to guess a sensible naming convention
  498 based on your C library name.  Since the library gets installed in a
  499 version-specific architecture-dependent directory, the exact name
  500 isn't very important anyway, as long as your linker is happy.
  502 You can elect to build a shared libperl by
  504 	sh Configure -Duseshrplib
  506 To build a shared libperl, the environment variable controlling shared
  507 library search (LD_LIBRARY_PATH in most systems, DYLD_LIBRARY_PATH for
  509 for HP-UX, LIBPATH for AIX, PATH for Cygwin) must be set up to include
  510 the Perl build directory because that's where the shared libperl will
  511 be created.  Configure arranges makefile to have the correct shared
  512 library search settings.  You can find the name of the environment
  513 variable Perl thinks works in your your system by
  515 	grep ldlibpthname config.sh
  517 However, there are some special cases where manually setting the
  518 shared library path might be required.  For example, if you want to run
  519 something like the following with the newly-built but not-yet-installed
  520 ./perl:
  522         ./perl -I. -MTestInit t/misc/failing_test.t
  524 or
  526         ./perl -Ilib ~/my_mission_critical_test
  528 then you need to set up the shared library path explicitly.
  529 You can do this with
  533 for Bourne-style shells, or
  535    setenv LD_LIBRARY_PATH `pwd`
  537 for Csh-style shells.  (This procedure may also be needed if for some
  538 unexpected reason Configure fails to set up makefile correctly.) (And
  539 again, it may be something other than LD_LIBRARY_PATH for you, see above.)
  541 You can often recognize failures to build/use a shared libperl from error
  542 messages complaining about a missing libperl.so (or libperl.sl in HP-UX),
  543 for example:
  545     18126:./miniperl: /sbin/loader: Fatal Error: cannot map libperl.so
  547 There is also an potential problem with the shared perl library if you
  548 want to have more than one "flavor" of the same version of perl (e.g.
  549 with and without -DDEBUGGING).  For example, suppose you build and
  550 install a standard Perl 5.10.0 with a shared library.  Then, suppose you
  551 try to build Perl 5.10.0 with -DDEBUGGING enabled, but everything else
  552 the same, including all the installation directories.  How can you
  553 ensure that your newly built perl will link with your newly built
  554 libperl.so.8 rather with the installed libperl.so.8?  The answer is
  555 that you might not be able to.  The installation directory is encoded
  556 in the perl binary with the LD_RUN_PATH environment variable (or
  557 equivalent ld command-line option).  On Solaris, you can override that
  558 with LD_LIBRARY_PATH; on Linux, you can only override at runtime via
  559 LD_PRELOAD, specifying the exact filename you wish to be used; and on
  560 Digital Unix, you can override LD_LIBRARY_PATH by setting the
  561 _RLD_ROOT environment variable to point to the perl build directory.
  563 In other words, it is generally not a good idea to try to build a perl
  564 with a shared library if $archlib/CORE/$libperl already exists from a
  565 previous build.
  567 A good workaround is to specify a different directory for the
  568 architecture-dependent library for your -DDEBUGGING version of perl.
  569 You can do this by changing all the *archlib* variables in config.sh to
  570 point to your new architecture-dependent library.
  572 =head3 Environment access
  574 Perl often needs to write to the program's environment, such as when
  575 C<%ENV> is assigned to. Many implementations of the C library function
  576 C<putenv()> leak memory, so where possible perl will manipulate the
  577 environment directly to avoid these leaks. The default is now to perform
  578 direct manipulation whenever perl is running as a stand alone interpreter,
  579 and to call the safe but potentially leaky C<putenv()> function when the
  580 perl interpreter is embedded in another application. You can force perl
  581 to always use C<putenv()> by compiling with
  582 C<-Accflags="-DPERL_USE_SAFE_PUTENV">, see section L</"Altering Configure
  583 variables for C compiler switches etc.">.  You can force an embedded perl
  584 to use direct manipulation by setting C<PL_use_safe_putenv = 0;> after
  585 the C<perl_construct()> call.
  587 =head3 External glob
  589 Before File::Glob entered core in 5.6.0 globbing was implemented by shelling
  590 out. If the environmental variable PERL_EXTERNAL_GLOB is defined and if the
  591 F<csh> shell is available, perl will still do this the old way.
  593 =head2 Installation Directories
  595 The installation directories can all be changed by answering the
  596 appropriate questions in Configure.  For convenience, all the installation
  597 questions are near the beginning of Configure.  Do not include trailing
  598 slashes on directory names.  At any point during the Configure process,
  599 you can answer a question with  &-d  and Configure will use the defaults
  600 from then on.  Alternatively, you can
  602 	grep '^install' config.sh
  604 after Configure has run to verify the installation paths.
  606 The defaults are intended to be reasonable and sensible for most
  607 people building from sources.  Those who build and distribute binary
  608 distributions or who export perl to a range of systems will probably
  609 need to alter them.  If you are content to just accept the defaults,
  610 you can safely skip the next section.
  612 The directories set up by Configure fall into three broad categories.
  614 =over 4
  616 =item Directories for the perl distribution
  618 By default, Configure will use the following directories for 5.32.1.
  619 $version is the full perl version number, including subversion, e.g.
  620 5.12.3, and $archname is a string like sun4-sunos,
  621 determined by Configure.  The full definitions of all Configure
  622 variables are in the file Porting/Glossary.
  624     Configure variable	Default value
  625     $prefixexp		/usr/local
  626     $binexp		$prefixexp/bin
  627     $scriptdirexp	$prefixexp/bin
  628     $privlibexp		$prefixexp/lib/perl5/$version
  629     $archlibexp		$prefixexp/lib/perl5/$version/$archname
  630     $man1direxp		$prefixexp/man/man1
  631     $man3direxp		$prefixexp/man/man3
  632     $html1direxp	(none)
  633     $html3direxp	(none)
  635 $prefixexp is generated from $prefix, with ~ expansion done to convert
  636 home directories into absolute paths. Similarly for the other variables
  637 listed. As file system calls do not do this, you should always reference
  638 the ...exp variables, to support users who build perl in their home
  639 directory.
  641 Actually, Configure recognizes the SVR3-style
  642 /usr/local/man/l_man/man1 directories, if present, and uses those
  643 instead.  Also, if $prefix contains the string "perl", the library
  644 directories are simplified as described below.  For simplicity, only
  645 the common style is shown here.
  647 =item Directories for site-specific add-on files
  649 After perl is installed, you may later wish to add modules (e.g. from
  650 CPAN) or scripts.  Configure will set up the following directories to
  651 be used for installing those add-on modules and scripts.
  653    Configure        Default
  654    variable          value
  655  $siteprefixexp    $prefixexp
  656  $sitebinexp       $siteprefixexp/bin
  657  $sitescriptexp    $siteprefixexp/bin
  658  $sitelibexp       $siteprefixexp/lib/perl5/site_perl/$version
  659  $sitearchexp
  660                $siteprefixexp/lib/perl5/site_perl/$version/$archname
  661  $siteman1direxp   $siteprefixexp/man/man1
  662  $siteman3direxp   $siteprefixexp/man/man3
  663  $sitehtml1direxp  (none)
  664  $sitehtml3direxp  (none)
  666 By default, ExtUtils::MakeMaker will install architecture-independent
  667 modules into $sitelib and architecture-dependent modules into $sitearch.
  669 =item Directories for vendor-supplied add-on files
  671 Lastly, if you are building a binary distribution of perl for
  672 distribution, Configure can optionally set up the following directories
  673 for you to use to distribute add-on modules.
  675    Configure          Default
  676    variable            value
  677  $vendorprefixexp    (none)
  679  (The next ones are set only if vendorprefix is set.)
  681  $vendorbinexp       $vendorprefixexp/bin
  682  $vendorscriptexp    $vendorprefixexp/bin
  683  $vendorlibexp       $vendorprefixexp/lib/perl5/vendor_perl/$version
  684  $vendorarchexp
  685            $vendorprefixexp/lib/perl5/vendor_perl/$version/$archname
  686  $vendorman1direxp   $vendorprefixexp/man/man1
  687  $vendorman3direxp   $vendorprefixexp/man/man3
  688  $vendorhtml1direxp  (none)
  689  $vendorhtml3direxp  (none)
  691 These are normally empty, but may be set as needed.  For example,
  692 a vendor might choose the following settings:
  694  $prefix           /usr
  695  $siteprefix       /usr/local
  696  $vendorprefix     /usr
  698 This would have the effect of setting the following:
  700  $binexp           /usr/bin
  701  $scriptdirexp     /usr/bin
  702  $privlibexp       /usr/lib/perl5/$version
  703  $archlibexp       /usr/lib/perl5/$version/$archname
  704  $man1direxp       /usr/man/man1
  705  $man3direxp       /usr/man/man3
  707  $sitebinexp       /usr/local/bin
  708  $sitescriptexp    /usr/local/bin
  709  $sitelibexp       /usr/local/lib/perl5/site_perl/$version
  710  $sitearchexp      /usr/local/lib/perl5/site_perl/$version/$archname
  711  $siteman1direxp   /usr/local/man/man1
  712  $siteman3direxp   /usr/local/man/man3
  714  $vendorbinexp     /usr/bin
  715  $vendorscriptexp  /usr/bin
  716  $vendorlibexp     /usr/lib/perl5/vendor_perl/$version
  717  $vendorarchexp    /usr/lib/perl5/vendor_perl/$version/$archname
  718  $vendorman1direxp /usr/man/man1
  719  $vendorman3direxp /usr/man/man3
  721 Note how in this example, the vendor-supplied directories are in the
  722 /usr hierarchy, while the directories reserved for the end user are in
  723 the /usr/local hierarchy.
  725 The entire installed library hierarchy is installed in locations with
  726 version numbers, keeping the installations of different versions distinct.
  727 However, later installations of Perl can still be configured to search
  728 the installed libraries corresponding to compatible earlier versions.
  729 See L<"Coexistence with earlier versions of perl 5"> below for more
  730 details on how Perl can be made to search older version directories.
  732 Of course you may use these directories however you see fit.  For
  733 example, you may wish to use $siteprefix for site-specific files that
  734 are stored locally on your own disk and use $vendorprefix for
  735 site-specific files that are stored elsewhere on your organization's
  736 network.  One way to do that would be something like
  738  sh Configure -Dsiteprefix=/usr/local -Dvendorprefix=/usr/share/perl
  740 =item otherlibdirs
  742 As a final catch-all, Configure also offers an $otherlibdirs
  743 variable.  This variable contains a colon-separated list of additional
  744 directories to add to @INC.  By default, it will be empty.
  745 Perl will search these directories (including architecture and
  746 version-specific subdirectories) for add-on modules and extensions.
  748 For example, if you have a bundle of perl libraries from a previous
  749 installation, perhaps in a strange place:
  751 	sh Configure -Dotherlibdirs=/usr/lib/perl5/site_perl/5.8.1
  753 =item APPLLIB_EXP
  755 There is one other way of adding paths to @INC at perl build time, and
  756 that is by setting the APPLLIB_EXP C pre-processor token to a colon-
  757 separated list of directories, like this
  759        sh Configure -Accflags='-DAPPLLIB_EXP=\"/usr/libperl\"'
  761 The directories defined by APPLLIB_EXP get added to @INC I<first>,
  762 ahead of any others, and so provide a way to override the standard perl
  763 modules should you, for example, want to distribute fixes without
  764 touching the perl distribution proper.  And, like otherlib dirs,
  765 version and architecture specific subdirectories are also searched, if
  766 present, at run time.  Of course, you can still search other @INC
  767 directories ahead of those in APPLLIB_EXP by using any of the standard
  768 run-time methods: $PERLLIB, $PERL5LIB, -I, use lib, etc.
  770 =item default_inc_excludes_dot
  772 Since version 5.26.0, default perl builds no longer includes C<'.'> as the
  773 last element of @INC. The old behaviour can restored using
  775 	sh Configure -Udefault_inc_excludes_dot
  777 Note that this is likely to make programs run under such a perl
  778 interpreter less secure.
  780 =item usesitecustomize
  782 Run-time customization of @INC can be enabled with:
  784 	sh Configure -Dusesitecustomize
  786 which will define USE_SITECUSTOMIZE and $Config{usesitecustomize}.
  787 When enabled, this makes perl run F<$sitelibexp/sitecustomize.pl> before
  788 anything else.  This script can then be set up to add additional
  789 entries to @INC.
  791 =item Man Pages
  793 By default, man pages will be installed in $man1dir and $man3dir, which
  794 are normally /usr/local/man/man1 and /usr/local/man/man3.  If you
  795 want to use a .3pm suffix for perl man pages, you can do that with
  797 	sh Configure -Dman3ext=3pm
  799 You can disable installation of man pages completely using
  801 	sh Configure -Dman1dir=none -Dman3dir=none
  803 =item HTML pages
  805 Currently, the standard perl installation does not do anything with
  806 HTML documentation, but that may change in the future.  Further, some
  807 add-on modules may wish to install HTML documents.  The html Configure
  808 variables listed above are provided if you wish to specify where such
  809 documents should be placed.  The default is "none", but will likely
  810 eventually change to something useful based on user feedback.
  812 =back
  814 Some users prefer to append a "/share" to $privlib and $sitelib
  815 to emphasize that those directories can be shared among different
  816 architectures.
  818 Note that these are just the defaults.  You can actually structure the
  819 directories any way you like.  They don't even have to be on the same
  820 filesystem.
  822 Further details about the installation directories, maintenance and
  823 development subversions, and about supporting multiple versions are
  824 discussed in L<"Coexistence with earlier versions of perl 5"> below.
  826 If you specify a prefix that contains the string "perl", then the
  827 library directory structure is slightly simplified.  Instead of
  828 suggesting $prefix/lib/perl5/, Configure will suggest $prefix/lib.
  830 Thus, for example, if you Configure with
  831 -Dprefix=/opt/perl, then the default library directories for 5.9.0 are
  833     Configure variable	Default value
  834 	$privlib	/opt/perl/lib/5.9.0
  835 	$archlib	/opt/perl/lib/5.9.0/$archname
  836 	$sitelib	/opt/perl/lib/site_perl/5.9.0
  837 	$sitearch	/opt/perl/lib/site_perl/5.9.0/$archname
  839 =head2 Changing the installation directory
  841 Configure distinguishes between the directory in which perl (and its
  842 associated files) should be installed, and the directory in which it
  843 will eventually reside.  For most sites, these two are the same; for
  844 sites that use AFS, this distinction is handled automatically.
  845 However, sites that use package management software such as rpm or
  846 dpkg, or users building binary packages for distribution may also
  847 wish to install perl into a different directory before moving perl
  848 to its final destination.  There are two ways to do that:
  850 =over 4
  852 =item installprefix
  854 To install perl under the /tmp/perl5 directory, use the following
  855 command line:
  857     sh Configure -Dinstallprefix=/tmp/perl5
  859 (replace /tmp/perl5 by a directory of your choice).
  861 Beware, though, that if you go to try to install new add-on
  862 modules, they too will get installed in under '/tmp/perl5' if you
  863 follow this example.  That's why it's usually better to use DESTDIR,
  864 as shown in the next section.
  866 =item DESTDIR
  868 If you need to install perl on many identical systems, it is convenient
  869 to compile it once and create an archive that can be installed on
  870 multiple systems.  Suppose, for example, that you want to create an
  871 archive that can be installed in /opt/perl.  One way to do that is by
  872 using the DESTDIR variable during C<make install>.  The DESTDIR is
  873 automatically prepended to all the installation paths.  Thus you
  874 simply do:
  876     sh Configure -Dprefix=/opt/perl -des
  877     make
  878     make test
  879     make install DESTDIR=/tmp/perl5
  880     cd /tmp/perl5/opt/perl
  881     tar cvf /tmp/perl5-archive.tar .
  883 =back
  885 =head2 Relocatable @INC
  887 To create a relocatable perl tree, use the following command line:
  889     sh Configure -Duserelocatableinc
  891 Then the paths in @INC (and everything else in %Config) can be
  892 optionally located via the path of the perl executable.
  894 That means that, if the string ".../" is found at the start of any
  895 path, it's substituted with the directory of $^X. So, the relocation
  896 can be configured on a per-directory basis, although the default with
  897 "-Duserelocatableinc" is that everything is relocated. The initial
  898 install is done to the original configured prefix.
  900 This option is not compatible with the building of a shared libperl
  901 ("-Duseshrplib"), because in that case perl is linked with an hard-coded
  902 rpath that points at the libperl.so, that cannot be relocated.
  904 =head2 Site-wide Policy settings
  906 After Configure runs, it stores a number of common site-wide "policy"
  907 answers (such as installation directories) in the Policy.sh file.
  908 If you want to build perl on another system using the same policy
  909 defaults, simply copy the Policy.sh file to the new system's perl build
  910 directory, and Configure will use it. This will work even if Policy.sh was
  911 generated for another version of Perl, or on a system with a
  912 different architecture and/or operating system. However, in such cases,
  913 you should review the contents of the file before using it: for
  914 example, your new target may not keep its man pages in the same place
  915 as the system on which the file was generated.
  917 Alternatively, if you wish to change some or all of those policy
  918 answers, you should
  920 	rm -f Policy.sh
  922 to ensure that Configure doesn't re-use them.
  924 Further information is in the Policy_sh.SH file itself.
  926 If the generated Policy.sh file is unsuitable, you may freely edit it
  927 to contain any valid shell commands.  It will be run just after the
  928 platform-specific hints files.
  930 =head2 Disabling older versions of Perl
  932 Configure will search for binary compatible versions of previously
  933 installed perl binaries in the tree that is specified as target tree,
  934 and these will be used as locations to search for modules by the perl
  935 being built. The list of perl versions found will be put in the Configure
  936 variable inc_version_list.
  938 To disable this use of older perl modules, even completely valid pure
  939 perl modules, you can specify to not include the paths found:
  941        sh Configure -Dinc_version_list=none ...
  943 If you do want to use modules from some previous perl versions, the
  944 variable must contain a space separated list of directories under the
  945 site_perl directory, and has to include architecture-dependent
  946 directories separately, eg.
  948        sh Configure -Dinc_version_list="5.16.0/x86_64-linux 5.16.0" ...
  950 When using the newer perl, you can add these paths again in the
  951 PERL5LIB environment variable or with perl's -I runtime option.
  953 =head2 Building Perl outside of the source directory
  955 Sometimes it is desirable to build Perl in a directory different from
  956 where the sources are, for example if you want to keep your sources
  957 read-only, or if you want to share the sources between different binary
  958 architectures.  You can do this (if your file system supports symbolic
  959 links) by
  961 	mkdir /tmp/perl/build/directory
  962 	cd /tmp/perl/build/directory
  963 	sh /path/to/perl/source/Configure -Dmksymlinks ...
  965 This will create in /tmp/perl/build/directory a tree of symbolic links
  966 pointing to files in /path/to/perl/source.  The original files are left
  967 unaffected.  After Configure has finished you can just say
  969 	make
  970 	make test
  971 	make install
  973 as usual, and Perl will be built in /tmp/perl/build/directory.
  975 =head2 Building a debugging perl
  977 You can run perl scripts under the perl debugger at any time with
  978 B<perl -d your_script>.  If, however, you want to debug perl itself,
  979 you probably want to have support for perl internal debugging code
  980 (activated by adding -DDEBUGGING to ccflags), and/or support for the
  981 system debugger by adding -g to the optimisation flags.
  983 A perl compiled with the DEBUGGING C preprocessor macro will support the
  984 C<-D> perl command-line switch, have assertions enabled, and have many
  985 extra checks compiled into the code; but will execute much more slowly
  986 (typically 2-3x) and the binary will be much larger (typically 2-3x).
  988 As a convenience, debugging code (-DDEBUGGING) and debugging symbols (-g)
  989 can be enabled jointly or separately using a Configure switch, also
  990 (somewhat confusingly) named -DDEBUGGING.  For a more eye appealing call,
  991 -DEBUGGING is defined to be an alias for -DDEBUGGING. For both, the -U
  992 calls are also supported, in order to be able to overrule the hints or
  993 Policy.sh settings.
  995 Here are the DEBUGGING modes:
  997 =over 4
  999 =item Configure -DDEBUGGING
 1001 =item Configure -DEBUGGING
 1003 =item Configure -DEBUGGING=both
 1005 Sets both -DDEBUGGING in the ccflags, and adds -g to optimize.
 1007 You can actually specify -g and -DDEBUGGING independently (see below),
 1008 but usually it's convenient to have both.
 1010 =item Configure -DEBUGGING=-g
 1012 =item Configure -Doptimize=-g
 1014 Adds -g to optimize, but does not set -DDEBUGGING.
 1016 (Note:  Your system may actually require something like cc -g2.
 1017 Check your man pages for cc(1) and also any hint file for your system.)
 1019 =item Configure -DEBUGGING=none
 1021 =item Configure -UDEBUGGING
 1023 Removes -g from optimize, and -DDEBUGGING from ccflags.
 1025 =back
 1027 If you are using a shared libperl, see the warnings about multiple
 1028 versions of perl under L</Building a shared Perl library>.
 1030 Note that a perl built with -DDEBUGGING will be much bigger and will run
 1031 much, much more slowly than a standard perl.
 1033 =head2 DTrace support
 1035 On platforms where DTrace is available, it may be enabled by
 1036 using the -Dusedtrace option to Configure. DTrace probes are available
 1037 for subroutine entry (sub-entry) and subroutine exit (sub-exit). Here's a
 1038 simple D script that uses them:
 1040   perl$target:::sub-entry, perl$target:::sub-return {
 1041     printf("%s %s (%s:%d)\n", probename == "sub-entry" ? "->" : "<-",
 1042               copyinstr(arg0), copyinstr(arg1), arg2);
 1043   }
 1046 =head2 Extensions
 1048 Perl ships with a number of standard extensions.  These are contained
 1049 in the F<ext/> subdirectory.
 1051 By default, Configure will offer to build every extension which appears
 1052 to be supported.  For example, Configure will offer to build GDBM_File
 1053 only if it is able to find the gdbm library.
 1055 To disable certain extensions so that they are not built, use the
 1056 -Dnoextensions=... and -Donlyextensions=... options.  They both accept
 1057 a space-separated list of extensions, such as C<IPC/SysV>. The extensions
 1058 listed in
 1059 C<noextensions> are removed from the list of extensions to build, while
 1060 the C<onlyextensions> is rather more severe and builds only the listed
 1061 extensions.  The latter should be used with extreme caution since
 1062 certain extensions are used by many other extensions and modules:
 1063 examples of such modules include Fcntl and IO.  The order of processing
 1064 these options is first C<only> (if present), then C<no> (if present).
 1066 Of course, you may always run Configure interactively and select only
 1067 the extensions you want.
 1069 If you unpack any additional extensions in the ext/ directory before
 1070 running Configure, then Configure will offer to build those additional
 1071 extensions as well.  Most users probably shouldn't have to do this --
 1072 it is usually easier to build additional extensions later after perl
 1073 has been installed.  However, if you wish to have those additional
 1074 extensions statically linked into the perl binary, then this offers a
 1075 convenient way to do that in one step.  (It is not necessary, however;
 1076 you can build and install extensions just fine even if you don't have
 1077 dynamic loading.  See lib/ExtUtils/MakeMaker.pm for more details.)
 1078 Another way of specifying extra modules is described in
 1079 L<"Adding extra modules to the build"> below.
 1081 If you re-use an old config.sh but change your system (e.g. by
 1082 adding libgdbm) Configure will still offer your old choices of extensions
 1083 for the default answer, but it will also point out the discrepancy to
 1084 you.
 1086 =head2 Including locally-installed libraries
 1088 Perl comes with interfaces to number of libraries, including threads,
 1089 dbm, ndbm, gdbm, and Berkeley db.  For the *db* extension, if
 1090 Configure can find the appropriate header files and libraries, it will
 1091 automatically include that extension.  The threading extension needs
 1092 to be specified explicitly (see L</Threads>).
 1094 Those libraries are not distributed with perl. If your header (.h) files
 1095 for those libraries are not in a directory normally searched by your C
 1096 compiler, then you will need to include the appropriate -I/your/directory
 1097 option when prompted by Configure.  If your libraries are not in a
 1098 directory normally searched by your C compiler and linker, then you will
 1099 need to include the appropriate -L/your/directory option when prompted
 1100 by Configure. See the examples below.
 1102 =head3 Examples
 1104 =over 4
 1106 =item gdbm in /usr/local
 1108 Suppose you have gdbm and want Configure to find it and build the
 1109 GDBM_File extension.  This example assumes you have gdbm.h
 1110 installed in /usr/local/include/gdbm.h and libgdbm.a installed in
 1111 /usr/local/lib/libgdbm.a.  Configure should figure all the
 1112 necessary steps out automatically.
 1114 Specifically, when Configure prompts you for flags for
 1115 your C compiler, you should include -I/usr/local/include, if it's
 1116 not here yet. Similarly, when Configure prompts you for linker flags,
 1117 you should include -L/usr/local/lib.
 1119 If you are using dynamic loading, then when Configure prompts you for
 1120 linker flags for dynamic loading, you should again include
 1121 -L/usr/local/lib.
 1123 Again, this should all happen automatically.  This should also work if
 1124 you have gdbm installed in any of (/usr/local, /opt/local, /usr/gnu,
 1125 /opt/gnu, /usr/GNU, or /opt/GNU).
 1127 =item BerkeleyDB in /usr/local/BerkeleyDB
 1129 The version of BerkeleyDB distributed by Oracle installs in a
 1130 version-specific directory by default, typically something like
 1131 /usr/local/BerkeleyDB.4.7.  To have Configure find that, you need to add
 1132 -I/usr/local/BerkeleyDB.4.7/include to cc flags, as in the previous
 1133 example, and you will also have to take extra steps to help Configure
 1134 find -ldb.  Specifically, when Configure prompts you for library
 1135 directories, add /usr/local/BerkeleyDB.4.7/lib to the list.  Also, you
 1136 will need to add appropriate linker flags to tell the runtime linker
 1137 where to find the BerkeleyDB shared libraries.
 1139 It is possible to specify this from the command line (all on one
 1140 line):
 1142  sh Configure -de \
 1143     -Dlocincpth='/usr/local/BerkeleyDB.4.7/include             \
 1144                                            /usr/local/include' \
 1145     -Dloclibpth='/usr/local/BerkeleyDB.4.7/lib /usr/local/lib' \
 1146     -Aldflags='-R/usr/local/BerkeleyDB.4.7/lib'
 1148 locincpth is a space-separated list of include directories to search.
 1149 Configure will automatically add the appropriate -I directives.
 1151 loclibpth is a space-separated list of library directories to search.
 1152 Configure will automatically add the appropriate -L directives.
 1154 The addition to ldflags is so that the dynamic linker knows where to find
 1155 the BerkeleyDB libraries.  For Linux and Solaris, the -R option does that.
 1156 Other systems may use different flags.  Use the appropriate flag for your
 1157 system.
 1159 =back
 1161 =head2 Specifying a logical root directory
 1163 If you are cross-compiling, or are using a compiler which has it's own
 1164 headers and libraries in a nonstandard location, and your compiler
 1165 understands the C<--sysroot> option, you can use the C<-Dsysroot> option
 1166 to specify the logical root directory under which all libraries and
 1167 headers are searched for. This patch adjusts Configure to search under
 1168 $sysroot, instead of /.
 1170 --sysroot is added to ccflags and friends so that make in
 1171 ExtUtils::MakeMaker, and other extensions, will use it.
 1173 =head2 Overriding an old config.sh
 1175 If you want to use an old config.sh produced by a previous run of
 1176 Configure, but override some of the items with command line options, you
 1177 need to use B<Configure -O>.
 1179 =head2 GNU-style configure
 1181 If you prefer the GNU-style configure command line interface, you can
 1182 use the supplied configure.gnu command, e.g.
 1184 	CC=gcc ./configure.gnu
 1186 The configure.gnu script emulates a few of the more common configure
 1187 options.  Try
 1189 	./configure.gnu --help
 1191 for a listing.
 1193 (The file is called configure.gnu to avoid problems on systems
 1194 that would not distinguish the files "Configure" and "configure".)
 1196 =head2 Malloc Issues
 1198 Perl relies heavily on malloc(3) to grow data structures as needed,
 1199 so perl's performance can be noticeably affected by the performance of
 1200 the malloc function on your system.  The perl source is shipped with a
 1201 version of malloc that has been optimized for the typical requests from
 1202 perl, so there's a chance that it may be both faster and use less memory
 1203 than your system malloc.
 1205 However, if your system already has an excellent malloc, or if you are
 1206 experiencing difficulties with extensions that use third-party libraries
 1207 that call malloc, then you should probably use your system's malloc.
 1208 (Or, you might wish to explore the malloc flags discussed below.)
 1210 =over 4
 1212 =item Using the system malloc
 1214 To build without perl's malloc, you can use the Configure command
 1216 	sh Configure -Uusemymalloc
 1218 or you can answer 'n' at the appropriate interactive Configure prompt.
 1220 Note that Perl's malloc isn't always used by default; that actually
 1221 depends on your system. For example, on Linux and FreeBSD (and many more
 1222 systems), Configure chooses to use the system's malloc by default.
 1223 See the appropriate file in the F<hints/> directory to see how the
 1224 default is set.
 1228 NOTE: This flag is enabled automatically on some platforms if you just
 1229 run Configure to accept all the defaults.
 1231 Perl's malloc family of functions are normally called Perl_malloc(),
 1232 Perl_realloc(), Perl_calloc() and Perl_mfree().
 1233 These names do not clash with the system versions of these functions.
 1235 If this flag is enabled, however, Perl's malloc family of functions
 1236 will have the same names as the system versions.  This may be required
 1237 sometimes if you have libraries that like to free() data that may have
 1238 been allocated by Perl_malloc() and vice versa.
 1240 Note that enabling this option may sometimes lead to duplicate symbols
 1241 from the linker for malloc et al.  In such cases, the system probably
 1242 does not allow its malloc functions to be fully replaced with custom
 1243 versions.
 1247 This flag enables debugging mstats, which is required to use the
 1248 Devel::Peek::mstat() function. You cannot enable this unless you are
 1249 using Perl's malloc, so a typical Configure command would be
 1251        sh Configure -Accflags=-DPERL_DEBUGGING_MSTATS -Dusemymalloc
 1253 to enable this option.
 1255 =back
 1257 =head2 What if it doesn't work?
 1259 If you run into problems, try some of the following ideas.
 1260 If none of them help, then see L<"Reporting Problems"> below.
 1262 =over 4
 1264 =item Running Configure Interactively
 1266 If Configure runs into trouble, remember that you can always run
 1267 Configure interactively so that you can check (and correct) its
 1268 guesses.
 1270 All the installation questions have been moved to the top, so you don't
 1271 have to wait for them.  Once you've handled them (and your C compiler and
 1272 flags) you can type  &-d  at the next Configure prompt and Configure
 1273 will use the defaults from then on.
 1275 If you find yourself trying obscure command line incantations and
 1276 config.over tricks, I recommend you run Configure interactively
 1277 instead.  You'll probably save yourself time in the long run.
 1279 =item Hint files
 1281 Hint files tell Configure about a number of things:
 1283 =over 4
 1285 =item o
 1287 The peculiarities or conventions of particular platforms -- non-standard
 1288 library locations and names, default installation locations for binaries,
 1289 and so on.
 1291 =item o
 1293 The deficiencies of the platform -- for example, library functions that,
 1294 although present, are too badly broken to be usable; or limits on
 1295 resources that are generously available on most platforms.
 1297 =item o
 1299 How best to optimize for the platform, both in terms of binary size
 1300 and/or speed, and for Perl feature support. Because of wide variations in
 1301 the implementation of shared libraries and of threading, for example,
 1302 Configure often needs hints in order to be able to use these features.
 1304 =back
 1306 The perl distribution includes many system-specific hints files
 1307 in the hints/ directory. If one of them matches your system, Configure
 1308 will offer to use that hint file. Unless you have a very good reason
 1309 not to, you should accept its offer.
 1311 Several of the hint files contain additional important information.
 1312 If you have any problems, it is a good idea to read the relevant hint
 1313 file for further information.  See hints/solaris_2.sh for an extensive
 1314 example.  More information about writing good hints is in the
 1315 hints/README.hints file, which also explains hint files known as
 1316 callback-units.
 1318 Note that any hint file is read before any Policy file, meaning that
 1319 Policy overrides hints -- see L</Site-wide Policy settings>.
 1321 =item WHOA THERE!!!
 1323 If you are re-using an old config.sh, it's possible that Configure
 1324 detects different values from the ones specified in this file.  You will
 1325 almost always want to keep the previous value, unless you have changed
 1326 something on your system.
 1328 For example, suppose you have added libgdbm.a to your system
 1329 and you decide to reconfigure perl to use GDBM_File.  When you run
 1330 Configure again, you will need to add -lgdbm to the list of libraries.
 1331 Now, Configure will find your gdbm include file and library and will
 1332 issue a message:
 1334     *** WHOA THERE!!! ***
 1335 	The previous value for $i_gdbm on this machine was "undef"!
 1336 	Keep the previous value? [y]
 1338 In this case, you do not want to keep the previous value, so you
 1339 should answer 'n'.  (You'll also have to manually add GDBM_File to
 1340 the list of dynamic extensions to build.)
 1342 =item Changing Compilers
 1344 If you change compilers or make other significant changes, you should
 1345 probably not re-use your old config.sh.  Simply remove it or
 1346 rename it, then rerun Configure with the options you want to use.
 1348 =item Propagating your changes to config.sh
 1350 If you make any changes to config.sh, you should propagate
 1351 them to all the .SH files by running
 1353 	sh Configure -S
 1355 You will then have to rebuild by running
 1357 	make depend
 1358 	make
 1360 =item config.over and config.arch
 1362 You can also supply a shell script config.over to override
 1363 Configure's guesses.  It will get loaded up at the very end, just
 1364 before config.sh is created.  You have to be careful with this,
 1365 however, as Configure does no checking that your changes make sense.
 1366 This file is usually good for site-specific customizations.
 1368 There is also another file that, if it exists, is loaded before the
 1369 config.over, called config.arch.  This file is intended to be per
 1370 architecture, not per site, and usually it's the architecture-specific
 1371 hints file that creates the config.arch.
 1373 =item config.h
 1375 Many of the system dependencies are contained in config.h.
 1376 Configure builds config.h by running the config_h.SH script.
 1377 The values for the variables are taken from config.sh.
 1379 If there are any problems, you can edit config.h directly.  Beware,
 1380 though, that the next time you run Configure, your changes will be
 1381 lost.
 1383 =item cflags
 1385 If you have any additional changes to make to the C compiler command
 1386 line, they can be made in cflags.SH.  For instance, to turn off the
 1387 optimizer on toke.c, find the switch structure marked 'or customize here',
 1388 and add a line for toke.c ahead of the catch-all *) so that it now reads:
 1390     : or customize here
 1392     case "$file" in
 1393     toke) optimize='-g' ;;
 1394     *) ;;
 1396 You should not edit the generated file cflags directly, as your changes
 1397 will be lost the next time you run Configure, or if you edit config.sh.
 1399 To explore various ways of changing ccflags from within a hint file,
 1400 see the file hints/README.hints.
 1402 To change the C flags for all the files, edit config.sh and change either
 1403 $ccflags or $optimize, and then re-run
 1405 	sh Configure -S
 1406 	make depend
 1408 =item No sh
 1410 If you don't have sh, you'll have to copy the sample file
 1411 Porting/config.sh to config.sh and edit your config.sh to reflect your
 1412 system's peculiarities.  See Porting/pumpkin.pod for more information.
 1413 You'll probably also have to extensively modify the extension building
 1414 mechanism.
 1416 =item Porting information
 1418 Specific information for the OS/2, Plan 9, VMS and Win32 ports is in the
 1419 corresponding README files and subdirectories.  Additional information,
 1420 including a glossary of all those config.sh variables, is in the Porting
 1421 subdirectory.  Porting/Glossary should especially come in handy.
 1423 Ports for other systems may also be available.  You should check out
 1424 L<https://www.cpan.org/ports> for current information on ports to
 1425 various other operating systems.
 1427 If you plan to port Perl to a new architecture, study carefully the
 1428 section titled "Philosophical Issues in Patching and Porting Perl"
 1429 in the file Porting/pumpkin.pod and the file pod/perlgit.pod.
 1430 Study also how other non-UNIX ports have solved problems.
 1432 =back
 1434 =head2 Adding extra modules to the build
 1436 You can specify extra modules or module bundles to be fetched from the
 1437 CPAN and installed as part of the Perl build.  Either use the -Dextras=...
 1438 command line parameter to Configure, for example like this:
 1440 	Configure -Dextras="Bundle::LWP DBI"
 1442 or answer first 'y' to the question 'Install any extra modules?' and
 1443 then answer "Bundle::LWP DBI" to the 'Extras?' question.
 1444 The module or the bundle names are as for the CPAN module 'install'
 1445 command.  This will only work if those modules are to be built as dynamic
 1446 extensions.  If you wish to include those extra modules as static
 1447 extensions, see L<"Extensions"> above.
 1449 Notice that because the CPAN module will be used to fetch the extra
 1450 modules, you will need access to the CPAN, either via the Internet,
 1451 or via a local copy such as a CD-ROM or a local CPAN mirror.  If you
 1452 do not, using the extra modules option will die horribly.
 1454 Also notice that you yourself are responsible for satisfying any extra
 1455 dependencies such as external headers or libraries BEFORE trying the
 1456 build.  For example: you will need to have the Foo database specific
 1457 headers and libraries installed for the DBD::Foo module.  The Configure
 1458 process or the Perl build process will not help you with these.
 1460 =head2 suidperl
 1462 suidperl was an optional component of earlier releases of perl. It is no
 1463 longer available.  Instead, use a tool specifically designed to handle
 1464 changes in privileges, such as B<sudo>.
 1466 =head1 make depend
 1468 This will look for all the includes.  The output is stored in makefile.
 1469 The only difference between Makefile and makefile is the dependencies at
 1470 the bottom of makefile.  If you have to make any changes, you should edit
 1471 makefile, not Makefile, since the Unix make command reads makefile first.
 1472 (On non-Unix systems, the output may be stored in a different file.
 1473 Check the value of $firstmakefile in your config.sh if in doubt.)
 1475 Configure will offer to do this step for you, so it isn't listed
 1476 explicitly above.
 1478 =head1 make
 1480 This will attempt to make perl in the current directory.
 1482 =head2 Expected errors
 1484 These error reports are normal, and can be ignored:
 1486   ...
 1487   make: [extra.pods] Error 1 (ignored)
 1488   ...
 1489   make: [extras.make] Error 1 (ignored)
 1491 =head2 What if it doesn't work?
 1493 If you can't compile successfully, try some of the following ideas.
 1494 If none of them help, and careful reading of the error message and
 1495 the relevant manual pages on your system doesn't help,
 1496 then see L<"Reporting Problems"> below.
 1498 =over 4
 1500 =item hints
 1502 If you used a hint file, try reading the comments in the hint file
 1503 for further tips and information.
 1505 =item extensions
 1507 If you can successfully build miniperl, but the process crashes
 1508 during the building of extensions, run
 1510 	make minitest
 1512 to test your version of miniperl.
 1514 =item locale
 1516 If you have any locale-related environment variables set, try unsetting
 1517 them.  I have some reports that some versions of IRIX hang while
 1518 running B<./miniperl configpm> with locales other than the C locale.
 1519 See the discussion under L<"make test"> below about locales and the
 1520 whole L<perllocale/"LOCALE PROBLEMS"> section in the file
 1521 pod/perllocale.pod.  The latter is especially useful if you see something
 1522 like this
 1524 	perl: warning: Setting locale failed.
 1525 	perl: warning: Please check that your locale settings:
 1526 	        LC_ALL = "En_US",
 1527 	        LANG = (unset)
 1528 	    are supported and installed on your system.
 1529 	perl: warning: Falling back to the standard locale ("C").
 1531 at Perl startup.
 1533 =item other environment variables
 1535 Configure does not check for environment variables that can sometimes
 1536 have a major influence on how perl is built or tested. For example,
 1537 OBJECT_MODE on AIX determines the way the compiler and linker deal with
 1538 their objects, but this is a variable that only influences build-time
 1539 behaviour, and should not affect the perl scripts that are eventually
 1540 executed by the perl binary. Other variables, like PERL_UNICODE,
 1541 PERL5LIB, and PERL5OPT will influence the behaviour of the test suite.
 1542 So if you are getting strange test failures, you may want to try
 1543 retesting with the various PERL variables unset.
 1545 =item LD_LIBRARY_PATH
 1547 If you run into dynamic loading problems, check your setting of
 1548 the LD_LIBRARY_PATH environment variable.  If you're creating a static
 1549 Perl library (libperl.a rather than libperl.so) it should build
 1550 fine with LD_LIBRARY_PATH unset, though that may depend on details
 1551 of your local setup.
 1553 =item nm extraction
 1555 If Configure seems to be having trouble finding library functions,
 1556 try not using nm extraction.  You can do this from the command line
 1557 with
 1559 	sh Configure -Uusenm
 1561 or by answering the nm extraction question interactively.
 1562 If you have previously run Configure, you should not reuse your old
 1563 config.sh.
 1565 =item umask not found
 1567 If the build processes encounters errors relating to umask(), the problem
 1568 is probably that Configure couldn't find your umask() system call.
 1569 Check your config.sh.  You should have d_umask='define'.  If you don't,
 1570 this is probably the L<"nm extraction"> problem discussed above.  Also,
 1571 try reading the hints file for your system for further information.
 1573 =item do_aspawn
 1575 If you run into problems relating to do_aspawn or do_spawn, the
 1576 problem is probably that Configure failed to detect your system's
 1577 fork() function.  Follow the procedure in the previous item
 1578 on L<"nm extraction">.
 1580 =item __inet_* errors
 1582 If you receive unresolved symbol errors during Perl build and/or test
 1583 referring to __inet_* symbols, check to see whether BIND 8.1 is
 1584 installed.  It installs a /usr/local/include/arpa/inet.h that refers to
 1585 these symbols.  Versions of BIND later than 8.1 do not install inet.h
 1586 in that location and avoid the errors.  You should probably update to a
 1587 newer version of BIND (and remove the files the old one left behind).
 1588 If you can't, you can either link with the updated resolver library
 1589 provided with BIND 8.1 or rename /usr/local/bin/arpa/inet.h during the
 1590 Perl build and test process to avoid the problem.
 1592 =item .*_r() prototype NOT found
 1594 On a related note, if you see a bunch of complaints like the above about
 1595 reentrant functions -- specifically networking-related ones -- being
 1596 present but without prototypes available, check to see if BIND 8.1 (or
 1597 possibly other BIND 8 versions) is (or has been) installed. They install
 1598 header files such as netdb.h into places such as /usr/local/include (or
 1599 into another directory as specified at build/install time), at least
 1600 optionally.  Remove them or put them in someplace that isn't in the C
 1601 preprocessor's header file include search path (determined by -I options
 1602 plus defaults, normally /usr/include).
 1604 =item #error "No DATAMODEL_NATIVE specified"
 1606 This is a common error when trying to build perl on Solaris 2.6 with a
 1607 gcc installation from Solaris 2.5 or 2.5.1.  The Solaris header files
 1608 changed, so you need to update your gcc installation.  You can either
 1609 rerun the fixincludes script from gcc or take the opportunity to
 1610 update your gcc installation.
 1612 =item Optimizer
 1614 If you can't compile successfully, try turning off your compiler's
 1615 optimizer.  Edit config.sh and change the line
 1617 	optimize='-O'
 1619 to
 1621 	optimize=' '
 1623 then propagate your changes with B<sh Configure -S> and rebuild
 1624 with B<make depend; make>.
 1626 =item Missing functions and Undefined symbols
 1628 If the build of miniperl fails with a long list of missing functions or
 1629 undefined symbols, check the libs variable in the config.sh file.  It
 1630 should look something like
 1632 	libs='-lsocket -lnsl -ldl -lm -lc'
 1634 The exact libraries will vary from system to system, but you typically
 1635 need to include at least the math library -lm.  Normally, Configure
 1636 will suggest the correct defaults.  If the libs variable is empty, you
 1637 need to start all over again.  Run
 1639 	make distclean
 1641 and start from the very beginning.  This time, unless you are sure of
 1642 what you are doing, accept the default list of libraries suggested by
 1643 Configure.
 1645 If the libs variable is missing -lm, there is a chance that libm.so.1
 1646 is available, but the required (symbolic) link to libm.so is missing.
 1647 (same could be the case for other libraries like libcrypt.so).  You
 1648 should check your installation for packages that create that link, and
 1649 if no package is installed that supplies that link or you cannot install
 1650 them, make the symbolic link yourself e.g.:
 1652  $ rpm -qf /usr/lib64/libm.so
 1653  glibc-devel-2.15-22.17.1.x86_64
 1654  $ ls -lgo /usr/lib64/libm.so
 1655  lrwxrwxrwx 1 16 Jan  7  2013 /usr/lib64/libm.so -> /lib64/libm.so.6
 1657  or
 1659  $ sudo ln -s /lib64/libm.so.6 /lib64/libm.so
 1661 If the libs variable looks correct, you might have the
 1662 L<"nm extraction"> problem discussed above.
 1664 If you still have missing routines or undefined symbols, you probably
 1665 need to add some library or other, make a symbolic link like described
 1666 above, or you need to undefine some feature that Configure thought was
 1667 there but is defective or incomplete.  If you used a hint file, see if
 1668 it has any relevant advice.  You can also look through config.h
 1669 for likely suspects.
 1671 =item toke.c
 1673 Some compilers will not compile or optimize the larger files (such as
 1674 toke.c) without some extra switches to use larger jump offsets or
 1675 allocate larger internal tables.  You can customize the switches for
 1676 each file in cflags.SH.  It's okay to insert rules for specific files
 1677 into makefile since a default rule only takes effect in the absence of a
 1678 specific rule.
 1680 =item Missing dbmclose
 1682 SCO prior to 3.2.4 may be missing dbmclose().  An upgrade to 3.2.4
 1683 that includes libdbm.nfs (which includes dbmclose()) may be available.
 1685 =item error: too few arguments to function 'dbmclose'
 1687 Building ODBM_File on some (Open)SUSE distributions might run into this
 1688 error, as the header file is broken. There are two ways to deal with this
 1690  1. Disable the use of ODBM_FILE
 1692     sh Configure ... -Dnoextensions=ODBM_File
 1694  2. Fix the header file, somewhat like this:
 1696     --- a/usr/include/dbm.h  2010-03-24 08:54:59.000000000 +0100
 1697     +++ b/usr/include/dbm.h  2010-03-24 08:55:15.000000000 +0100
 1698     @@ -59,4 +59,4 @@ extern datum  firstkey __P((void));
 1700      extern datum   nextkey __P((datum key));
 1702     -extern int     dbmclose __P((DBM *));
 1703     +extern int     dbmclose __P((void));
 1705 =item Warning (mostly harmless): No library found for -lsomething
 1707 If you see such a message during the building of an extension, but
 1708 the extension passes its tests anyway (see L<"make test"> below),
 1709 then don't worry about the warning message.  The extension
 1710 Makefile.PL goes looking for various libraries needed on various
 1711 systems; few systems will need all the possible libraries listed.
 1712 Most users will see warnings for the ones they don't have.  The
 1713 phrase 'mostly harmless' is intended to reassure you that nothing
 1714 unusual is happening, and the build process is continuing.
 1716 On the other hand, if you are building GDBM_File and you get the
 1717 message
 1719     Warning (mostly harmless): No library found for -lgdbm
 1721 then it's likely you're going to run into trouble somewhere along
 1722 the line, since it's hard to see how you can use the GDBM_File
 1723 extension without the -lgdbm library.
 1725 It is true that, in principle, Configure could have figured all of
 1726 this out, but Configure and the extension building process are not
 1727 quite that tightly coordinated.
 1729 =item sh: ar: not found
 1731 This is a message from your shell telling you that the command 'ar'
 1732 was not found.  You need to check your PATH environment variable to
 1733 make sure that it includes the directory with the 'ar' command.  This
 1734 is a common problem on Solaris, where 'ar' is in the /usr/ccs/bin
 1735 directory.
 1737 =item db-recno failure on tests 51, 53 and 55
 1739 Old versions of the DB library (including the DB library which comes
 1740 with FreeBSD 2.1) had broken handling of recno databases with modified
 1741 bval settings.  Upgrade your DB library or OS.
 1743 =item Bad arg length for semctl, is XX, should be ZZZ
 1745 If you get this error message from the F<cpan/IPC-SysV/t/sem.t> test, your
 1746 System V IPC may be broken.  The XX typically is 20, and that is what ZZZ
 1747 also should be.  Consider upgrading your OS, or reconfiguring your OS
 1748 to include the System V semaphores.
 1750 =item cpan/IPC-SysV/t/sem........semget: No space left on device
 1752 Either your account or the whole system has run out of semaphores.  Or
 1753 both.  Either list the semaphores with "ipcs" and remove the unneeded
 1754 ones (which ones these are depends on your system and applications)
 1755 with "ipcrm -s SEMAPHORE_ID_HERE" or configure more semaphores to your
 1756 system.
 1758 =item GNU binutils
 1760 If you mix GNU binutils (nm, ld, ar) with equivalent vendor-supplied
 1761 tools you may be in for some trouble.  For example creating archives
 1762 with an old GNU 'ar' and then using a new current vendor-supplied 'ld'
 1763 may lead into linking problems.  Either recompile your GNU binutils
 1764 under your current operating system release, or modify your PATH not
 1765 to include the GNU utils before running Configure, or specify the
 1766 vendor-supplied utilities explicitly to Configure, for example by
 1767 Configure -Dar=/bin/ar.
 1771 The F<Configure> program has not been able to find all the files which
 1772 make up the complete Perl distribution.  You may have a damaged source
 1773 archive file (in which case you may also have seen messages such as
 1774 C<gzip: stdin: unexpected end of file> and C<tar: Unexpected EOF on
 1775 archive file>), or you may have obtained a structurally-sound but
 1776 incomplete archive.  In either case, try downloading again from the
 1777 official site named at the start of this document.  If you do find
 1778 that any site is carrying a corrupted or incomplete source code
 1779 archive, please report it to the site's maintainer.
 1781 =item invalid token: ##
 1783 You are using a non-ANSI-compliant C compiler.  To compile Perl, you
 1784 need to use a compiler that supports ANSI C.  If there is a README
 1785 file for your system, it may have further details on your compiler
 1786 options.
 1788 =item Miscellaneous
 1790 Some additional things that have been reported:
 1792 Genix may need to use libc rather than libc_s, or #undef VARARGS.
 1794 NCR Tower 32 (OS 2.01.01) may need -W2,-Sl,2000 and #undef MKDIR.
 1796 UTS may need one or more of -K or -g, and #undef LSTAT.
 1798 FreeBSD can fail the F<cpan/IPC-SysV/t/sem.t> test if SysV IPC has not been
 1799 configured in the kernel.  Perl tries to detect this, though, and
 1800 you will get a message telling you what to do.
 1802 Building Perl on a system that has also BIND (headers and libraries)
 1803 installed may run into troubles because BIND installs its own netdb.h
 1804 and socket.h, which may not agree with the operating system's ideas of
 1805 the same files.  Similarly, including -lbind may conflict with libc's
 1806 view of the world.  You may have to tweak -Dlocincpth and -Dloclibpth
 1807 to avoid the BIND.
 1809 =back
 1811 =head2 Cross-compilation
 1813 Perl can be cross-compiled.  It is just not trivial, cross-compilation
 1814 rarely is.  Perl is routinely cross-compiled for several platforms: as of
 1815 June 2019, these include Android, Blackberry 10,
 1816 ARM Linux, and Solaris.  Previous versions of
 1817 Perl also provided support for Open Zaurus, Symbian, and
 1818 the IBM OS/400, but it's unknown if those ports are still functional.
 1819 These platforms are known as the B<target> platforms, while the systems
 1820 where the compilation takes place are the B<host> platforms.
 1822 What makes the situation difficult is that first of all,
 1823 cross-compilation environments vary significantly in how they are set
 1824 up and used, and secondly because the primary way of configuring Perl
 1825 (using the rather large Unix-tool-dependent Configure script) is not
 1826 awfully well suited for cross-compilation.  However, starting from
 1827 version 5.18.0, the Configure script also knows two ways of supporting
 1828 cross-compilation, so please keep reading.
 1830 See the following files for more information about compiling Perl for
 1831 the particular platforms:
 1833 =over 4
 1835 =item Android
 1837 L<"Cross-compilation" in README.android or
 1838 perlandroid|perlandroid/Cross-compilation>
 1840 =item Blackberry
 1842 L<"Cross-compilation" in README.qnx or perlqnx|perlqnx/Cross-compilation>
 1844 =item Solaris
 1846 L<"CROSS-COMPILATION" in README.solaris or
 1847 perlsolaris|perlsolaris/CROSS-COMPILATION>
 1849 =item Linux
 1851 This document; See below.
 1853 =back
 1855 Packaging and transferring either the core Perl modules or CPAN
 1856 modules to the target platform is also left up to the each
 1857 cross-compilation environment.  Often the cross-compilation target
 1858 platforms are somewhat limited in diskspace: see the section
 1859 L</Minimizing the Perl installation> to learn more of the minimal set
 1860 of files required for a functional Perl installation.
 1862 For some cross-compilation environments the Configure option
 1863 C<-Dinstallprefix=...> might be handy, see L</Changing the installation
 1864 directory>.
 1866 About the cross-compilation support of Configure: There's two forms.
 1867 The more common one requires some way of transferring and running
 1868 executables in the target system, such as an ssh connection; this is the
 1869 C<./Configure -Dusecrosscompile -Dtargethost=...> route.  The second
 1870 method doesn't need access to the target system, but requires you to
 1871 provide a config.sh, and a canned Makefile; the rest of this section
 1872 describes the former.
 1874 This cross-compilation setup of Configure has successfully been used in
 1875 a wide variety of setups, such as a 64-bit OS X host for an Android ARM
 1876 target, or an amd64 Linux host targeting x86 Solaris, or even Windows.
 1878 To run Configure in cross-compilation mode the basic switch that
 1879 has to be used is C<-Dusecrosscompile>:
 1881    sh ./Configure -des -Dusecrosscompile -D...
 1883 This will make the cpp symbol USE_CROSS_COMPILE and the %Config
 1884 symbol C<usecrosscompile> available.
 1886 During the Configure and build, certain helper scripts will be created
 1887 into the Cross/ subdirectory.  The scripts are used to execute a
 1888 cross-compiled executable, and to transfer files to and from the
 1889 target host.  The execution scripts are named F<run-*> and the
 1890 transfer scripts F<to-*> and F<from-*>.  The part after the dash is
 1891 the method to use for remote execution and transfer: by default the
 1892 methods are B<ssh> and B<scp>, thus making the scripts F<run-ssh>,
 1893 F<to-scp>, and F<from-scp>.
 1895 To configure the scripts for a target host and a directory (in which
 1896 the execution will happen and which is to and from where the transfer
 1897 happens), supply Configure with
 1899     -Dtargethost=so.me.ho.st -Dtargetdir=/tar/get/dir
 1901 The targethost is what e.g. ssh will use as the hostname, the targetdir
 1902 must exist (the scripts won't create it), the targetdir defaults to /tmp.
 1903 You can also specify a username to use for ssh/rsh logins
 1905     -Dtargetuser=luser
 1907 but in case you don't, "root" will be used.  Similarly, you can specify
 1908 a non-standard (i.e. not 22) port for the connection, if applicable,
 1909 through
 1911     -Dtargetport=2222
 1913 If the name of C<cc> has the usual GNU C semantics for cross
 1914 compilers, that is, CPU-OS-gcc, the target architecture (C<targetarch>),
 1915 plus names of the C<ar>, C<nm>, and C<ranlib> will also be automatically
 1916 chosen to be CPU-OS-ar and so on.
 1917 (The C<ld> requires more thought and will be chosen later by Configure
 1918 as appropriate).  This will also aid in guessing the proper
 1919 operating system name for the target, which has other repercussions, like
 1920 better defaults and possibly critical fixes for the platform.  If
 1921 Configure isn't guessing the OS name properly, you may need to either add
 1922 a hint file redirecting Configure's guess, or modify Configure to make
 1923 the correct choice.
 1925 If your compiler doesn't follow that convention, you will also need to
 1926 specify which target environment to use, as well as C<ar> and friends:
 1928     -Dtargetarch=arm-linux
 1929     -Dcc=mycrossgcc
 1930     -Dar=...
 1932 Additionally, a cross-compilation toolchain will usually install it's own
 1933 logical system root somewhere -- that is, it'll create a directory
 1934 somewhere which includes subdirectories like C<'include'> or C<'lib'>.  For
 1935 example, you may end up with F</skiff/local/arm-linux>, where
 1936 F</skiff/local/arm-linux/bin> holds the binaries for cross-compilation,
 1937 F</skiff/local/arm-linux/include> has the headers, and
 1938 F</skiff/local/arm-linux/lib> has the library files.
 1939 If this is the case, and you are using a compiler that understands
 1940 C<--sysroot>, like gcc or clang, you'll want to specify the
 1941 C<-Dsysroot> option for Configure:
 1943     -Dsysroot=/skiff/local/arm-linux
 1945 However, if your don't have a suitable directory to pass to C<-Dsysroot>,
 1946 you will also need to specify which target environment to use:
 1948     -Dusrinc=/skiff/local/arm-linux/include
 1949     -Dincpth=/skiff/local/arm-linux/include
 1950     -Dlibpth=/skiff/local/arm-linux/lib
 1952 In addition to the default execution/transfer methods you can also
 1953 choose B<rsh> for execution, and B<rcp> or B<cp> for transfer,
 1954 for example:
 1956     -Dtargetrun=rsh -Dtargetto=rcp -Dtargetfrom=cp
 1958 Putting it all together:
 1960     sh ./Configure -des -Dusecrosscompile \
 1961         -Dtargethost=so.me.ho.st \
 1962         -Dtargetdir=/tar/get/dir \
 1963         -Dtargetuser=root \
 1964         -Dtargetarch=arm-linux \
 1965         -Dcc=arm-linux-gcc \
 1966         -Dsysroot=/skiff/local/arm-linux \
 1967         -D...
 1969 or if you are happy with the defaults:
 1971     sh ./Configure -des -Dusecrosscompile \
 1972         -Dtargethost=so.me.ho.st \
 1973         -Dcc=arm-linux-gcc \
 1974         -D...
 1976 Another example where the cross-compiler has been installed under
 1977 F</usr/local/arm/2.95.5>:
 1979     sh ./Configure -des -Dusecrosscompile \
 1980         -Dtargethost=so.me.ho.st \
 1981         -Dcc=/usr/local/arm/2.95.5/bin/arm-linux-gcc \
 1982         -Dsysroot=/usr/local/arm/2.95.5
 1984 There is also a C<targetenv> option for Configure which can be used
 1985 to modify the environment of the target just before testing begins
 1986 during 'make test'.  For example, if the target system has a nonstandard
 1987 /tmp location, you could do this:
 1989     -Dtargetenv="export TMPDIR=/other/tmp;"
 1991 If you are planning on cross-compiling to several platforms, or some
 1992 other thing that would involve running Configure several times, there are
 1993 two options that can be used to speed things up considerably.
 1994 As a bit of background, when you
 1995 call Configure with C<-Dusecrosscompile>, it begins by actually partially
 1996 building a miniperl on the host machine, as well as the generate_uudmap
 1997 binary, and we end up using that during the build.
 1998 So instead of building that new perl every single time, you can build it
 1999 just once in a separate directory, and then pass the resulting binaries
 2000 to Configure like this:
 2002     -Dhostperl=/path/to/second/build/dir/miniperl
 2003     -Dhostgenerate=/path/to/second/build/dir/generate_uudmap
 2005 Much less commonly, if you are cross-compiling from an ASCII host to an
 2006 EBCDIC target, or vise versa, you'll have to pass C<-Uhostgenerate> to
 2007 Configure, to signify that you want to build a generate_uudmap binary
 2008 that, during make, will be run on the target system.
 2010 =head1 make test
 2012 This will run the regression tests on the perl you just made.  If
 2013 'make test' doesn't say "All tests successful" then something went
 2014 wrong.
 2016 Note that you can't run the tests in background if this disables
 2017 opening of /dev/tty. You can use 'make test-notty' in that case but
 2018 a few tty tests will be skipped.
 2020 =head2 What if make test doesn't work?
 2022 If make test bombs out, just cd to the t directory and run ./TEST
 2023 by hand to see if it makes any difference.
 2025 One way to get more detailed information about failed tests and
 2026 individual subtests is to run the harness from the t directory:
 2028 	cd t ; ./perl harness <list of tests>
 2030 (this assumes that most basic tests succeed, since harness uses
 2031 complicated constructs). If no list of tests is provided, harness
 2032 will run all tests.
 2034 If individual tests fail, you can often run them by hand (from the main
 2035 perl directory), e.g.,
 2037 	./perl -I. -MTestInit t/op/groups.t
 2039 You should also read the individual tests to see if there are any helpful
 2040 comments that apply to your system.  You may also need to setup your
 2041 shared library path if you get errors like:
 2043 	/sbin/loader: Fatal Error: cannot map libperl.so
 2045 The file t/README in the t subdirectory contains more information about
 2046 running and modifying tests.
 2048 See L</"Building a shared Perl library"> earlier in this document.
 2050 =over 4
 2052 =item locale
 2054 Note:  One possible reason for errors is that some external programs
 2055 may be broken due to the combination of your environment and the way
 2056 'make test' exercises them.  For example, this may happen if you have
 2057 one or more of these environment variables set:  LC_ALL LC_CTYPE
 2058 LC_COLLATE LANG.  In some versions of UNIX, the non-English locales
 2059 are known to cause programs to exhibit mysterious errors.
 2061 If you have any of the above environment variables set, please try
 2063 	setenv LC_ALL C
 2065 (for C shell) or
 2067 	LC_ALL=C;export LC_ALL
 2069 for Bourne or Korn shell) from the command line and then retry
 2070 make test.  If the tests then succeed, you may have a broken program that
 2071 is confusing the testing.  Please run the troublesome test by hand as
 2072 shown above and see whether you can locate the program.  Look for
 2073 things like:  exec, `backquoted command`, system, open("|...") or
 2074 open("...|").  All these mean that Perl is trying to run some
 2075 external program.
 2077 =item Timing problems
 2079 Several tests in the test suite check timing functions, such as
 2080 sleep(), and see if they return in a reasonable amount of time.
 2081 If your system is quite busy and doesn't respond quickly enough,
 2082 these tests might fail.  If possible, try running the tests again
 2083 with the system under a lighter load.  These timing-sensitive
 2084 and load-sensitive tests include F<t/op/alarm.t>,
 2085 F<dist/Time-HiRes/t/alarm.t>, F<dist/Time-HiRes/t/clock.t>,
 2086 F<dist/Time-HiRes/t/itimer.t>, F<dist/Time-HiRes/t/usleep.t>,
 2087 F<dist/threads-shared/t/waithires.t>,
 2088 F<dist/threads-shared/t/stress.t>, F<lib/Benchmark.t>,
 2089 F<lib/Memoize/t/expmod_t.t>, and F<lib/Memoize/t/speed.t>.
 2091 You might also experience some failures in F<t/op/stat.t> if you build
 2092 perl on an NFS filesystem, if the remote clock and the system clock are
 2093 different.
 2095 =item Out of memory
 2097 On some systems, particularly those with smaller amounts of RAM, some
 2098 of the tests in t/op/pat.t may fail with an "Out of memory" message.
 2099 For example, on my SparcStation IPC with 12 MB of RAM, in perl5.5.670,
 2100 test 85 will fail if run under either t/TEST or t/harness.
 2102 Try stopping other jobs on the system and then running the test by itself:
 2104 	./perl -I. -MTestInit t/op/pat.t
 2106 to see if you have any better luck.  If your perl still fails this
 2107 test, it does not necessarily mean you have a broken perl.  This test
 2108 tries to exercise the regular expression subsystem quite thoroughly,
 2109 and may well be far more demanding than your normal usage.
 2111 =item libgcc_s.so.1: cannot open shared object file
 2113 This message has been reported on gcc-3.2.3 and earlier installed with
 2114 a non-standard prefix.  Setting the LD_LIBRARY_PATH environment variable
 2115 (or equivalent) to include gcc's lib/ directory with the libgcc_s.so.1
 2116 shared library should fix the problem.
 2118 =item Failures from lib/File/Temp/t/security saying "system possibly insecure"
 2120 First, such warnings are not necessarily serious or indicative of a
 2121 real security threat.  That being said, they bear investigating.
 2123 Note that each of the tests is run twice.  The first time is in the
 2124 directory returned by File::Spec->tmpdir() (often /tmp on Unix
 2125 systems), and the second time in the directory from which the test was
 2126 run (usually the 't' directory, if the test was run as part of 'make
 2127 test').
 2129 The tests may fail for the following reasons:
 2131 (1) If the directory the tests are being run in is owned by somebody
 2132 other than the user running the tests, or by root (uid 0).
 2134 This failure can happen if the Perl source code distribution is
 2135 unpacked in such a way that the user IDs in the distribution package
 2136 are used as-is.  Some tar programs do this.
 2138 (2) If the directory the tests are being run in is writable by group or
 2139 by others, and there is no sticky bit set for the directory.  (With
 2140 UNIX/POSIX semantics, write access to a directory means the right to
 2141 add or remove files in that directory.  The 'sticky bit' is a feature
 2142 used in some UNIXes to give extra protection to files: if the bit is
 2143 set for a directory, no one but the owner (or root) can remove that
 2144 file even if the permissions would otherwise allow file removal by
 2145 others.)
 2147 This failure may or may not be a real problem: it depends on the
 2148 permissions policy used on this particular system.  This failure can
 2149 also happen if the system either doesn't support the sticky bit (this
 2150 is the case with many non-UNIX platforms: in principle File::Temp
 2151 should know about these platforms and skip the tests), or if the system
 2152 supports the sticky bit but for some reason or reasons it is not being
 2153 used.  This is, for example, the case with HP-UX: as of HP-UX release
 2154 11.00, the sticky bit is very much supported, but HP-UX doesn't use it
 2155 on its /tmp directory as shipped.  Also, as with the permissions, some
 2156 local policy might dictate that the stickiness is not used.
 2158 (3) If the system supports the POSIX 'chown giveaway' feature and if
 2159 any of the parent directories of the temporary file back to the root
 2160 directory are 'unsafe', using the definitions given above in (1) and
 2161 (2).  For Unix systems, this is usually not an issue if you are
 2162 building on a local disk.  See the documentation for the File::Temp
 2163 module for more information about 'chown giveaway'.
 2165 See the documentation for the File::Temp module for more information
 2166 about the various security aspects of temporary files.
 2168 =back
 2170 The core distribution can now run its regression tests in parallel on
 2171 Unix-like platforms. Instead of running C<make test>, set C<TEST_JOBS>
 2172 in your environment to the number of tests to run in parallel, and run
 2173 C<make test_harness>. On a Bourne-like shell, this can be done as
 2175     TEST_JOBS=3 make test_harness  # Run 3 tests in parallel
 2177 An environment variable is used, rather than parallel make itself,
 2178 because L<TAP::Harness> needs to be able to schedule individual
 2179 non-conflicting test scripts itself, and there is no standard interface
 2180 to C<make> utilities to interact with their job schedulers.
 2182 =head1 make install
 2184 This will put perl into the public directory you specified to
 2185 Configure; by default this is /usr/local/bin.  It will also try to put
 2186 the man pages in a reasonable place.  It will not nroff the man pages,
 2187 however.  You may need to be root to run B<make install>.  If you are not
 2188 root, you must still have permission to install into the directories
 2189 in question and you should ignore any messages about chown not working.
 2191 If "make install" just says "'install' is up to date" or something
 2192 similar, you may be on a case-insensitive filesystems such as Mac's HFS+,
 2193 and you should say "make install-all".  (This confusion is brought to you
 2194 by the Perl distribution having a file called INSTALL.)
 2196 =head2 Installing perl under different names
 2198 If you want to install perl under a name other than "perl" (for example,
 2199 when installing perl with special features enabled, such as debugging),
 2200 indicate the alternate name on the "make install" line, such as:
 2202     make install PERLNAME=myperl
 2204 You can separately change the base used for versioned names (like
 2205 "perl5.8.9") by setting PERLNAME_VERBASE, like
 2207     make install PERLNAME=perl5 PERLNAME_VERBASE=perl
 2209 This can be useful if you have to install perl as "perl5" (e.g. to avoid
 2210 conflicts with an ancient version in /usr/bin supplied by your vendor).
 2211 Without this the versioned binary would be called "perl55.8.8".
 2213 =head2 Installing perl under a different directory
 2215 You can install perl under a different destination directory by using
 2216 the DESTDIR variable during C<make install>, with a command like
 2218 	make install DESTDIR=/tmp/perl5
 2220 DESTDIR is automatically prepended to all the installation paths.  See
 2221 the example in L<"DESTDIR"> above.
 2223 =head2 Installed files
 2225 If you want to see exactly what will happen without installing
 2226 anything, you can run
 2228 	./perl installperl -n
 2229 	./perl installman -n
 2231 make install will install the following:
 2233     binaries
 2235 	perl,
 2236 	    perl5.n.n	where 5.n.n is the current release number.  This
 2237 			will be a link to perl.
 2239     scripts
 2241 	cppstdin	This is used by the deprecated switch perl -P,
 2242 			if your cc -E can't read from stdin.
 2243 	corelist	Shows versions of modules that come with
 2244                         different
 2245 			versions of perl.
 2246 	cpan		The CPAN shell.
 2247 	enc2xs		Encoding module generator.
 2248 	h2ph		Extract constants and simple macros from C
 2249                         headers.
 2250 	h2xs		Converts C .h header files to Perl extensions.
 2251 	instmodsh	A shell to examine installed modules.
 2252 	libnetcfg	Configure libnet.
 2253 	perlbug		Tool to report bugs in Perl.
 2254 	perldoc		Tool to read perl's pod documentation.
 2255 	perlivp		Perl Installation Verification Procedure.
 2256 	piconv		A Perl implementation of the encoding conversion
 2257 			utility iconv.
 2258 	pl2pm		Convert Perl 4 .pl files to Perl 5 .pm modules.
 2259 	pod2html,	Converters from perl's pod documentation format
 2260 	pod2man,
 2261 	pod2text,
 2262 	pod2usage
 2263 	podchecker	POD syntax checker.
 2264 	podselect	Prints sections of POD documentation.
 2265 	prove		A command-line tool for running tests.
 2266 	psed		A Perl implementation of sed.
 2267 	ptar		A Perl implementation of tar.
 2268 	ptardiff	A diff for tar archives.
 2269 	ptargrep	A grep for tar archives.
 2270 	shasum		A tool to print or check SHA checksums.
 2271 	splain		Describe Perl warnings and errors.
 2272 	xsubpp		Compiler to convert Perl XS code into C code.
 2273 	zipdetails	display the internal structure of zip files
 2275     library files
 2277 			in $privlib and $archlib specified to
 2278 			Configure, usually under /usr/local/lib/perl5/.
 2280     documentation
 2282 	man pages	in $man1dir, usually /usr/local/man/man1.
 2283 	module man
 2284 	pages		in $man3dir, usually /usr/local/man/man3.
 2285 	pod/*.pod	in $privlib/pod/.
 2287 installperl will also create the directories listed above
 2288 in L<"Installation Directories">.
 2290 Perl's *.h header files and the libperl library are also installed
 2291 under $archlib so that any user may later build new modules, run the
 2292 optional Perl compiler, or embed the perl interpreter into another
 2293 program even if the Perl source is no longer available.
 2295 =head2 Installing with a version-specific suffix
 2297 Sometimes you only want to install the perl distribution with a
 2298 version-specific suffix.  For example, you may wish to install a newer
 2299 version of perl alongside an already installed production version.
 2300 To only install the version-specific parts of the perl installation, run
 2302 	Configure -Dversiononly
 2304 or answer 'y' to the appropriate Configure prompt.  Alternatively,
 2305 you can just manually run
 2307 	./perl installperl -v
 2309 and skip installman altogether.
 2311 See also L<"Maintaining completely separate versions"> for another
 2312 approach.
 2314 =head1 cd /usr/include; h2ph *.h sys/*.h
 2316 Some perl scripts need to be able to obtain information from the
 2317 system header files.  This command will convert the most commonly used
 2318 header files in /usr/include into files that can be easily interpreted
 2319 by perl.  These files will be placed in the architecture-dependent
 2320 library ($archlib) directory you specified to Configure.
 2322 Note: Due to differences in the C and perl languages, the conversion
 2323 of the header files is not perfect.  You will probably have to
 2324 hand-edit some of the converted files to get them to parse correctly.
 2325 For example, h2ph breaks spectacularly on type casting and certain
 2326 structures.
 2328 =head1 installhtml --help
 2330 Some sites may wish to make perl documentation available in HTML
 2331 format.  The installhtml utility can be used to convert pod
 2332 documentation into linked HTML files and install them.
 2334 Currently, the supplied ./installhtml script does not make use of the
 2335 html Configure variables.  This should be fixed in a future release.
 2337 The following command-line is an example of one used to convert
 2338 perl documentation:
 2340   ./installhtml                   \
 2341       --podroot=.                 \
 2342       --podpath=lib:ext:pod:vms   \
 2343       --recurse                   \
 2344       --htmldir=/perl/nmanual     \
 2345       --htmlroot=/perl/nmanual    \
 2346       --splithead=pod/perlipc     \
 2347       --splititem=pod/perlfunc    \
 2348       --verbose
 2350 See the documentation in installhtml for more details.  It can take
 2351 many minutes to execute a large installation and you should expect to
 2352 see warnings like "no title", "unexpected directive" and "cannot
 2353 resolve" as the files are processed. We are aware of these problems
 2354 (and would welcome patches for them).
 2356 You may find it helpful to run installhtml twice. That should reduce
 2357 the number of "cannot resolve" warnings.
 2359 =head1 cd pod && make tex && (process the latex files)
 2361 Some sites may also wish to make the documentation in the pod/ directory
 2362 available in TeX format.  Type
 2364 	(cd pod && make tex && <process the latex files>)
 2366 =head1 Starting all over again
 2368 If you wish to rebuild perl from the same build directory, you should
 2369 clean it out with the command
 2371 	make distclean
 2373 or
 2375 	make realclean
 2377 The only difference between the two is that make distclean also removes
 2378 your old config.sh and Policy.sh files.  (A plain 'make clean' is now
 2379 equivalent to 'make realclean'.)
 2381 If you are upgrading from a previous version of perl, or if you
 2382 change systems or compilers or make other significant changes, or if
 2383 you are experiencing difficulties building perl, you should not reuse
 2384 your old config.sh.
 2386 If your reason to reuse your old config.sh is to save your particular
 2387 installation choices, then you can probably achieve the same effect by
 2388 using the Policy.sh file.  See the section on L<"Site-wide Policy
 2389 settings"> above.
 2391 =head1 Reporting Problems
 2393 Please report problems to the GitHub issue tracker at
 2394 https://github.com/Perl/perl5/issues, which will ask for the
 2395 appropriate summary configuration information about your perl, which
 2396 may help us track down problems far more quickly.  But first you should
 2397 read the advice in this file, carefully re-read the error message and
 2398 check the relevant manual pages on your system, as these may help you
 2399 find an immediate solution.  Once you've exhausted the documentation,
 2400 please report bugs to us using the GitHub tracker.
 2402 The summary configuration information can be printed with C<perl -V>.
 2403 If the install fails, or you want to report problems with C<make test>
 2404 without installing perl, then you can run it by hand from this source
 2405 directory with C<./perl -V>.
 2407 If the build fails too early to run perl, then please
 2408 B<run> the C<./myconfig> shell script, and include its output along
 2409 with an accurate description of your problem.
 2411 If Configure itself fails, and does not generate a config.sh file
 2412 (needed to run C<./myconfig>), then please open an issue with the
 2413 description of how Configure fails along with details of your system
 2414 -- for example the output from running C<uname -a>.
 2416 Please try to make your message brief but clear.  Brief, clear bug
 2417 reports tend to get answered more quickly.  Please don't worry if your
 2418 written English is not great -- what matters is how well you describe
 2419 the important technical details of the problem you have encountered,
 2420 not whether your grammar and spelling is flawless.
 2422 Trim out unnecessary information.  Do not include large files (such as
 2423 config.sh or a complete Configure or make log) unless absolutely
 2424 necessary.  Do not include a complete transcript of your build
 2425 session.  Just include the failing commands, the relevant error
 2426 messages, and whatever preceding commands are necessary to give the
 2427 appropriate context.
 2429 If the bug you are reporting has security implications which make it
 2430 inappropriate to send to a public issue tracker, then see
 2432 for details of how to report the issue.
 2434 If you are unsure what makes a good bug report please read "How to
 2435 report Bugs Effectively" by Simon Tatham:
 2436 L<https://www.chiark.greenend.org.uk/~sgtatham/bugs.html>
 2438 =head1 Coexistence with earlier versions of perl 5
 2440 Perl 5.32.1 is not binary compatible with versions of Perl earlier than
 2441 5.32.0.
 2442 In other words, you will have to recompile your XS modules.
 2444 In general, you can usually safely upgrade from one stable version of Perl
 2445 (e.g. 5.30.0) to another similar minor version (e.g. 5.30.1) without
 2446 re-compiling all of your extensions.  You can also safely leave the old
 2447 version around in case the new version causes you problems for some
 2448 reason.
 2450 Usually, most extensions will probably not need to be recompiled to be
 2451 used with a newer version of Perl.  Here is how it is supposed to work.
 2452 (These examples assume you accept all the Configure defaults.)
 2454 Suppose you already have version 5.8.7 installed.  The directories
 2455 searched by 5.8.7 are typically like:
 2457 	/usr/local/lib/perl5/5.8.7/$archname
 2458 	/usr/local/lib/perl5/5.8.7
 2459 	/usr/local/lib/perl5/site_perl/5.8.7/$archname
 2460 	/usr/local/lib/perl5/site_perl/5.8.7
 2462 Now, suppose you install version 5.8.8.  The directories
 2463 searched by version 5.8.8 will be:
 2465 	/usr/local/lib/perl5/5.8.8/$archname
 2466 	/usr/local/lib/perl5/5.8.8
 2467 	/usr/local/lib/perl5/site_perl/5.8.8/$archname
 2468 	/usr/local/lib/perl5/site_perl/5.8.8
 2470 	/usr/local/lib/perl5/site_perl/5.8.7/$archname
 2471 	/usr/local/lib/perl5/site_perl/5.8.7
 2472 	/usr/local/lib/perl5/site_perl/
 2474 Notice the last three entries -- Perl understands the default structure
 2475 of the $sitelib directories and will look back in older, compatible
 2476 directories.  This way, modules installed under 5.8.7 will continue
 2477 to be usable by 5.8.7 but will also accessible to 5.8.8.  Further,
 2478 suppose that you upgrade a module to one which requires features
 2479 present only in 5.8.8.  That new module will get installed into
 2480 /usr/local/lib/perl5/site_perl/5.8.8 and will be available to 5.8.8,
 2481 but will not interfere with the 5.8.7 version.
 2483 The last entry, /usr/local/lib/perl5/site_perl/, is there so that
 2484 5.6.0 and above will look for 5.004-era pure perl modules.
 2486 Lastly, suppose you now install 5.10.0, which is not binary compatible
 2487 with 5.8.x.  The directories searched by 5.10.0 (if you don't change the
 2488 Configure defaults) will be:
 2490 	/usr/local/lib/perl5/5.10.0/$archname
 2491 	/usr/local/lib/perl5/5.10.0
 2492 	/usr/local/lib/perl5/site_perl/5.10.0/$archname
 2493 	/usr/local/lib/perl5/site_perl/5.10.0
 2495 	/usr/local/lib/perl5/site_perl/5.8.8
 2497 	/usr/local/lib/perl5/site_perl/5.8.7
 2499 	/usr/local/lib/perl5/site_perl/
 2501 Note that the earlier $archname entries are now gone, but pure perl
 2502 modules from earlier versions will still be found.
 2504 This way, you can choose to share compatible extensions, but also upgrade
 2505 to a newer version of an extension that may be incompatible with earlier
 2506 versions, without breaking the earlier versions' installations.
 2508 =head2 Maintaining completely separate versions
 2510 Many users prefer to keep all versions of perl in completely
 2511 separate directories.  This guarantees that an update to one version
 2512 won't interfere with another version.  (The defaults guarantee this for
 2513 libraries after 5.6.0, but not for executables. TODO?)  One convenient
 2514 way to do this is by using a separate prefix for each version, such as
 2516 	sh Configure -Dprefix=/opt/perl5.32.1
 2518 and adding /opt/perl5.32.1/bin to the shell PATH variable.  Such users
 2519 may also wish to add a symbolic link /usr/local/bin/perl so that
 2520 scripts can still start with #!/usr/local/bin/perl.
 2522 Others might share a common directory for maintenance sub-versions
 2523 (e.g. 5.10 for all 5.10.x versions), but change directory with
 2524 each major version.
 2526 If you are installing a development subversion, you probably ought to
 2527 seriously consider using a separate directory, since development
 2528 subversions may not have all the compatibility wrinkles ironed out
 2529 yet.
 2531 =head2 Upgrading from 5.31.11 or earlier
 2533 B<Perl 5.32.1 may not be binary compatible with Perl 5.31.11 or
 2534 earlier Perl releases.>  Perl modules having binary parts
 2535 (meaning that a C compiler is used) will have to be recompiled to be
 2536 used with 5.32.1.  If you find you do need to rebuild an extension with
 2537 5.32.1, you may safely do so without disturbing the older
 2538 installations.  (See L<"Coexistence with earlier versions of perl 5">
 2539 above.)
 2541 See your installed copy of the perllocal.pod file for a (possibly
 2542 incomplete) list of locally installed modules.  Note that you want
 2543 perllocal.pod, not perllocale.pod, for installed module information.
 2545 =head1 Minimizing the Perl installation
 2547 The following section is meant for people worrying about squeezing the
 2548 Perl installation into minimal systems (for example when installing
 2549 operating systems, or in really small filesystems).
 2551 Leaving out as many extensions as possible is an obvious way:
 2552 Encode, with its big conversion tables, consumes a lot of
 2553 space.  On the other hand, you cannot throw away everything.  The
 2554 Fcntl module is pretty essential.  If you need to do network
 2555 programming, you'll appreciate the Socket module, and so forth: it all
 2556 depends on what do you need to do.
 2558 In the following we offer two different slimmed down installation
 2559 recipes.  They are informative, not normative: the choice of files
 2560 depends on what you need.
 2562 Firstly, the bare minimum to run this script
 2564   use strict;
 2565   use warnings;
 2566   foreach my $f (</*>) {
 2567      print("$f\n");
 2568   }
 2570 in Linux with perl-5.32.1 is as follows (under $Config{prefix}):
 2572   ./bin/perl
 2573   ./lib/perl5/5.32.1/strict.pm
 2574   ./lib/perl5/5.32.1/warnings.pm
 2575   ./lib/perl5/5.32.1/i686-linux/File/Glob.pm
 2576   ./lib/perl5/5.32.1/feature.pm
 2577   ./lib/perl5/5.32.1/XSLoader.pm
 2578   ./lib/perl5/5.32.1/i686-linux/auto/File/Glob/Glob.so
 2580 Secondly, for perl-5.10.1, the Debian perl-base package contains 591
 2581 files, (of which 510 are for lib/unicore) totaling about 3.5MB in its
 2582 i386 version.  Omitting the lib/unicore/* files for brevity, the
 2583 remaining files are:
 2585   /usr/bin/perl
 2586   /usr/bin/perl5.10.1
 2587   /usr/lib/perl/5.10.1/Config.pm
 2588   /usr/lib/perl/5.10.1/Config_git.pl
 2589   /usr/lib/perl/5.10.1/Config_heavy.pl
 2590   /usr/lib/perl/5.10.1/Cwd.pm
 2591   /usr/lib/perl/5.10.1/DynaLoader.pm
 2592   /usr/lib/perl/5.10.1/Errno.pm
 2593   /usr/lib/perl/5.10.1/Fcntl.pm
 2594   /usr/lib/perl/5.10.1/File/Glob.pm
 2595   /usr/lib/perl/5.10.1/Hash/Util.pm
 2596   /usr/lib/perl/5.10.1/IO.pm
 2597   /usr/lib/perl/5.10.1/IO/File.pm
 2598   /usr/lib/perl/5.10.1/IO/Handle.pm
 2599   /usr/lib/perl/5.10.1/IO/Pipe.pm
 2600   /usr/lib/perl/5.10.1/IO/Seekable.pm
 2601   /usr/lib/perl/5.10.1/IO/Select.pm
 2602   /usr/lib/perl/5.10.1/IO/Socket.pm
 2603   /usr/lib/perl/5.10.1/IO/Socket/INET.pm
 2604   /usr/lib/perl/5.10.1/IO/Socket/UNIX.pm
 2605   /usr/lib/perl/5.10.1/List/Util.pm
 2606   /usr/lib/perl/5.10.1/POSIX.pm
 2607   /usr/lib/perl/5.10.1/Scalar/Util.pm
 2608   /usr/lib/perl/5.10.1/Socket.pm
 2609   /usr/lib/perl/5.10.1/XSLoader.pm
 2610   /usr/lib/perl/5.10.1/auto/Cwd/Cwd.so
 2611   /usr/lib/perl/5.10.1/auto/DynaLoader/autosplit.ix
 2612   /usr/lib/perl/5.10.1/auto/DynaLoader/dl_expandspec.al
 2613   /usr/lib/perl/5.10.1/auto/DynaLoader/dl_find_symbol_anywhere.al
 2614   /usr/lib/perl/5.10.1/auto/DynaLoader/dl_findfile.al
 2615   /usr/lib/perl/5.10.1/auto/Fcntl/Fcntl.so
 2616   /usr/lib/perl/5.10.1/auto/File/Glob/Glob.so
 2617   /usr/lib/perl/5.10.1/auto/Hash/Util/Util.so
 2618   /usr/lib/perl/5.10.1/auto/IO/IO.so
 2619   /usr/lib/perl/5.10.1/auto/List/Util/Util.so
 2620   /usr/lib/perl/5.10.1/auto/POSIX/POSIX.so
 2621   /usr/lib/perl/5.10.1/auto/POSIX/autosplit.ix
 2622   /usr/lib/perl/5.10.1/auto/POSIX/load_imports.al
 2623   /usr/lib/perl/5.10.1/auto/Socket/Socket.so
 2624   /usr/lib/perl/5.10.1/lib.pm
 2625   /usr/lib/perl/5.10.1/re.pm
 2626   /usr/share/doc/perl/AUTHORS.gz
 2627   /usr/share/doc/perl/Documentation
 2628   /usr/share/doc/perl/README.Debian
 2629   /usr/share/doc/perl/changelog.Debian.gz
 2630   /usr/share/doc/perl/copyright
 2631   /usr/share/lintian/overrides/perl-base
 2632   /usr/share/man/man1/perl.1.gz
 2633   /usr/share/man/man1/perl5.10.1.1.gz
 2634   /usr/share/perl/5.10.1/AutoLoader.pm
 2635   /usr/share/perl/5.10.1/Carp.pm
 2636   /usr/share/perl/5.10.1/Carp/Heavy.pm
 2637   /usr/share/perl/5.10.1/Exporter.pm
 2638   /usr/share/perl/5.10.1/Exporter/Heavy.pm
 2639   /usr/share/perl/5.10.1/File/Spec.pm
 2640   /usr/share/perl/5.10.1/File/Spec/Unix.pm
 2641   /usr/share/perl/5.10.1/FileHandle.pm
 2642   /usr/share/perl/5.10.1/Getopt/Long.pm
 2643   /usr/share/perl/5.10.1/IPC/Open2.pm
 2644   /usr/share/perl/5.10.1/IPC/Open3.pm
 2645   /usr/share/perl/5.10.1/SelectSaver.pm
 2646   /usr/share/perl/5.10.1/Symbol.pm
 2647   /usr/share/perl/5.10.1/Text/ParseWords.pm
 2648   /usr/share/perl/5.10.1/Text/Tabs.pm
 2649   /usr/share/perl/5.10.1/Text/Wrap.pm
 2650   /usr/share/perl/5.10.1/Tie/Hash.pm
 2651   /usr/share/perl/5.10.1/attributes.pm
 2652   /usr/share/perl/5.10.1/base.pm
 2653   /usr/share/perl/5.10.1/bytes.pm
 2654   /usr/share/perl/5.10.1/bytes_heavy.pl
 2655   /usr/share/perl/5.10.1/constant.pm
 2656   /usr/share/perl/5.10.1/fields.pm
 2657   /usr/share/perl/5.10.1/integer.pm
 2658   /usr/share/perl/5.10.1/locale.pm
 2659   /usr/share/perl/5.10.1/overload.pm
 2660   /usr/share/perl/5.10.1/strict.pm
 2661   /usr/share/perl/5.10.1/unicore/*
 2662   /usr/share/perl/5.10.1/utf8.pm
 2663   /usr/share/perl/5.10.1/utf8_heavy.pl
 2664   /usr/share/perl/5.10.1/vars.pm
 2665   /usr/share/perl/5.10.1/warnings.pm
 2666   /usr/share/perl/5.10.1/warnings/register.pm
 2668 A nice trick to find out the minimal set of Perl library files you will
 2669 need to run a Perl program is
 2671    perl -e 'do "prog.pl"; END { print "$_\n" for sort keys %INC }'
 2673 (this will not find libraries required in runtime, unfortunately, but
 2674 it's a minimal set) and if you want to find out all the files you can
 2675 use something like the below
 2677  strace perl -le 'do "x.pl"' 2>&1 \
 2678                              | perl -nle '/^open\(\"(.+?)"/ && print $1'
 2680 (The 'strace' is Linux-specific, other similar utilities include 'truss'
 2681 and 'ktrace'.)
 2683 =head2 C<-DNO_MATHOMS>
 2685 If you configure perl with C<-Accflags=-DNO_MATHOMS>, the functions from
 2686 F<mathoms.c> will not be compiled in. Those functions are no longer used
 2687 by perl itself; for source compatibility reasons, though, they weren't
 2688 completely removed.
 2693 If you configure perl with C<-Accflags=-DNO_PERL_INTERNAL_RAND_SEED>,
 2694 perl will ignore the C<PERL_INTERNAL_RAND_SEED> environment variable.
 2696 =head1 DOCUMENTATION
 2698 Read the manual entries before running perl.  The main documentation
 2699 is in the F<pod/> subdirectory and should have been installed during the
 2700 build process.  Type B<man perl> to get started.  Alternatively, you
 2701 can type B<perldoc perl> to use the supplied perldoc script.  This is
 2702 sometimes useful for finding things in the library modules.
 2704 =head1 AUTHOR
 2706 Original author:  Andy Dougherty doughera@lafayette.edu , borrowing very
 2707 heavily from the original README by Larry Wall, with lots of helpful
 2708 feedback and additions from the perl5-porters@perl.org folks.
 2710 If you have problems, corrections, or questions, please see
 2711 L<"Reporting Problems"> above.
 2715 This document is part of the Perl package and may be distributed under
 2716 the same terms as perl itself, with the following additional request:
 2717 If you are distributing a modified version of perl (perhaps as part of
 2718 a larger package) please B<do> modify these installation instructions
 2719 and the contact information to match your distribution. Additional
 2720 information for packagers is in F<PACKAGING>.