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Install - Build and Installation guide for perl5.


First, make sure you are installing an up-to-date version of Perl. If you didn't get your Perl source from CPAN, check the latest version at <URL:http://www.cpan.org/src/>.

The basic steps to build and install perl5 on a Unix system with all the defaults are:

        rm -f config.sh Policy.sh
        sh Configure -de
        make test
        make install

        # You may also wish to add these:
        (cd /usr/include && h2ph *.h sys/*.h)
        (installhtml --help)
        (cd pod && make tex  && <process the latex files>)

Each of these is explained in further detail below.

NOTE: starting from the release 5.6.0, Perl uses a version scheme where even-numbered subreleases (like 5.6 and 5.8) are stable maintenance releases and odd-numbered subreleases (like 5.7) are unstable development releases. Development releases should not be used in production environments. Fixes and new features are first carefully tested in development releases and only if they prove themselves to be worthy will they be migrated to the maintenance releases.

The above commands will install Perl to /usr/local (or some other platform-specific directory -- see the appropriate file in hints/.) If that's not okay with you, use

        rm -f config.sh Policy.sh
        sh Configure
        make test
        make install

For information on non-Unix systems, see the section on "Porting information" below.

If "make install" just says "`install' is up to date" or something similar, you may be on a case-insensitive filesystems such as Mac's HFS+, and you should say "make install-all". (This confusion is brought to you by the Perl distribution having a file called INSTALL.)

If you have problems, corrections, or questions, please see "Reporting Problems" below.

For information on what's new in this release, see the pod/perldelta.pod file. For more detailed information about specific changes, see the Changes file.


This document is written in pod format as an easy way to indicate its structure. The pod format is described in pod/perlpod.pod, but you can read it as is with any pager or editor. Headings and items are marked by lines beginning with '='. The other mark-up used is

    B<text>     embolden text, used for switches, programs or commands
    C<code>     literal code
    L<name>     A link (cross reference) to name

Although most of the defaults are probably fine for most users, you should probably at least skim through this entire document before proceeding.

If you're building Perl on a non-Unix system, you should also read the README file specific to your operating system, since this may provide additional or different instructions for building Perl. There are also README files for several flavors of Unix systems, such as Solaris, HP-UX, and AIX; if you have one of those systems, you should also read the README file specific to that system.

If there is a hint file for your system (in the hints/ directory) you should also read that hint file for specific information for your system. (Unixware users should use the svr4.sh hint file.) Additional information is in the Porting/ directory.

WARNING: This version requires an extra step to build old extensions.

5.005_53 and later releases do not export unadorned global symbols anymore. This means you may need to build rather old extensions that have not been updated for the current naming convention with:

        perl Makefile.PL POLLUTE=1

Alternatively, you can enable CPP symbol pollution wholesale by building perl itself with:

        sh Configure -Accflags=-DPERL_POLLUTE

pod/perl56delta.pod contains more details about this.

WARNING: This version is not binary compatible with releases of Perl prior to 5.8.0.

If you have built extensions (i.e. modules that include C code) using an earlier version of Perl, you will need to rebuild and reinstall those extensions.

Pure perl modules without XS or C code should continue to work fine without reinstallation. See the discussions below on "Coexistence with earlier versions of perl5" and "Upgrading from 5.005 or 5.6 to 5.8.0" for more details.

The standard extensions supplied with Perl will be handled automatically.

On a related issue, old modules may possibly be affected by the changes in the Perl language in the current release. Please see pod/perldelta.pod (and the earlier pod/perl5Xdelta.pod) for a description of what's changed. See your installed copy of the perllocal.pod file for a (possibly incomplete) list of locally installed modules. Also see CPAN::autobundle for one way to make a "bundle" of your currently installed modules.

WARNING: This version requires a compiler that supports ANSI C.

Most C compilers are now ANSI-compliant. However, a few current computers are delivered with an older C compiler expressly for rebuilding the system kernel, or for some other historical reason. Alternatively, you may have an old machine which was shipped before ANSI compliance became widespread. Such compilers are not suitable for building Perl.

If you find that your default C compiler is not ANSI-capable, but you know that an ANSI-capable compiler is installed on your system, you can tell Configure to use the correct compiler by means of the -Dcc= command-line option -- see "gcc".

If do not have an ANSI-capable compiler there are a couple of avenues open to you:

  • You may try obtaining GCC, available from GNU mirrors worldwide, listed at <URL:http://www.gnu.org/order/ftp.html>. If, rather than building gcc from source code, you locate a binary version configured for your platform, be sure that it is compiled for the version of the operating system that you are using.

  • You may purchase a commercial ANSI C compiler from your system supplier or elsewhere. (Or your organization may already have licensed such software -- ask your colleagues to find out how to access it.) If there is a README file for your system in the Perl distribution (for example, README.hpux), it may contain advice on suitable compilers.

Although Perl can be compiled using a C++ compiler, the Configure script does not work with some C++ compilers.

Space Requirements

The complete perl5 source tree takes up about 50 MB of disk space. After completing make, it takes up roughly 100 MB, though the actual total is likely to be quite system-dependent. The installation directories need something on the order of 45 MB, though again that value is system-dependent.

Start with a Fresh Distribution

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

        make distclean


        make realclean

The only difference between the two is that make distclean also removes your old config.sh and Policy.sh files.

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

        rm -f config.sh

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

Also, be careful to check your architecture name. For example, some Linux distributions use i386, while others may use i486. If you build it yourself, Configure uses the output of the arch command, which might be i586 or i686 instead. If you pick up a precompiled binary, or compile extensions on different systems, they might not all agree on the architecture name.

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

If your reason to reuse your old config.sh is to save your particular installation choices, then you can probably achieve the same effect by using the Policy.sh file. See the section on "Site-wide Policy settings" below. If you wish to start with a fresh distribution, you also need to remove any old Policy.sh files you may have with

        rm -f Policy.sh

Run Configure

Configure will figure out various things about your system. Some things Configure will figure out for itself, other things it will ask you about. To accept the default, just press RETURN. The default is almost always okay. It is normal for some things to be "NOT found", since Configure often searches for many different ways of performing the same function.

At any Configure prompt, you can type &-d and Configure will use the defaults from then on.

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

Altering config.sh variables for C compiler switches etc.

For most users, all of the Configure defaults are fine. Configure also has several convenient options which are described below. However, if Configure doesn't have an option to do what you want, you can change Configure variables after the platform hints have been run, by using Configure's -A switch. For example, here's how to add a couple of extra flags to C compiler invocations:

        sh Configure -Accflags="-DPERL_Y2KWARN -DPERL_POLLUTE_MALLOC"

For more help on Configure switches, run:

        sh Configure -h

Building Perl outside of the source directory

Sometimes it is desirable to build Perl in a directory different from where the sources are, for example if you want to keep your sources read-only, or if you want to share the sources between different binary architectures. You can do this (if your file system supports symbolic links) by

        mkdir /tmp/perl/build/directory
        cd /tmp/perl/build/directory
        sh /path/to/perl/source/Configure -Dmksymlinks ...

This will create in /tmp/perl/build/directory a tree of symbolic links pointing to files in /path/to/perl/source. The original files are left unaffected. After Configure has finished you can just say

        make all test

and Perl will be built and tested, all in /tmp/perl/build/directory.

Common Configure options

Configure supports a number of useful options. Run Configure -h to get a listing. See the Porting/Glossary file for a complete list of Configure variables you can set and their definitions.


To compile with gcc you should run

        sh Configure -Dcc=gcc

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

Installation prefix

By default, for most systems, perl will be installed in /usr/local/{bin, lib, man}. (See "Installation Directories" and "Coexistence with earlier versions of perl5" below for further details.)

You can specify a different 'prefix' for the default installation directory, when Configure prompts you or by using the Configure command line option -Dprefix='/some/directory', e.g.

        sh Configure -Dprefix=/opt/perl

If your prefix contains the string "perl", then the suggested directory structure is simplified. For example, if you use prefix=/opt/perl, then Configure will suggest /opt/perl/lib instead of /opt/perl/lib/perl5/. Again, see "Installation Directories" below for more details. Do not include a trailing slash, (i.e. /opt/perl/) or you may experience odd test failures.

NOTE: You must not specify an installation directory that is the same as or below your perl source directory. If you do, installperl will attempt infinite recursion.


It may seem obvious, but Perl is useful only when users can easily find it. It's often a good idea to have both /usr/bin/perl and /usr/local/bin/perl be symlinks to the actual binary. Be especially careful, however, not to overwrite a version of perl supplied by your vendor unless you are sure you know what you are doing.

By default, Configure will arrange for /usr/bin/perl to be linked to the current version of perl. You can turn off that behavior by running

        Configure -Uinstallusrbinperl

or by answering 'no' to the appropriate Configure prompt.

In any case, system administrators are strongly encouraged to put (symlinks to) perl and its accompanying utilities, such as perldoc, into a directory typically found along a user's PATH, or in another obvious and convenient place.

Overriding an old config.sh

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

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

        sh Configure -des

Note: for development releases (odd subreleases, like 5.9, as opposed to maintenance releases which have even subreleases, like 5.6 and 5.8) if you want to use Configure -d, you will also need to supply -Dusedevel to Configure, because the default answer to the question "do you really want to Configure a development version?" is "no". The -Dusedevel skips that sanity check.

For example for my Solaris system, I usually use

        sh Configure -Dprefix=/opt/perl -Doptimize='-xpentium -xO4' -des

GNU-style configure

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

        CC=gcc ./configure.gnu

The configure.gnu script emulates a few of the more common configure options. Try

        ./configure.gnu --help

for a listing.

(The file is called configure.gnu to avoid problems on systems that would not distinguish the files "Configure" and "configure".)

See Cross-compilation below for information on cross-compiling.

Installation Directories

The installation directories can all be changed by answering the appropriate questions in Configure. For convenience, all the installation questions are near the beginning of Configure. Do not include trailing slashes on directory names.

I highly recommend running Configure interactively to be sure it puts everything where you want it. At any point during the Configure process, you can answer a question with &-d and Configure will use the defaults from then on. Alternatively, you can

        grep '^install' config.sh

after Configure has run to verify the installation paths.

The defaults are intended to be reasonable and sensible for most people building from sources. Those who build and distribute binary distributions or who export perl to a range of systems will probably need to alter them. If you are content to just accept the defaults, you can safely skip the next section.

The directories set up by Configure fall into three broad categories.

Directories for the perl distribution

By default, Configure will use the following directories for 5.8.0. $version is the full perl version number, including subversion, e.g. 5.8.0 or 5.8.1, and $archname is a string like sun4-sunos, determined by Configure. The full definitions of all Configure variables are in the file Porting/Glossary.

    Configure variable  Default value
    $prefix             /usr/local
    $bin                $prefix/bin
    $scriptdir          $prefix/bin
    $privlib            $prefix/lib/perl5/$version
    $archlib            $prefix/lib/perl5/$version/$archname
    $man1dir            $prefix/man/man1
    $man3dir            $prefix/man/man3
    $html1dir           (none)
    $html3dir           (none)

Actually, Configure recognizes the SVR3-style /usr/local/man/l_man/man1 directories, if present, and uses those instead. Also, if $prefix contains the string "perl", the library directories are simplified as described below. For simplicity, only the common style is shown here.

Directories for site-specific add-on files

After perl is installed, you may later wish to add modules (e.g. from CPAN) or scripts. Configure will set up the following directories to be used for installing those add-on modules and scripts.

    Configure variable  Default value
    $siteprefix         $prefix
    $sitebin            $siteprefix/bin
    $sitescript         $siteprefix/bin
    $sitelib            $siteprefix/lib/perl5/site_perl/$version
    $sitearch           $siteprefix/lib/perl5/site_perl/$version/$archname
    $siteman1           $siteprefix/man/man1
    $siteman3           $siteprefix/man/man3
    $sitehtml1          (none)
    $sitehtml3          (none)

By default, ExtUtils::MakeMaker will install architecture-independent modules into $sitelib and architecture-dependent modules into $sitearch.

Directories for vendor-supplied add-on files

Lastly, if you are building a binary distribution of perl for distribution, Configure can optionally set up the following directories for you to use to distribute add-on modules.

    Configure variable  Default value
    $vendorprefix       (none)
    (The next ones are set only if vendorprefix is set.)
    $vendorbin          $vendorprefix/bin
    $vendorscript       $vendorprefix/bin
    $vendorlib          $vendorprefix/lib/perl5/vendor_perl/$version
    $vendorarch         $vendorprefix/lib/perl5/vendor_perl/$version/$archname
    $vendorman1         $vendorprefix/man/man1
    $vendorman3         $vendorprefix/man/man3
    $vendorhtml1        (none)
    $vendorhtml3        (none)

These are normally empty, but may be set as needed. For example, a vendor might choose the following settings:

        $prefix         /usr
        $siteprefix     /usr/local
        $vendorprefix   /usr

This would have the effect of setting the following:

        $bin            /usr/bin
        $scriptdir      /usr/bin
        $privlib        /usr/lib/perl5/$version
        $archlib        /usr/lib/perl5/$version/$archname
        $man1dir        /usr/man/man1
        $man3dir        /usr/man/man3

        $sitebin        /usr/local/bin
        $sitescript     /usr/local/bin
        $sitelib        /usr/local/lib/perl5/site_perl/$version
        $sitearch       /usr/local/lib/perl5/site_perl/$version/$archname
        $siteman1       /usr/local/man/man1
        $siteman3       /usr/local/man/man3

        $vendorbin      /usr/bin
        $vendorscript   /usr/bin
        $vendorlib      /usr/lib/perl5/vendor_perl/$version
        $vendorarch     /usr/lib/perl5/vendor_perl/$version/$archname
        $vendorman1     /usr/man/man1
        $vendorman3     /usr/man/man3

Note how in this example, the vendor-supplied directories are in the /usr hierarchy, while the directories reserved for the end-user are in the /usr/local hierarchy.

The entire installed library hierarchy is installed in locations with version numbers, keeping the installations of different versions distinct. However, later installations of Perl can still be configured to search the installed libraries corresponding to compatible earlier versions. See "Coexistence with earlier versions of perl5" below for more details on how Perl can be made to search older version directories.

Of course you may use these directories however you see fit. For example, you may wish to use $siteprefix for site-specific files that are stored locally on your own disk and use $vendorprefix for site-specific files that are stored elsewhere on your organization's network. One way to do that would be something like

        sh Configure -Dsiteprefix=/usr/local -Dvendorprefix=/usr/share/perl

As a final catch-all, Configure also offers an $otherlibdirs variable. This variable contains a colon-separated list of additional directories to add to @INC. By default, it will be empty. Perl will search these directories (including architecture and version-specific subdirectories) for add-on modules and extensions.

For example, if you have a bundle of perl libraries from a previous installation, perhaps in a strange place:

        Configure -Dotherlibdirs=/usr/lib/perl5/site_perl/5.6.1

There is one other way of adding paths to @INC at perl build time, and that is by setting the APPLLIB_EXP C pre-processor token to a colon- separated list of directories, like this

       sh Configure -Accflags='-DAPPLLIB_EXP=\"/usr/libperl\"'

The directories defined by APPLLIB_EXP get added to @INC first, ahead of any others, and so provide a way to override the standard perl modules should you, for example, want to distribute fixes without touching the perl distribution proper. And, like otherlib dirs, version and architecture specific subdirectories are also searched, if present, at run time. Of course, you can still search other @INC directories ahead of those in APPLLIB_EXP by using any of the standard run-time methods: $PERLLIB, $PERL5LIB, -I, use lib, etc.

Man Pages

In versions 5.005_57 and earlier, the default was to store module man pages in a version-specific directory, such as /usr/local/lib/perl5/$version/man/man3. The default for 5.005_58 and after is /usr/local/man/man3 so that most users can find the man pages without resetting MANPATH.

You can continue to use the old default from the command line with

        sh Configure -Dman3dir=/usr/local/lib/perl5/5.8.0/man/man3

Some users also prefer to use a .3pm suffix. You can do that with

        sh Configure -Dman3ext=3pm

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

HTML pages

Currently, the standard perl installation does not do anything with HTML documentation, but that may change in the future. Further, some add-on modules may wish to install HTML documents. The html Configure variables listed above are provided if you wish to specify where such documents should be placed. The default is "none", but will likely eventually change to something useful based on user feedback.

Some users prefer to append a "/share" to $privlib and $sitelib to emphasize that those directories can be shared among different architectures.

Note that these are just the defaults. You can actually structure the directories any way you like. They don't even have to be on the same filesystem.

Further details about the installation directories, maintenance and development subversions, and about supporting multiple versions are discussed in "Coexistence with earlier versions of perl5" below.

If you specify a prefix that contains the string "perl", then the library directory structure is slightly simplified. Instead of suggesting $prefix/lib/perl5/, Configure will suggest $prefix/lib.

Thus, for example, if you Configure with -Dprefix=/opt/perl, then the default library directories for 5.8.0 are

    Configure variable  Default value
        $privlib        /opt/perl/lib/5.8.0
        $archlib        /opt/perl/lib/5.8.0/$archname
        $sitelib        /opt/perl/lib/site_perl/5.8.0
        $sitearch       /opt/perl/lib/site_perl/5.8.0/$archname

Changing the installation directory

Configure distinguishes between the directory in which perl (and its associated files) should be installed and the directory in which it will eventually reside. For most sites, these two are the same; for sites that use AFS, this distinction is handled automatically. However, sites that use software such as depot to manage software packages, or users building binary packages for distribution may also wish to install perl into a different directory and use that management software to move perl to its final destination. This section describes how to do that.

Suppose you want to install perl under the /tmp/perl5 directory. You could edit config.sh and change all the install* variables to point to /tmp/perl5 instead of /usr/local, or you could simply use the following command line:

        sh Configure -Dinstallprefix=/tmp/perl5

(replace /tmp/perl5 by a directory of your choice).

Beware, though, that if you go to try to install new add-on modules, they too will get installed in under '/tmp/perl5' if you follow this example. The next section shows one way of dealing with that problem.

Creating an installable tar archive

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

    # Set up to install perl into a different directory,
    # e.g. /tmp/perl5 (see previous part).
    sh Configure -Dinstallprefix=/tmp/perl5 -Dprefix=/opt/perl -des
    make test
    make install   # This will install everything into /tmp/perl5.
    cd /tmp/perl5
    # Edit $archlib/Config.pm and $archlib/.packlist to change all the
    # install* variables back to reflect where everything will
    # really be installed.  (That is, change /tmp/perl5 to /opt/perl
    # everywhere in those files.)
    # Check the scripts in $scriptdir to make sure they have the correct
    # #!/wherever/perl line.
    tar cvf ../perl5-archive.tar .
    # Then, on each machine where you want to install perl,
    cd /opt/perl # Or wherever you specified as $prefix
    tar xvf perl5-archive.tar

Site-wide Policy settings

After Configure runs, it stores a number of common site-wide "policy" answers (such as installation directories and the local perl contact person) in the Policy.sh file. If you want to build perl on another system using the same policy defaults, simply copy the Policy.sh file to the new system and Configure will use it along with the appropriate hint file for your system.

Alternatively, if you wish to change some or all of those policy answers, you should

        rm -f Policy.sh

to ensure that Configure doesn't re-use them.

Further information is in the Policy_sh.SH file itself.

If the generated Policy.sh file is unsuitable, you may freely edit it to contain any valid shell commands. It will be run just after the platform-specific hints files.

Configure-time Options

There are several different ways to Configure and build perl for your system. For most users, the defaults are sensible and will work. Some users, however, may wish to further customize perl. Here are some of the main things you can change.


On some platforms, perl can be compiled with support for threads. To enable this, run

        sh Configure -Dusethreads

Currently, you need to specify -Dusethreads on the Configure command line so that the hint files can make appropriate adjustments.

The default is to compile without thread support.

Perl has two different internal threads implementations. The current model (available internally since 5.6, and as a user-level module since 5.8) is called interpreter-based implementation (ithreads), with one interpreter per thread, and explicit sharing of data.

The 5.005 version (5005threads) is considered obsolete, buggy, and unmaintained.

By default, Configure selects ithreads if -Dusethreads is specified.

(You need to also use the PerlIO layer, explained later, if you decide to use ithreads, to guarantee the good interworking of threads and I/O.)

However, if you wish, you can select the unsupported old 5005threads behavior

        sh Configure -Dusethreads -Duse5005threads

If you decide to use ithreads, the 'threads' module allows their use, and the 'Thread' module offers an interface to both 5005threads and ithreads (whichever has been configured).

Large file support.

Since Perl 5.6.0, Perl has supported large files (files larger than 2 gigabytes), and in many common platforms like Linux or Solaris this support is on by default.

This is both good and bad. It is good in that you can use large files, seek(), stat(), and -s them. It is bad in that if you are interfacing Perl using some extension, the components you are connecting to must also be large file aware: if Perl thinks files can be large but the other parts of the software puzzle do not understand the concept, bad things will happen. One popular extension suffering from this ailment is the Apache extension mod_perl.

There's also one known limitation with the current large files implementation: unless you also have 64-bit integers (see the next section), you cannot use the printf/sprintf non-decimal integer formats like %x to print filesizes. You can use %d, though.

64 bit support.

If your platform does not have 64 bits natively, but can simulate them with compiler flags and/or long long or int64_t, you can build a perl that uses 64 bits.

There are actually two modes of 64-bitness: the first one is achieved using Configure -Duse64bitint and the second one using Configure -Duse64bitall. The difference is that the first one is minimal and the second one maximal. The first works in more places than the second.

The use64bitint does only as much as is required to get 64-bit integers into Perl (this may mean, for example, using "long longs") while your memory may still be limited to 2 gigabytes (because your pointers could still be 32-bit). Note that the name 64bitint does not imply that your C compiler will be using 64-bit ints (it might, but it doesn't have to): the use64bitint means that you will be able to have 64 bits wide scalar values.

The use64bitall goes all the way by attempting to switch also integers (if it can), longs (and pointers) to being 64-bit. This may create an even more binary incompatible Perl than -Duse64bitint: the resulting executable may not run at all in a 32-bit box, or you may have to reboot/reconfigure/rebuild your operating system to be 64-bit aware.

Natively 64-bit systems like Alpha and Cray need neither -Duse64bitint nor -Duse64bitall.

    NOTE: 64-bit support is still experimental on most platforms.
    Existing support only covers the LP64 data model.  In particular, the
    LLP64 data model is not yet supported.  64-bit libraries and system
    APIs on many platforms have not stabilized--your mileage may vary.

Long doubles

In some systems you may be able to use long doubles to enhance the range and precision of your double precision floating point numbers (that is, Perl's numbers). Use Configure -Duselongdouble to enable this support (if it is available).

"more bits"

You can "Configure -Dusemorebits" to turn on both the 64-bit support and the long double support.

Selecting File IO mechanisms

Executive summary: in Perl 5.8, you should use the default "PerlIO" as the IO mechanism unless you have a good reason not to.

In more detail: previous versions of perl used the standard IO mechanisms as defined in stdio.h. Versions 5.003_02 and later of perl introduced alternate IO mechanisms via a "PerlIO" abstraction, but up until and including Perl 5.6, the stdio mechanism was still the default and the only supported mechanism.

Starting from Perl 5.8, the default mechanism is to use the PerlIO abstraction, because it allows better control of I/O mechanisms, instead of having to work with (often, work around) vendors' I/O implementations.

This PerlIO abstraction can be (but again, unless you know what you are doing, should not be) disabled either on the Configure command line with

        sh Configure -Uuseperlio

or interactively at the appropriate Configure prompt.

With the PerlIO abstraction layer, there is another possibility for the underlying IO calls, AT&T's "sfio". This has superior performance to stdio.h in many cases, and is extensible by the use of "discipline" modules ("Native" PerlIO has them too). Sfio currently only builds on a subset of the UNIX platforms perl supports. Because the data structures are completely different from stdio, perl extension modules or external libraries may not work. This configuration exists to allow these issues to be worked on.

This option requires the 'sfio' package to have been built and installed. The latest sfio is available from http://www.research.att.com/sw/tools/sfio/

You select this option by

        sh Configure -Duseperlio -Dusesfio

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

Note: On some systems, sfio's iffe configuration script fails to detect that you have an atexit function (or equivalent). Apparently, this is a problem at least for some versions of Linux and SunOS 4. Configure should detect this problem and warn you about problems with _exit vs. exit. If you have this problem, the fix is to go back to your sfio sources and correct iffe's guess about atexit.


Perl can be configured to be 'socksified', that is, to use the SOCKS TCP/IP proxy protocol library. SOCKS is used to give applications access to transport layer network proxies. Perl supports only SOCKS Version 5. You can find more about SOCKS from http://www.socks.nec.com/

Dynamic Loading

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

Building a shared Perl library

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

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

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

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

The default name for the shared library is typically something like libperl.so.3.2 (for Perl 5.003_02) or libperl.so.302 or simply libperl.so. Configure tries to guess a sensible naming convention based on your C library name. Since the library gets installed in a version-specific architecture-dependent directory, the exact name isn't very important anyway, as long as your linker is happy.

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

You can elect to build a shared libperl by

        sh Configure -Duseshrplib

To build a shared libperl, the environment variable controlling shared library search (LD_LIBRARY_PATH in most systems, DYLD_LIBRARY_PATH for NeXTSTEP/OPENSTEP/Darwin, LIBRARY_PATH for BeOS, LD_LIBRARY_PATH/SHLIB_PATH for HP-UX, LIBPATH for AIX, PATH for Cygwin) must be set up to include the Perl build directory because that's where the shared libperl will be created. Configure arranges makefile to have the correct shared library search settings. You can find the name of the environment variable Perl thinks works in your your system by

        grep ldlibpthname config.sh

However, there are some special cases where manually setting the shared library path might be required. For example, if you want to run something like the following with the newly-built but not-yet-installed ./perl:

        cd t; ./perl misc/failing_test.t
        ./perl -Ilib ~/my_mission_critical_test

then you need to set up the shared library path explicitly. You can do this with


for Bourne-style shells, or

   setenv LD_LIBRARY_PATH `pwd`

for Csh-style shells. (This procedure may also be needed if for some unexpected reason Configure fails to set up makefile correctly.) (And again, it may be something other than LD_LIBRARY_PATH for you, see above.)

You can often recognize failures to build/use a shared libperl from error messages complaining about a missing libperl.so (or libperl.sl in HP-UX), for example: 18126:./miniperl: /sbin/loader: Fatal Error: cannot map libperl.so

There is also an potential problem with the shared perl library if you want to have more than one "flavor" of the same version of perl (e.g. with and without -DDEBUGGING). For example, suppose you build and install a standard Perl 5.8.0 with a shared library. Then, suppose you try to build Perl 5.8.0 with -DDEBUGGING enabled, but everything else the same, including all the installation directories. How can you ensure that your newly built perl will link with your newly built libperl.so.8 rather with the installed libperl.so.8? The answer is that you might not be able to. The installation directory is encoded in the perl binary with the LD_RUN_PATH environment variable (or equivalent ld command-line option). On Solaris, you can override that with LD_LIBRARY_PATH; on Linux you can't. On Digital Unix, you can override LD_LIBRARY_PATH by setting the _RLD_ROOT environment variable to point to the perl build directory.

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

Malloc Issues

Perl relies heavily on malloc(3) to grow data structures as needed, so perl's performance can be noticeably affected by the performance of the malloc function on your system. The perl source is shipped with a version of malloc that has been optimized for the typical requests from perl, so there's a chance that it may be both faster and use less memory than your system malloc.

However, if your system already has an excellent malloc, or if you are experiencing difficulties with extensions that use third-party libraries that call malloc, then you should probably use your system's malloc. (Or, you might wish to explore the malloc flags discussed below.)

Using the system malloc

To build without perl's malloc, you can use the Configure command

        sh Configure -Uusemymalloc

or you can answer 'n' at the appropriate interactive Configure prompt.


NOTE: This flag is enabled automatically on some platforms if you just run Configure to accept all the defaults on those platforms.

Perl's malloc family of functions are normally called Perl_malloc(), Perl_realloc(), Perl_calloc() and Perl_mfree(). These names do not clash with the system versions of these functions.

If this flag is enabled, however, Perl's malloc family of functions will have the same names as the system versions. This may be required sometimes if you have libraries that like to free() data that may have been allocated by Perl_malloc() and vice versa.

Note that enabling this option may sometimes lead to duplicate symbols from the linker for malloc et al. In such cases, the system probably does not allow its malloc functions to be fully replaced with custom versions.

Building a debugging perl

You can run perl scripts under the perl debugger at any time with perl -d your_script. If, however, you want to debug perl itself, you probably want to do

        sh Configure -Doptimize='-g'

This will do two independent things: First, it will force compilation to use cc -g so that you can use your system's debugger on the executable. (Note: Your system may actually require something like cc -g2. Check your man pages for cc(1) and also any hint file for your system.) Second, it will add -DDEBUGGING to your ccflags variable in config.sh so that you can use perl -D to access perl's internal state. (Note: Configure will only add -DDEBUGGING by default if you are not reusing your old config.sh. If you want to reuse your old config.sh, then you can just edit it and change the optimize and ccflags variables by hand and then propagate your changes as shown in "Propagating your changes to config.sh" below.)

You can actually specify -g and -DDEBUGGING independently, but usually it's convenient to have both.

If you are using a shared libperl, see the warnings about multiple versions of perl under "Building a shared libperl.so Perl library".


Perl ships with a number of standard extensions. These are contained in the ext/ subdirectory.

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

If you unpack any additional extensions in the ext/ directory before running Configure, then Configure will offer to build those additional extensions as well. Most users probably shouldn't have to do this -- it is usually easier to build additional extensions later after perl has been installed. However, if you wish to have those additional extensions statically linked into the perl binary, then this offers a convenient way to do that in one step. (It is not necessary, however; you can build and install extensions just fine even if you don't have dynamic loading. See lib/ExtUtils/MakeMaker.pm for more details.)

You can learn more about each of the supplied extensions by consulting the documentation in the individual .pm modules, located under the ext/ subdirectory.

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

In summary, here are the Configure command-line variables you can set to turn off various extensions. All others are included by default.

    DB_File             i_db
    DynaLoader          (Must always be included as a static extension)
    GDBM_File           i_gdbm
    NDBM_File           i_ndbm
    ODBM_File           i_dbm
    POSIX               useposix
    Opcode              useopcode
    Socket              d_socket
    Threads             use5005threads

Thus to skip the NDBM_File extension, you can use

        sh Configure -Ui_ndbm

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

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

Note: The DB_File module will only work with version 1.x of Berkeley DB or newer releases of version 2. Configure will automatically detect this for you and refuse to try to build DB_File with earlier releases of version 2.

If you re-use your old config.sh but change your system (e.g. by adding libgdbm) Configure will still offer your old choices of extensions for the default answer, but it will also point out the discrepancy to you.

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

Including locally-installed libraries

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

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


gdbm in /usr/local

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

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

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

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

Again, this should all happen automatically. This should also work if you have gdbm installed in any of (/usr/local, /opt/local, /usr/gnu, /opt/gnu, /usr/GNU, or /opt/GNU).

gdbm in /usr/you

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

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

        sh Configure -de \
                -Dlocincpth="/usr/you/include" \

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

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

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

Building DB, NDBM, and ODBM interfaces with Berkeley DB 3

Perl interface for DB3 is part of Berkeley DB, but if you want to compile standard Perl DB/ODBM/NDBM interfaces, you must follow following instructions.

Berkeley DB3 from Sleepycat Software is by default installed without DB1 compatibility code (needed for DB_File interface) and without links to compatibility files. So if you want to use packages written for DB/ODBM/NDBM interfaces, you need to configure DB3 with --enable-compat185 (and optionally with --enable-dump185) and create additional references (suppose you are installing DB3 with --prefix=/usr):

    ln -s libdb-3.so /usr/lib/libdbm.so
    ln -s libdb-3.so /usr/lib/libndbm.so
    echo '#define DB_DBM_HSEARCH 1' >dbm.h 
    echo '#include <db.h>' >>dbm.h
    install -m 0644 dbm.h /usr/include/dbm.h 
    install -m 0644 dbm.h /usr/include/ndbm.h

Optionally, if you have compiled with --enable-compat185 (not needed for ODBM/NDBM):

    ln -s libdb-3.so /usr/lib/libdb1.so
    ln -s libdb-3.so /usr/lib/libdb.so

ODBM emulation seems not to be perfect, but is quite usable, using DB 3.1.17:

    lib/odbm.............FAILED at test 9
        Failed 1/64 tests, 98.44% okay

What if it doesn't work?

If you run into problems, try some of the following ideas. If none of them help, then see "Reporting Problems" below.

Running Configure Interactively

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

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

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

Hint files

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

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

*** WHOA THERE!!! ***

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

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

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

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

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

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

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

Changing Compilers

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

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

Propagating your changes to config.sh

If you make any changes to config.sh, you should propagate them to all the .SH files by running

        sh Configure -S

You will then have to rebuild by running

        make depend
config.over and config.arch

You can also supply a shell script config.over to over-ride Configure's guesses. It will get loaded up at the very end, just before config.sh is created. You have to be careful with this, however, as Configure does no checking that your changes make sense. This file is usually good for site-specific customizations.

There is also another file that, if it exists, is loaded before the config.over, called config.arch. This file is intended to be per architecture, not per site, and usually it's the architecture-specific hints file that creates the config.arch.


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

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


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

To explore various ways of changing ccflags from within a hint file, see the file hints/README.hints.

To change the C flags for all the files, edit config.sh and change either $ccflags or $optimize, and then re-run

        sh Configure -S
        make depend
No sh

If you don't have sh, you'll have to copy the sample file Porting/config.sh to config.sh and edit your config.sh to reflect your system's peculiarities. See Porting/pumpkin.pod for more information. You'll probably also have to extensively modify the extension building mechanism.

Digital UNIX/Tru64 UNIX and BIN_SH

In Digital UNIX/Tru64 UNIX, Configure might abort with

Build a threading Perl? [n] Configure[2437]: Syntax error at line 1 : `config.sh' is not expected.

This indicates that Configure is being run with a broken Korn shell (even though you think you are using a Bourne shell by using "sh Configure" or "./Configure"). The Korn shell bug has been reported to Compaq as of February 1999 but in the meanwhile, the reason ksh is being used is that you have the environment variable BIN_SH set to 'xpg4'. This causes /bin/sh to delegate its duties to /bin/posix/sh (a ksh). Unset the environment variable and rerun Configure.

HP-UX 11, pthreads, and libgdbm

If you are running Configure with -Dusethreads in HP-UX 11, be warned that POSIX threads and libgdbm (the GNU dbm library) compiled before HP-UX 11 do not mix. This will cause a basic test run by Configure to fail

Pthread internal error: message: __libc_reinit() failed, file: ../pthreads/pthread.c, line: 1096 Return Pointer is 0xc082bf33 sh: 5345 Quit(coredump)

and Configure will give up. The cure is to recompile and install libgdbm under HP-UX 11.

Porting information

Specific information for the OS/2, Plan 9, VMS and Win32 ports is in the corresponding README files and subdirectories. Additional information, including a glossary of all those config.sh variables, is in the Porting subdirectory. Especially Porting/Glossary should come in handy.

Ports for other systems may also be available. You should check out http://www.cpan.org/ports for current information on ports to various other operating systems.

If you plan to port Perl to a new architecture study carefully the section titled "Philosophical Issues in Patching and Porting Perl" in the file Porting/pumpkin.pod and the file Porting/patching.pod. Study also how other non-UNIX ports have solved problems.

Adding extra modules to the build

You can specify extra modules or module bundles to be fetched from the CPAN and installed as part of the Perl build. Either use the -Dextras=... command line parameter to Configure, for example like this:

        Configure -Dextras="Compress::Zlib Bundle::LWP DBI"

or answer first 'y' to the question 'Install any extra modules?' and then answer "Compress::Zlib Bundle::LWP DBI" to the 'Extras?' question. The module or the bundle names are as for the CPAN module 'install' command.

Notice that because the CPAN module will be used to fetch the extra modules, you will need access to the CPAN, either via the Internet, or via a local copy such as a CD-ROM or a local CPAN mirror. If you do not, using the extra modules option will die horribly.

Also notice that you yourself are responsible for satisfying any extra dependencies such as external headers or libraries BEFORE trying the build. For example: you will need to have the zlib.h header and the libz library installed for the Compress::Zlib, or the Foo database specific headers and libraries installed for the DBD::Foo module. The Configure process or the Perl build process will not help you with these.


suidperl is an optional component, which is built or installed by default. From perlfaq1:

        On some systems, setuid and setgid scripts (scripts written
        in the C shell, Bourne shell, or Perl, for example, with the
        set user or group ID permissions enabled) are insecure due to
        a race condition in the kernel. For those systems, Perl versions
        5 and 4 attempt to work around this vulnerability with an optional
        component, a special program named suidperl, also known as sperl.
        This program attempts to emulate the set-user-ID and set-group-ID
        features of the kernel.

Because of the buggy history of suidperl, and the difficulty of properly security auditing as large and complex piece of software as Perl, we cannot recommend using suidperl and the feature should be considered deprecated. Instead use for example 'sudo': http://www.courtesan.com/sudo/

make depend

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

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


This will attempt to make perl in the current directory.

What if it doesn't work?

If you can't compile successfully, try some of the following ideas. If none of them help, and careful reading of the error message and the relevant manual pages on your system doesn't help, then see "Reporting Problems" below.


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


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

        make minitest

to test your version of miniperl.


If you have any locale-related environment variables set, try unsetting them. I have some reports that some versions of IRIX hang while running ./miniperl configpm with locales other than the C locale. See the discussion under "make test" below about locales and the whole "Locale problems" section in the file pod/perllocale.pod. The latter is especially useful if you see something like this

        perl: warning: Setting locale failed.
        perl: warning: Please check that your locale settings:
                LC_ALL = "En_US",
                LANG = (unset)
            are supported and installed on your system.
        perl: warning: Falling back to the standard locale ("C").

at Perl startup.


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


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

    util.c: In function `Perl_form':
    util.c:1107: number of arguments doesn't match prototype
    proto.h:125: prototype declaration

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


If you run into dynamic loading problems, check your setting of the LD_LIBRARY_PATH environment variable. If you're creating a static Perl library (libperl.a rather than libperl.so) it should build fine with LD_LIBRARY_PATH unset, though that may depend on details of your local set-up.

nm extraction

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

        sh Configure -Uusenm

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

umask not found

If the build processes encounters errors relating to umask(), the problem is probably that Configure couldn't find your umask() system call. Check your config.sh. You should have d_umask='define'. If you don't, this is probably the "nm extraction" problem discussed above. Also, try reading the hints file for your system for further information.


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


If Configure guessed wrong, it is likely that Configure guessed wrong on a number of other common functions too. This is probably the "nm extraction" problem discussed above.


If you run into problems relating to do_aspawn or do_spawn, the problem is probably that Configure failed to detect your system's fork() function. Follow the procedure in the previous item on "nm extraction".

__inet_* errors

If you receive unresolved symbol errors during Perl build and/or test referring to __inet_* symbols, check to see whether BIND 8.1 is installed. It installs a /usr/local/include/arpa/inet.h that refers to these symbols. Versions of BIND later than 8.1 do not install inet.h in that location and avoid the errors. You should probably update to a newer version of BIND. If you can't, you can either link with the updated resolver library provided with BIND 8.1 or rename /usr/local/bin/arpa/inet.h during the Perl build and test process to avoid the problem.

#error "No DATAMODEL_NATIVE specified"

This is a common error when trying to build perl on Solaris 2.6 with a gcc installation from Solaris 2.5 or 2.5.1. The Solaris header files changed, so you need to update your gcc installation. You can either rerun the fixincludes script from gcc or take the opportunity to update your gcc installation.


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



        optimize=' '

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

Missing functions

If you have missing routines, you probably need to add some library or other, or you need to undefine some feature that Configure thought was there but is defective or incomplete. Look through config.h for likely suspects. If Configure guessed wrong on a number of functions, you might have the "nm extraction" problem discussed above.


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

Missing dbmclose

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

Note (probably harmless): No library found for -lsomething

If you see such a message during the building of an extension, but the extension passes its tests anyway (see "make test" below), then don't worry about the warning message. The extension Makefile.PL goes looking for various libraries needed on various systems; few systems will need all the possible libraries listed. For example, a system may have -lcposix or -lposix, but it's unlikely to have both, so most users will see warnings for the one they don't have. The phrase 'probably harmless' is intended to reassure you that nothing unusual is happening, and the build process is continuing.

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

    Note (probably harmless): No library found for -lgdbm

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

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

sh: ar: not found

This is a message from your shell telling you that the command 'ar' was not found. You need to check your PATH environment variable to make sure that it includes the directory with the 'ar' command. This is a common problem on Solaris, where 'ar' is in the /usr/ccs/bin directory.

db-recno failure on tests 51, 53 and 55

Old versions of the DB library (including the DB library which comes with FreeBSD 2.1) had broken handling of recno databases with modified bval settings. Upgrade your DB library or OS.

Bad arg length for semctl, is XX, should be ZZZ

If you get this error message from the lib/ipc_sysv test, your System V IPC may be broken. The XX typically is 20, and that is what ZZZ also should be. Consider upgrading your OS, or reconfiguring your OS to include the System V semaphores.

lib/ipc_sysv........semget: No space left on device

Either your account or the whole system has run out of semaphores. Or both. Either list the semaphores with "ipcs" and remove the unneeded ones (which ones these are depends on your system and applications) with "ipcrm -s SEMAPHORE_ID_HERE" or configure more semaphores to your system.

GNU binutils

If you mix GNU binutils (nm, ld, ar) with equivalent vendor-supplied tools you may be in for some trouble. For example creating archives with an old GNU 'ar' and then using a new current vendor-supplied 'ld' may lead into linking problems. Either recompile your GNU binutils under your current operating system release, or modify your PATH not to include the GNU utils before running Configure, or specify the vendor-supplied utilities explicitly to Configure, for example by Configure -Dar=/bin/ar.


The Configure program has not been able to find all the files which make up the complete Perl distribution. You may have a damaged source archive file (in which case you may also have seen messages such as gzip: stdin: unexpected end of file and tar: Unexpected EOF on archive file), or you may have obtained a structurally-sound but incomplete archive. In either case, try downloading again from the official site named at the start of this document. If you do find that any site is carrying a corrupted or incomplete source code archive, please report it to the site's maintainer.

invalid token: ##

You are using a non-ANSI-compliant C compiler. See "WARNING: This version requires a compiler that supports ANSI C".


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

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

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

UTS may need one or more of -K or -g, and undef LSTAT.

FreeBSD can fail the lib/ipc_sysv.t test if SysV IPC has not been configured in the kernel. Perl tries to detect this, though, and you will get a message telling what to do.

HP-UX 11 Y2K patch "Y2K-1100 B.11.00.B0125 HP-UX Core OS Year 2000 Patch Bundle" has been reported to break the io/fs test #18 which tests whether utime() can change timestamps. The Y2K patch seems to break utime() so that over NFS the timestamps do not get changed (on local filesystems utime() still works).


Starting from Perl 5.8 Perl has the beginnings of cross-compilation support. What is known to work is running Configure in a cross-compilation environment and building the miniperl executable. What is known not to work is building the perl executable because that would require building extensions: Dynaloader statically and File::Glob dynamically, for extensions one needs MakeMaker and MakeMaker is not yet cross-compilation aware, and neither is the main Makefile.

Since the functionality is so lacking, it must be considered highly experimental. It is so experimental that it is not even mentioned during an interactive Configure session, a direct command line invocation (detailed shortly) is required to access the functionality.

    NOTE: Perl is routinely built using cross-compilation
    in the EPOC environment but the solutions from there
    can't directly be used elsewhere.

The one environment where cross-compilation has successfully been used as of this writing is the Compaq iPAQ running ARM Linux. The build host was Intel Linux, the networking setup was PPP + SSH. The exact setup details are beyond the scope of this document, see http://www.handhelds.org/ for more information.

To run Configure in cross-compilation mode the basic switch is -Dusecrosscompile.

   sh ./Configure -des -Dusecrosscompile -D...

This will make the cpp symbol USE_CROSS_COMPILE and the %Config symbol usecrosscompile available.

During the Configure and build, certain helper scripts will be created into the Cross/ subdirectory. The scripts are used to execute a cross-compiled executable, and to transfer files to and from the target host. The execution scripts are named run-* and the transfer scripts to-* and from-*. The part after the dash is the method to use for remote execution and transfer: by default the methods are ssh and scp, thus making the scripts run-ssh, to-scp, and from-scp.

To configure the scripts for a target host and a directory (in which the execution will happen and which is to and from where the transfer happens), supply Configure with

    -Dtargethost=so.me.ho.st -Dtargetdir=/tar/get/dir

The targethost is what e.g. ssh will use as the hostname, the targetdir must exist (the scripts won't create it), the targetdir defaults to /tmp. You can also specify a username to use for ssh/rsh logins


but in case you don't, "root" will be used.

Because this is a cross-compilation effort, you will also need to specify which target environment and which compilation environment to use. This includes the compiler, the header files, and the libraries. In the below we use the usual settings for the iPAQ cross-compilation environment:


If the name of the cc has the usual GNU C semantics for cross compilers, that is, CPU-OS-gcc, the names of the ar, nm, and ranlib will also be automatically chosen to be CPU-OS-ar and so on. (The ld requires more thought and will be chosen later by Configure as appropriate.) Also, in this case the incpth, libpth, and usrinc will be guessed by Configure (unless explicitly set to something else, in which case Configure's guesses with be appended).

In addition to the default execution/transfer methods you can also choose rsh for execution, and rcp or cp for transfer, for example:

    -Dtargetrun=rsh -Dtargetto=rcp -Dtargetfrom=cp

Putting it all together:

    sh ./Configure -des -Dusecrosscompile \
        -Dtargethost=so.me.ho.st \
        -Dtargetdir=/tar/get/dir \
        -Dtargetuser=root \
        -Dtargetarch=arm-linux \
        -Dcc=arm-linux-gcc \
        -Dusrinc=/skiff/local/arm-linux/include \
        -Dincpth=/skiff/local/arm-linux/include \
        -Dlibpth=/skiff/local/arm-linux/lib \

or if you are happy with the defaults

    sh ./Configure -des -Dusecrosscompile \
        -Dtargethost=so.me.ho.st \
        -Dcc=arm-linux-gcc \

make test

This will run the regression tests on the perl you just made. If 'make test' doesn't say "All tests successful" then something went wrong. See the file t/README in the t subdirectory.

Note that you can't run the tests in background if this disables opening of /dev/tty. You can use 'make test-notty' in that case but a few tty tests will be skipped.

What if make test doesn't work?

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

        ./perl op/groups.t

Another way to get more detailed information about failed tests and individual subtests is to cd to the t directory and run

        ./perl harness

(this assumes that most basic tests succeed, since harness uses complicated constructs). For extension and library tests you need a little bit more: you need to setup your environment variable PERL_CORE to a true value (like "1"), and you need to supply the right Perl library path:

        setenv PERL_CORE 1
        ./perl -I../lib ../ext/Socket/Socket.t
        ./perl -I../lib ../lib/less.t

(For csh-like shells on UNIX; adjust appropriately for other platforms.) You should also read the individual tests to see if there are any helpful comments that apply to your system. You may also need to setup your shared library path if you get errors like:

        /sbin/loader: Fatal Error: cannot map libperl.so

See "Building a shared Perl library" earlier in this document.


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

If you have any of the above environment variables set, please try

        setenv LC_ALL C

(for C shell) or

        LC_ALL=C;export LC_ALL

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

Timing problems

Several tests in the test suite check timing functions, such as sleep(), and see if they return in a reasonable amount of time. If your system is quite busy and doesn't respond quickly enough, these tests might fail. If possible, try running the tests again with the system under a lighter load. These timing-sensitive and load-sensitive tests include t/op/alarm.t, ext/Time/HiRes/HiRes.t, lib/Benchmark.t, lib/Memoize/t/expmod_t.t, and lib/Memoize/t/speed.t.

Out of memory

On some systems, particularly those with smaller amounts of RAM, some of the tests in t/op/pat.t may fail with an "Out of memory" message. For example, on my SparcStation IPC with 12 MB of RAM, in perl5.5.670, test 85 will fail if run under either t/TEST or t/harness.

Try stopping other jobs on the system and then running the test by itself:

        cd t; ./perl op/pat.t

to see if you have any better luck. If your perl still fails this test, it does not necessarily mean you have a broken perl. This test tries to exercise the regular expression subsystem quite thoroughly, and may well be far more demanding than your normal usage.

Test failures from lib/ftmp-security saying "system possibly insecure"

Firstly, test failures from the ftmp-security are not necessarily serious or indicative of a real security threat. That being said, they bear investigating.

The tests may fail for the following reasons. Note that each of the tests is run both in the building directory and the temporary directory, as returned by File::Spec->tmpdir().

(1) If the directory the tests are being run is owned by somebody else than the user running the tests, or root (uid 0). This failure can happen if the Perl source code distribution is unpacked in a way that the user ids in the distribution package are used as-is. Some tar programs do this.

(2) If the directory the tests are being run in is writable by group or by others (remember: with UNIX/POSIX semantics, write access to a directory means the right to add/remove files in that directory), and there is no sticky bit set in the directory. 'Sticky bit' is a feature used in some UNIXes to give extra protection to files: if the bit is on a directory, no one but the owner (or the root) can remove that file even if the permissions of the directory would allow file removal by others. This failure can happen if the permissions in the directory simply are a bit too liberal for the tests' liking. This may or may not be a real problem: it depends on the permissions policy used on this particular directory/project/system/site. This failure can also happen if the system either doesn't support the sticky bit (this is the case with many non-UNIX platforms: in principle File::Temp should know about these platforms and skip the tests), or if the system supports the sticky bit but for some reason or reasons it is not being used. This is for example the case with HP-UX: as of HP-UX release 11.00, the sticky bit is very much supported, but HP-UX doesn't use it on its /tmp directory as shipped. Also, as with the permissions, some local policy might dictate that the stickiness is not used.

(3) If the system supports the POSIX 'chown giveaway' feature and if any of the parent directories of the temporary file back to the root directory are 'unsafe', using the definitions given above in (1) and (2).

See the documentation for the File::Temp module for more information about the various security aspects.

make install

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

Installing perl under different names

If you want to install perl under a name other than "perl" (for example, when installing perl with special features enabled, such as debugging), indicate the alternate name on the "make install" line, such as:

    make install PERLNAME=myperl

You can separately change the base used for versioned names (like "perl5.005") by setting PERLNAME_VERBASE, like

    make install PERLNAME=perl5 PERLNAME_VERBASE=perl

This can be useful if you have to install perl as "perl5" (e.g. to avoid conflicts with an ancient version in /usr/bin supplied by your vendor). Without this the versioned binary would be called "perl55.005".

Installed files

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

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

make install will install the following:


            perl5.nnn   where nnn is the current release number.  This
                        will be a link to perl.
            sperl5.nnn  If you requested setuid emulation.
        a2p             awk-to-perl translator


        cppstdin        This is used by perl -P, if your cc -E can't
                        read from stdin.
        c2ph, pstruct   Scripts for handling C structures in header files.
        s2p             sed-to-perl translator
        find2perl       find-to-perl translator
        h2ph            Extract constants and simple macros from C headers
        h2xs            Converts C .h header files to Perl extensions.
        perlbug         Tool to report bugs in Perl.
        perldoc         Tool to read perl's pod documentation.
        pl2pm           Convert Perl 4 .pl files to Perl 5 .pm modules
        pod2html,       Converters from perl's pod documentation format
        pod2latex,      to other useful formats.
        splain          Describe Perl warnings and errors
        dprofpp         Perl code profile post-processor

    library files

                        in $privlib and $archlib specified to
                        Configure, usually under /usr/local/lib/perl5/.


        man pages       in $man1dir, usually /usr/local/man/man1.
        module man
        pages           in $man3dir, usually /usr/local/man/man3.
        pod/*.pod       in $privlib/pod/.

Installperl will also create the directories listed above in "Installation Directories".

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

Sometimes you only want to install the version-specific parts of the perl installation. For example, you may wish to install a newer version of perl alongside an already installed production version of perl without disabling installation of new modules for the production version. To only install the version-specific parts of the perl installation, run

        Configure -Dversiononly

or answer 'y' to the appropriate Configure prompt. Alternatively, you can just manually run

        ./perl installperl -v

and skip installman altogether. See also "Maintaining completely separate versions" for another approach.

Coexistence with earlier versions of perl5

Perl 5.8 is not binary compatible with earlier versions of Perl. In other words, you will have to recompile your XS modules.

In general, you can usually safely upgrade from one version of Perl (e.g. 5.004_04) to another similar version (e.g. 5.004_05) without re-compiling all of your add-on extensions. You can also safely leave the old version around in case the new version causes you problems for some reason. For example, if you want to be sure that your script continues to run with 5.004_04, simply replace the '#!/usr/local/bin/perl' line at the top of the script with the particular version you want to run, e.g. #!/usr/local/bin/perl5.00404.

Usually, most extensions will probably not need to be recompiled to use with a newer version of Perl (the Perl 5.6 to Perl 5.8 transition being an exception). Here is how it is supposed to work. (These examples assume you accept all the Configure defaults.)

Suppose you already have version 5.005_03 installed. The directories searched by 5.005_03 are


Beginning with 5.6.0 the version number in the site libraries are fully versioned. Now, suppose you install version 5.6.0. The directories searched by version 5.6.0 will be



Notice the last three entries -- Perl understands the default structure of the $sitelib directories and will look back in older, compatible directories. This way, modules installed under 5.005_03 will continue to be usable by 5.005_03 but will also accessible to 5.6.0. Further, suppose that you upgrade a module to one which requires features present only in 5.6.0. That new module will get installed into /usr/local/lib/perl5/site_perl/5.6.0 and will be available to 5.6.0, but will not interfere with the 5.005_03 version.

The last entry, /usr/local/lib/perl5/site_perl/, is there so that 5.6.0 and above will look for 5.004-era pure perl modules.

Lastly, suppose you now install 5.8.0, which is not binary compatible with 5.6.0. The directories searched by 5.8.0 (if you don't change the Configure defaults) will be:





Note that the earlier $archname entries are now gone, but pure perl modules from earlier versions will still be found.

Assuming the users in your site are still actively using perl 5.6.0 and 5.005 after you installed 5.8.0, you can continue to install add-on extensions using any of perl 5.8.0, 5.6.0, or 5.005. The installations of these different versions remain distinct, but remember that the newer versions of perl are automatically set up to search the compatible site libraries of the older ones. This means that installing a new XS extension with 5.005 will make it visible to both 5.005 and 5.6.0, but not to 5.8.0. Installing a pure perl module with 5.005 will make it visible to all three versions. Later, if you install the same extension using, say, perl 5.8.0, it will override the 5.005-installed version, but only for perl 5.8.0.

This way, you can choose to share compatible extensions, but also upgrade to a newer version of an extension that may be incompatible with earlier versions, without breaking the earlier versions' installations.

Maintaining completely separate versions

Many users prefer to keep all versions of perl in completely separate directories. This guarantees that an update to one version won't interfere with another version. (The defaults guarantee this for libraries after 5.6.0, but not for executables. TODO?) One convenient way to do this is by using a separate prefix for each version, such as

        sh Configure -Dprefix=/opt/perl5.004

and adding /opt/perl5.004/bin to the shell PATH variable. Such users may also wish to add a symbolic link /usr/local/bin/perl so that scripts can still start with #!/usr/local/bin/perl.

Others might share a common directory for maintenance sub-versions (e.g. 5.8 for all 5.8.x versions), but change directory with each major version.

If you are installing a development subversion, you probably ought to seriously consider using a separate directory, since development subversions may not have all the compatibility wrinkles ironed out yet.

Upgrading from 5.005 or 5.6 to 5.8.0

Perl 5.8.0 is binary incompatible with Perl 5.6.1, 5.6.0, 5.005, and any earlier Perl release. Perl modules having binary parts (meaning that a C compiler is used) will have to be recompiled to be used with 5.8.0. If you find you do need to rebuild an extension with 5.8.0, you may safely do so without disturbing the 5.005 or 5.6.0 installations. (See "Coexistence with earlier versions of perl5" above.)

See your installed copy of the perllocal.pod file for a (possibly incomplete) list of locally installed modules. Note that you want perllocal.pod, not perllocale.pod, for installed module information.

Coexistence with perl4

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

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

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

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

Some perl scripts need to be able to obtain information from the system header files. This command will convert the most commonly used header files in /usr/include into files that can be easily interpreted by perl. These files will be placed in the architecture-dependent library ($archlib) directory you specified to Configure.

Note: Due to differences in the C and perl languages, the conversion of the header files is not perfect. You will probably have to hand-edit some of the converted files to get them to parse correctly. For example, h2ph breaks spectacularly on type casting and certain structures.

installhtml --help

Some sites may wish to make perl documentation available in HTML format. The installhtml utility can be used to convert pod documentation into linked HTML files and install them.

Currently, the supplied ./installhtml script does not make use of the html Configure variables. This should be fixed in a future release.

The following command-line is an example of one used to convert perl documentation:

  ./installhtml                   \
      --podroot=.                 \
      --podpath=lib:ext:pod:vms   \
      --recurse                   \
      --htmldir=/perl/nmanual     \
      --htmlroot=/perl/nmanual    \
      --splithead=pod/perlipc     \
      --splititem=pod/perlfunc    \
      --libpods=perlfunc:perlguts:perlvar:perlrun:perlop \

See the documentation in installhtml for more details. It can take many minutes to execute a large installation and you should expect to see warnings like "no title", "unexpected directive" and "cannot resolve" as the files are processed. We are aware of these problems (and would welcome patches for them).

You may find it helpful to run installhtml twice. That should reduce the number of "cannot resolve" warnings.

cd pod && make tex && (process the latex files)

Some sites may also wish to make the documentation in the pod/ directory available in TeX format. Type

        (cd pod && make tex && <process the latex files>)

Minimizing the Perl installation

The following section is meant for people worrying about squeezing the Perl installation into minimal systems (for example when installing operating systems, or in really small filesystems).

Leaving out as many extensions as possible is an obvious way: Encode, with its big conversion tables, consumes a lot of space. On the other hand, you cannot throw away everything. The Fcntl module is pretty essential. If you need to do network programming, you'll appreciate the Socket module, and so forth: it all depends on what do you need to do.

In the following we offer two different slimmed down installation recipes. They are informative, not normative: the choice of files depends on what you need.

Firstly, the bare minimum to run this script

  use strict;
  use warnings;
  foreach my $f (</*>) {

in Solaris is as follows (under $Config{prefix}):


Secondly, Debian perl-base package contains the following files, size about 1.2MB in its i386 version:


Reporting Problems

If you have difficulty building perl, and none of the advice in this file helps, and careful reading of the error message and the relevant manual pages on your system doesn't help either, then you should send a message to either the comp.lang.perl.misc newsgroup or to perlbug@perl.org with an accurate description of your problem.

Please include the output of the ./myconfig shell script that comes with the distribution. Alternatively, you can use the perlbug program that comes with the perl distribution, but you need to have perl compiled before you can use it. (If you have not installed it yet, you need to run ./perl -Ilib utils/perlbug instead of a plain perlbug.)

Please try to make your message brief but clear. Trim out unnecessary information. Do not include large files (such as config.sh or a complete Configure or make log) unless absolutely necessary. Do not include a complete transcript of your build session. Just include the failing commands, the relevant error messages, and whatever preceding commands are necessary to give the appropriate context. Plain text should usually be sufficient--fancy attachments or encodings may actually reduce the number of people who read your message. Your message will get relayed to over 400 subscribers around the world so please try to keep it brief but clear.


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

Under UNIX, you can produce a documentation book in postscript form, along with its table of contents, by going to the pod/ subdirectory and running (either):

        ./roffitall -groff              # If you have GNU groff installed
        ./roffitall -psroff             # If you have psroff

This will leave you with two postscript files ready to be printed. (You may need to fix the roffitall command to use your local troff set-up.)

Note that you must have performed the installation already before running the above, since the script collects the installed files to generate the documentation.


Original author: Andy Dougherty doughera@lafayette.edu , borrowing very heavily from the original README by Larry Wall, with lots of helpful feedback and additions from the perl5-porters@perl.org folks.

If you have problems, corrections, or questions, please see "Reporting Problems" above.


This document is part of the Perl package and may be distributed under the same terms as perl itself, with the following additional request: If you are distributing a modified version of perl (perhaps as part of a larger package) please do modify these installation instructions and the contact information to match your distribution.