Install - Build and Installation guide for perl5.


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

        rm -f
        sh Configure
        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.

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

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.

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 hint file.)

WARNING: This version is not binary compatible with Perl 5.004.

Starting with Perl 5.004_50 there were many deep and far-reaching changes to the language internals. If you have dynamically loaded extensions that you built under perl 5.003 or 5.004, you can continue to use them with 5.004, but you will need to rebuild and reinstall those extensions to use them 5.005. See the discussions below on Coexistence with earlier versions of perl5 and Upgrading from 5.004 to 5.005 for more details.

The standard extensions supplied with Perl will be handled automatically.

In a related issue, old extensions may possibly be affected by the changes in the Perl language in the current release. Please see pod/perldelta.pod for a description of what's changed.

Space Requirements

The complete perl5 source tree takes up about 10 MB of disk space. The complete tree after completing make takes roughly 20 MB, though the actual total is likely to be quite system-dependent. The installation directories need something on the order of 10 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 and files.

The results of a Configure run are stored in the and 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 Simply remove it or rename it, e.g.


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

Also, be careful to check your architecture name. Some Linux systems (such as Debian) use i386, while others may use i486, i586, or i686. If you pick up a precompiled binary, it might not use the same name.

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

If your reason to reuse your old is to save your particular installation choices, then you can probably achieve the same effect by using the new file. See the section on Site-wide Policy settings below.

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. 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.

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, for example, 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.

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

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

        sh Configure -Dprefix=/opt/perl

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

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

It may seem obvious to say, 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, of overwriting a version of perl supplied by your vendor. 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.

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.

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

        sh Configure -des

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.

Cross compiling is not supported.

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


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.) B, DynaLoader, Fcntl, IO, and attrs are always built by default. Configure does not contain code to test for POSIX compliance, so POSIX is always built by default as well. If you wish to skip POSIX, you can set the Configure variable useposix=false either in a hint file or from the Configure command line. Similarly, the Opcode extension is always built by default, but you can skip it by setting the Configure variable useopcode=false either in a hint file for from the command line.

You can learn more about each of these 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 each extension:

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

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 version 2.

If you re-use your old 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 Unix systems do) remember that these extensions do not increase the size of your perl executable, nor do they impact start-up time, so you probably might as well build all the ones that will work on your system.

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.

Note: If your database header (.h) files are not in a directory normally searched by your C compiler, then you will need to include the appropriate -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 examples 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. If you want to accept the defaults for all the questions and have Configure print out only terse messages, then you can just run

        sh Configure -des

and Configure should include the GDBM_File extension automatically.

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

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

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.

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.

By default, Configure will use the following directories for library files for 5.005 (archname is a string like sun4-sunos, determined by Configure).

    Configure variable          Default value
        $archlib        /usr/local/lib/perl5/5.005/archname
        $privlib        /usr/local/lib/perl5/5.005
        $sitearch       /usr/local/lib/perl5/site_perl/5.005/archname
        $sitelib        /usr/local/lib/perl5/site_perl/5.005

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

By default, Configure will use the following directories for manual pages:

    Configure variable          Default value
        $man1dir        /usr/local/man/man1
        $man3dir        /usr/local/lib/perl5/man/man3

(Actually, Configure recognizes the SVR3-style /usr/local/man/l_man/man1 directories, if present, and uses those instead.)

The module man pages are stuck in that strange spot so that they don't collide with other man pages stored in /usr/local/man/man3, and so that Perl's man pages don't hide system man pages. On some systems, man less would end up calling up Perl's module man page, rather than the less program. (This default location will likely change to /usr/local/man/man3 in a future release of perl.)

Note: Many users prefer to store the module man pages in /usr/local/man/man3. You can do this from the command line with

        sh Configure -Dman3dir=/usr/local/man/man3

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

        sh Configure -Dman3ext=3pm

If you specify a prefix that contains the string ``perl'', then the directory structure is simplified. For example, if you Configure with -Dprefix=/opt/perl, then the defaults for 5.005 are

    Configure variable          Default value
        $archlib        /opt/perl/lib/5.005/archname
        $privlib        /opt/perl/lib/5.005
        $sitearch       /opt/perl/lib/site_perl/5.005/archname
        $sitelib        /opt/perl/lib/site_perl/5.005

        $man1dir        /opt/perl/man/man1
        $man3dir        /opt/perl/man/man3

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

The directories under site_perl are empty, but are intended to be used for installing local or site-wide extensions. Perl will automatically look in these directories.

In order to support using things like #!/usr/local/bin/perl5.005 after a later version is released, architecture-dependent libraries are stored in a version-specific directory, such as /usr/local/lib/perl5/archname/5.005/.

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.

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

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 may also wish to install perl into a different directory and use that management software to move perl to its final destination. This section describes how to do this. Someday, Configure may support an option -Dinstallprefix=/foo to simplify this.

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

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

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

    sh Configure -des
    make test
    make install

Beware, though, that if you go to try to install new add-on extensions, 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. Here's one way to do that:

    # Set up config.over to install perl into a different directory,
    # e.g. /tmp/perl5 (see previous part).
    sh Configure -des
    make test
    make install
    cd /tmp/perl5
    # Edit $archlib/ to change all the
    # install* variables back to reflect where everything will
    # really be installed.
    # Edit any of the scripts in $scriptdir to have the correct
    # #!/wherever/perl line.
    tar cvf ../perl5-archive.tar .
    # Then, on each machine where you want to install perl,
    cd /usr/local  # Or wherever you specified as $prefix
    tar xvf perl5-archive.tar

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 file. If you want to build perl on another system using the same policy defaults, simply copy the 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

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

Further information is in the Policy_sh.SH file itself.

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, perl5.005 can be compiled to use threads. To enable this, read the file README.threads, and then try

        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.

Selecting File IO mechanisms

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

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

        sh Configure -Duseperlio

or interactively at the appropriate Configure prompt.

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

  1. .

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

    This option requires the 'sfio' package to have been built and installed. A (fairly old) version of sfio is in CPAN.

    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.

    You can test if you have this problem by trying the following shell script. (You may have to add some extra cflags and libraries. A portable version of this may eventually make its way into Configure.)

        cat > try.c <<'EOCP'
        #include <stdio.h>
        main() { printf("42\n"); }
        cc -o try try.c -lsfio
        if test X$val = X42; then
            echo "Your sfio looks ok"
            echo "Your sfio has the exit problem."

    If you have this problem, the fix is to go back to your sfio sources and correct iffe's guess about atexit.

    There also might be a more recent release of Sfio that fixes your problem.

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

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

    You select this option via:

            sh Configure -Duseperlio -Uusesfio

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

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 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 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, 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 Your system and typical applications may well give quite different results.

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

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

You can elect to build a shared libperl by

        sh Configure -Duseshrplib

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


for Bourne-style shells, or

   setenv LD_LIBRARY_PATH `pwd`

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

There is also an potential problem with the shared perl library if you want to have more than one ``flavor'' of the same version of perl (e.g. with and without -DDEBUGGING). For example, suppose you build and install a standard Perl 5.004 with a shared library. Then, suppose you try to build Perl 5.004 with -DDEBUGGING enabled, but everything else the same, including all the installation directories. How can you ensure that your newly built perl will link with your newly built rather with the installed 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, namely archlib, archlib_exp, and installarchlib, 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 is very fast but somewhat wasteful of space. On the other hand, your system's malloc function may be a bit slower but also a bit more frugal. However, as of 5.004_68, perl's malloc has been optimized for the typical requests from perl, so there's a chance that it may be both faster and use less memory.

For many uses, speed is probably the most important consideration, so the default behavior (for most systems) is to use the malloc supplied with perl. However, if you will be running very large applications (e.g. Tk or PDL) or 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 might wish to use your system's malloc. (Or, you might wish to explore the malloc flags discussed below.)

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.

Malloc Performance Flags

If you are using Perl's malloc, you may add one or more of the following items to your ccflags variable to change its behavior. You can find out more about these and other flags by reading the commentary near the top of the malloc.c source. The defaults should be fine for nearly everyone.


Undefined by default. Defining it returns malloc to the version used in Perl 5.004.


Undefined by default. Defining it in addition to NO_FANCY_MALLOC returns malloc to the version used in Perl version 5.000.

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 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 If you want to reuse your old, 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 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 Perl library.

Other Compiler Flags

For most users, all of the Configure defaults are fine. However, you can change a number of factors in the way perl is built by adding appropriate -D directives to your ccflags variable in

For example, you can replace the rand() and srand() functions in the perl source by any other random number generator by a trick such as the following (this should all be on one line):

        sh Configure -Dccflags='-Dmy_rand=random -Dmy_srand=srandom' \

or you can use the drand48 family of functions with

        sh Configure -Dccflags='-Dmy_rand=lrand48 -Dmy_srand=srand48' \

or by adding the -D flags to your ccflags at the appropriate Configure prompt. (Read pp.c to see how this works.)

You should also run Configure interactively to verify that a hint file doesn't inadvertently override your ccflags setting. (Hints files shouldn't do that, but some might.)

What if it doesn't work?

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/ 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, 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 Simply remove it or rename it, e.g. mv 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

    Propagating your changes to

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

            sh Configure -S

    You will then have to rebuild by running

            make depend

    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 is created. You have to be careful with this, however, as Configure does no checking that your changes make sense. See the section on Changing the installation directory for an example.


    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

    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 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_H to config.h and edit the config.h to reflect your system's peculiarities. You'll probably also have to extensively modify the extension building mechanism.

    Porting information

    Specific information for the OS/2, Plan9, VMS and Win32 ports is in the corresponding README files and subdirectories. Additional information, including a glossary of all those variables, is in the Porting subdirectory.

    Ports for other systems may also be available. You should check out for current information on ports to various other operating systems.

  • 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 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.

    If you can't compile successfully, try some of the following ideas. If none of them help, and careful reading of the error message and the relevant manual pages on your system doesn't help, you can send a message to either the comp.lang.perl.misc newsgroup or to with an accurate description of your problem. 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.

    malloc duplicates

    If you get duplicates upon linking for malloc et al, add -DEMBEDMYMALLOC to your ccflags variable in


    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 The problem is usually solved by running fixincludes correctly. If you do change, don't forget to propagate your changes (see Propagating your changes to 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.

    Solaris and SunOS dynamic loading

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

    One convenient way to ensure you are not using GNU as and ld is to invoke Configure with

        sh Configure -Dcc='gcc -B/usr/ccs/bin/'

    for Solaris systems. For a SunOS system, you must use -B/bin/ instead.

    Alternatively, recent versions of GNU ld reportedly work if you include -Wl,-export-dynamic in the ccdlflags variable in ./perl: fatal: relocation error:

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


    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 it should build fine with LD_LIBRARY_PATH unset, though that may depend on details of your local set-up.

    dlopen: stub interception failed

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

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

    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

    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 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 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.


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



            optimize=' '

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


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

    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.


    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 -DCRIPPLED_CC, -K or -g, and undef LSTAT.

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

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

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

    make test

    This will run the regression tests on the perl you just made (you should run plain 'make' before 'make test' otherwise you won't have a complete build). 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).

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


    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.

    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. Specifically, in perl5.004_64, tests 74 and 78 have been reported to fail on some systems. On my SparcStation IPC with 8 MB of RAM, test 78 will fail if the system is running any other significant tasks at the same time.

    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.

    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

    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.
            pod2man, and
            splain          Describe Perl warnings and errors

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

    Installperl will also create the library directories $siteperl and $sitearch listed in Usually, these are something like


    where archname is something like sun4-sunos. These directories will be used for installing extensions.

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

    Coexistence with earlier versions of perl5

    WARNING: The upgrade from 5.004_0x to 5.005 is going to be a bit tricky. See Upgrading from 5.004 to 5.005 below.

    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.

    Most extensions will probably not need to be recompiled to use with a newer version of perl. Here is how it is supposed to work. (These examples assume you accept all the Configure defaults.)

    The directories searched by version 5.005 will be

        Configure variable          Default value
            $archlib        /usr/local/lib/perl5/5.005/archname
            $privlib        /usr/local/lib/perl5/5.005
            $sitearch       /usr/local/lib/perl5/site_perl/5.005/archname
            $sitelib        /usr/local/lib/perl5/site_perl/5.005

    while the directories searched by version 5.005_01 will be

            $archlib        /usr/local/lib/perl5/5.00501/archname
            $privlib        /usr/local/lib/perl5/5.00501
            $sitearch       /usr/local/lib/perl5/site_perl/5.005/archname
            $sitelib        /usr/local/lib/perl5/site_perl/5.005

    When you install an add-on extension, it gets installed into $sitelib (or $sitearch if it is architecture-specific). This directory deliberately does NOT include the sub-version number (01) so that both 5.005 and 5.005_01 can use the extension. Only when a perl version changes to break backwards compatibility will the default suggestions for the $sitearch and $sitelib version numbers be increased.

    However, if you do run into problems, and you want to continue to use the old version of perl along with your extension, move those extension files to the appropriate version directory, such as $privlib (or $archlib). (The extension's .packlist file lists the files installed with that extension. For the Tk extension, for example, the list of files installed is in $sitearch/auto/Tk/.packlist.) Then use your newer version of perl to rebuild and re-install the extension into $sitelib. This way, Perl 5.005 will find your files in the 5.005 directory, and newer versions of perl will find your newer extension in the $sitelib directory. (This is also why perl searches the site-specific libraries last.)

    Alternatively, if you are willing to reinstall all your extensions every time you upgrade perl, then you can include the subversion number in $sitearch and $sitelib when you run Configure.

    Maintaining completely separate versions

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

            sh Configure -Dprefix=/opt/perl5.004

    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. 5.004 for all 5.004_0x 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 5.004 to 5.005

    Extensions built and installed with versions of perl prior to 5.004_50 will need to be recompiled to be used with 5.004_50 and later. You will, however, be able to continue using 5.004 even after you install 5.005. The 5.004 binary will still be able to find the extensions built under 5.004; the 5.005 binary will look in the new $sitearch and $sitelib directories, and will not find them.

    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.

    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>)

    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 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.)

    You might also find helpful information in the Porting directory of the perl distribution.


    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 , borrowing very heavily from the original README by Larry Wall, with lots of helpful feedback and additions from the 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.

    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.


    $Id: INSTALL,v 1.42 1998/07/15 18:04:44 doughera Released $


    We are painfully aware that these documents may contain incorrect links and misformatted HTML. Such bugs lie in the automatic translation process that automatically created the hundreds and hundreds of separate documents that you find here. Please do not report link or formatting bugs, because we cannot fix per-document problems. The only bug reports that will help us are those that supply working patches to the installhtml or pod2html programs, or to the Pod::HTML module itself, for which I and the entire Perl community will shower you with thanks and praises.

    If rather than formatting bugs, you encounter substantive content errors in these documents, such as mistakes in the explanations or code, please use the perlbug utility included with the Perl distribution.

    --Tom Christiansen, Perl Documentation Compiler and Editor

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