@c This file is included by autoconf.texi and is used to produce
@c the INSTALL file.

@node Basic Installation
@section Basic Installation

These are generic installation instructions.

The @code{configure} shell script attempts to guess correct values for
various system-dependent variables used during compilation.  It uses
those values to create a @file{Makefile} in each directory of the
package.  It may also create one or more @file{.h} files containing
system-dependent definitions.  Finally, it creates a shell script
@file{config.status} that you can run in the future to recreate the
current configuration, and a file @file{config.log} containing compiler
output (useful mainly for debugging @code{configure}).

It can also use an optional file (typically called @file{config.cache}
and enabled with @option{--cache-file=config.cache} or simply
@option{-C}) that saves the results of its tests to speed up
reconfiguring.  (Caching is disabled by default to prevent problems with
accidental use of stale cache files.)

If you need to do unusual things to compile the package, please try to
figure out how @code{configure} could check whether to do them, and mail
diffs or instructions to the address given in the @file{README} so they
can be considered for the next release.  If you are using the cache, and
at some point @file{config.cache} contains results you don't want to
keep, you may remove or edit it.

The file @file{configure.in} is used to create @file{configure} by a
program called @code{autoconf}.  You only need @file{configure.in} if
you want to change it or regenerate @file{configure} using a newer
version of @code{autoconf}.

@noindent
The simplest way to compile this package is:

@enumerate
@item
@code{cd} to the directory containing the package's source code and type
@samp{./configure} to configure the package for your system.  If you're
using @code{csh} on an old version of System V, you might need to type
@samp{sh ./configure} instead to prevent @code{csh} from trying to
execute @code{configure} itself.

Running @code{configure} takes awhile.  While running, it prints some
messages telling which features it is checking for.

@item
Type @samp{make} to compile the package.

@item
Optionally, type @samp{make check} to run any self-tests that come with
the package.

@item
Type @samp{make install} to install the programs and any data files and
documentation.

@item
You can remove the program binaries and object files from the source code
directory by typing @samp{make clean}.  To also remove the files that
@code{configure} created (so you can compile the package for a different
kind of computer), type @samp{make distclean}.  There is also a
@samp{make maintainer-clean} target, but that is intended mainly for the
package's developers.  If you use it, you may have to get all sorts of
other programs in order to regenerate files that came with the distribution.
@end enumerate

@node Compilers and Options
@section Compilers and Options

Some systems require unusual options for compilation or linking that the
@code{configure} script does not know about.  Run @samp{./configure
--help} for details on some of the pertinent environment variables.

You can give @code{configure} initial values for variables by setting
them in the environment.  You can do that on the command line like this:

@example
./configure CC=c89 CFLAGS=-O2 LIBS=-lposix
@end example

@xref{Environment Variables}, for more details.


@node Multiple Architectures
@section Compiling For Multiple Architectures

You can compile the package for more than one kind of computer at the
same time, by placing the object files for each architecture in their
own directory.  To do this, you must use a version of @code{make} that
supports the @code{VPATH} variable, such as GNU @code{make}.  @code{cd}
to the directory where you want the object files and executables to go
and run the @code{configure} script.  @code{configure} automatically
checks for the source code in the directory that @code{configure} is in
and in @file{..}.

If you have to use a @code{make} that does not support the @code{VPATH}
variable, you have to compile the package for one architecture at a time
in the source code directory.  After you have installed the package for
one architecture, use @samp{make distclean} before reconfiguring for
another architecture.

@node Installation Names
@section Installation Names

By default, @samp{make install} will install the package's files in
@file{/usr/local/bin}, @file{/usr/local/man}, etc.  You can specify an
installation prefix other than @file{/usr/local} by giving
@code{configure} the option @option{--prefix=@var{path}}.

You can specify separate installation prefixes for architecture-specific
files and architecture-independent files.  If you give @code{configure}
the option @option{--exec-prefix=@var{path}}, the package will use
@var{path} as the prefix for installing programs and libraries.
Documentation and other data files will still use the regular prefix.

In addition, if you use an unusual directory layout you can give options
like @option{--bindir=@var{path}} to specify different values for
particular kinds of files.  Run @samp{configure --help} for a list of
the directories you can set and what kinds of files go in them.

If the package supports it, you can cause programs to be installed with
an extra prefix or suffix on their names by giving @code{configure} the
option @option{--program-prefix=@var{PREFIX}} or
@option{--program-suffix=@var{SUFFIX}}.

@node Optional Features
@section Optional Features

Some packages pay attention to @option{--enable-@var{feature}} options
to @code{configure}, where @var{feature} indicates an optional part of
the package.  They may also pay attention to
@option{--with-@var{package}} options, where @var{package} is something
like @samp{gnu-as} or @samp{x} (for the X Window System).  The
@file{README} should mention any @option{--enable-} and @option{--with-}
options that the package recognizes.

For packages that use the X Window System, @code{configure} can usually
find the X include and library files automatically, but if it doesn't,
you can use the @code{configure} options @option{--x-includes=@var{dir}}
and @option{--x-libraries=@var{dir}} to specify their locations.

@node System Type
@section Specifying the System Type

There may be some features @code{configure} cannot figure out
automatically, but needs to determine by the type of host the package
will run on.  Usually @code{configure} can figure that out, but if it
prints a message saying it cannot guess the host type, give it the
@option{--build=@var{type}} option.  @var{type} can either be a short
name for the system type, such as @samp{sun4}, or a canonical name which
has the form:

@example
@var{cpu}-@var{company}-@var{system}
@end example

@noindent
where @var{system} can have one of these forms:

@example
@var{os}
@var{kernel}-@var{os}
@end example

See the file @file{config.sub} for the possible values of each field.
If @file{config.sub} isn't included in this package, then this package
doesn't need to know the host type.

If you are @emph{building} compiler tools for cross-compiling, you should
use the @option{--target=@var{type}} option to select the type of system
they will produce code for.

If you want to @emph{use} a cross compiler, that generates code for a
platform different from the build platform, you should specify the host
platform (i.e., that on which the generated programs will eventually be
run) with @option{--host=@var{type}}.  In this case, you should also
specify the build platform with @option{--build=@var{type}}, because, in
this case, it may not be possible to guess the build platform (it
sometimes involves compiling and running simple test programs, and this
can't be done if the compiler is a cross compiler).

@node Sharing Defaults
@section Sharing Defaults

If you want to set default values for @code{configure} scripts to share,
you can create a site shell script called @file{config.site} that gives
default values for variables like @code{CC}, @code{cache_file}, and
@code{prefix}.  @code{configure} looks for
@file{@var{prefix}/share/config.site} if it exists, then
@file{@var{prefix}/etc/config.site} if it exists.  Or, you can set the
@code{CONFIG_SITE} environment variable to the location of the site
script.  A warning: not all @code{configure} scripts look for a site
script.

@node Environment Variables
@section Environment Variables

Variables not defined in a site shell script can be set in the
environment passed to configure.  However, some packages may run
configure again during the build, and the customized values of these
variables may be lost.  In order to avoid this problem, you should set
them in the @code{configure} command line, using @samp{VAR=value}.  For
example:

@example
./configure CC=/usr/local2/bin/gcc
@end example

@noindent
will cause the specified gcc to be used as the C compiler (unless it is
overridden in the site shell script).


@node configure Invocation
@section @code{configure} Invocation

@code{configure} recognizes the following options to control how it
operates.

@table @option
@item --help
@itemx -h
Print a summary of the options to @code{configure}, and exit.

@item --version
@itemx -V
Print the version of Autoconf used to generate the @code{configure}
script, and exit.

@item --cache-file=@var{file}
@cindex Cache, enabling
Enable the cache: use and save the results of the tests in @var{file},
traditionally @file{config.cache}.  @var{file} defaults to
@file{/dev/null} to disable caching.

@item --config-cache
@itemx -C
Alias for @option{--cache-file=config.cache}.

@item --quiet
@itemx --silent
@itemx -q
Do not print messages saying which checks are being made.  To suppress
all normal output, redirect it to @file{/dev/null} (any error messages
will still be shown).

@item --srcdir=@var{dir}
Look for the package's source code in directory @var{dir}.  Usually
@code{configure} can determine that directory automatically.
@end table

@noindent
@code{configure} also accepts some other, not widely useful, options.
Run @samp{configure --help} for more details.