Omega Installation
==================

Originally based on automake's generic "Installation Instructions" which are:

Copyright (C) 1994, 1995, 1996, 1999, 2000, 2001, 2002, 2004, 2005,
2006, 2007, 2008, 2009 Free Software Foundation, Inc.

   Copying and distribution of this file, with or without modification,
are permitted in any medium without royalty provided the copyright
notice and this notice are preserved.  This file is offered as-is,
without warranty of any kind.

Prerequisites
=============

You need the following libraries installed before building Omega.  If you
install these from packages, make sure you install any corresponding -dev or
-devel packages as well:

  * zlib <https://www.zlib.net/>
  * PCRE2 <https://www.pcre.org/>
  * libmagic (which comes with the file program
    <https://www.darwinsys.com/file/>) - on RPM-based package systems, the
    package with the header in is often named file-devel

Quick Installation Guide
========================

The simplest way to compile this package is:

  1. 'cd' to the directory containing the package's source code and type
     './configure' to configure the package for your system.

     You need to make sure that xapian-config from xapian-core is on your path,
     or else pass its full path to omega's configure script:

       ./configure XAPIAN_CONFIG=/path/to/xapian-config

     Running 'configure' might take a while.  While running, it prints
     some messages telling which features it is checking for.

  2. Type 'make' to compile the package.

  3. Optionally, type 'make check' to run the self-tests that come with
     the package, using the just-built uninstalled binaries.

  4. Type 'make install' to install the programs and any data files and
     documentation.  When installing into a prefix owned by root, it is
     recommended that the package be configured and built as a regular
     user, and only the 'make install' phase executed with root
     privileges.

  5. You can remove the program binaries and object files from the
     source code directory by typing 'make clean'.  To also remove the
     files that 'configure' created (so you can compile the package for
     a different kind of computer), type 'make distclean'.  There is
     also a '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.

  6. You can also type 'make uninstall' to remove the installed files
     again.

Compilers and Options
=====================

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

   You can give 'configure' initial values for configuration parameters
by setting variables in the command line or in the environment.  Here
is an example:

     ./configure CXX=g++-4.9 CFLAGS=-O2 LIBS=-lposix

   If your system requires special flags, do let us know.  Where possible
we'd prefer configure to determine such flags by itself, but if we can't
then at least we can document the special flags to help other users of
systems like yours.

Compiling For Multiple Architectures
====================================

When using GCC on platforms which support multiple architectures, the simplest
way to select a non-default architecture is to pass a CXX setting to configure
which includes the appropriate -m option - e.g. to build for x86 on x86-64
you would configure with:

./configure CXX='g++ -m32'

On macOS 10.5 and later systems, you can create libraries and
executables that work on multiple system types--known as "fat" or
"universal" binaries--by specifying multiple '-arch' options to the
compiler but only a single '-arch' option to the preprocessor.  Like
this:

     ./configure CC="gcc -arch i386 -arch x86_64 -arch ppc -arch ppc64" \
                 CXX="g++ -arch i386 -arch x86_64 -arch ppc -arch ppc64" \
                 CPP="gcc -E" CXXCPP="g++ -E"

Building in a separate directory
================================

If you wish to perform your build in a separate directory from the source,
create and change to the build directory, and run the configure script (in
the source directory) from the build directory, like so:

  mkdir BUILD
  cd BUILD
  ../configure

Installation Names
==================

   By default, 'make install' installs the package's commands under
'/usr/local/bin', include files under '/usr/local/include', etc.  You
can specify an installation prefix other than '/usr/local' by giving
'configure' the option '--prefix=PREFIX', where PREFIX must be an
absolute file name.

   You can specify separate installation prefixes for
architecture-specific files and architecture-independent files.  If you
pass the option '--exec-prefix=PREFIX' to 'configure', the package uses
PREFIX as the prefix for installing programs and libraries.
Documentation and other data files still use the regular prefix.

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

Specifying the System Type
==========================

   There may be some features 'configure' cannot figure out
automatically, but needs to determine by the type of machine the package
will run on.  Usually, assuming the package is built to be run on the
_same_ architectures, 'configure' can figure that out, but if it prints
a message saying it cannot guess the machine type, give it the
'--build=TYPE' option.  TYPE can either be a short name for the system
type, such as 'sun4', or a canonical name which has the form:

     CPU-COMPANY-SYSTEM

where SYSTEM can have one of these forms:

     OS
     KERNEL-OS

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

   If you want to _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 '--host=TYPE'.

Sharing Defaults
================

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

Defining 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 'configure' command line, using 'VAR=value'.  For example:

     ./configure CXX=/usr/local2/bin/g++

causes the specified 'g++' to be used as the C++ compiler (unless it is
overridden in the site shell script).

'configure' Invocation
======================

'configure' recognizes the following standard options to control how it
operates:

'--help'
'-h'
     Print a summary of all of the options to 'configure', and exit.

'--version'
'-V'
     Print the version of Autoconf used to generate the 'configure'
     script, and exit.

'--cache-file=FILE'
     Enable the cache: use and save the results of the tests in FILE,
     traditionally 'config.cache'.  FILE defaults to '/dev/null' to
     disable caching.

'--config-cache'
'-C'
     Alias for '--cache-file=config.cache'.

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

'--srcdir=DIR'
     Look for the package's source code in directory DIR.  Usually
     'configure' can determine that directory automatically.

'configure' also accepts some other, not widely useful, options.  Run
'configure --help' for more details.
