Re: INSTALL updates

Installation Instructions

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Basic Installation
Compilers and Options
Compiling For Multiple Architectures
Installation Names
Optional Features
Specifying a System Type
Creating binaries for a different system type
Fixing a “cannot guess build type” error
Configuration options specific to a compiler
Sharing Defaults
Defining Variables
configure Invocation

Basic Installation

Briefly, the following shell commands:

test -f configure || ./bootstrap
./configure
make
make install

should configure, build, and install this package. The ./bootstrap line is intended for developers; you can omit it when building from a distribution tarball.

The following more-detailed instructions are generic; see the README file for instructions specific to this package. Some packages provide this INSTALL file but do not implement all of the features documented below. The lack of an optional feature in a given package is not necessarily a bug. More recommendations for GNU packages can be found in Makefile Conventions in GNU Coding Standards.

If the bootstrap shell script exists, it attempts to build the configure shell script and related files, perhaps by downloading other software components from the network, and by using developer tools that are less commonly installed. Because the output of bootstrap is system-independent, it is normally run by a package developer so that its output can be put into the distribution tarball and ordinary builders and users need not run bootstrap. Some packages have commands like ./autopull.sh and ./autogen.sh that you can run instead of ./bootstrap, for more fine-grained control over bootstrapping.

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

It can also use an optional file (typically called config.cache and enabled with --cache-file=config.cache or simply -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 configure could check whether to do them, and mail diffs or instructions to the address given in the README so they can be considered for the next release. If you are using the cache, and at some point config.cache contains results you don’t want to keep, you may remove or edit it.

The file configure.ac (or configure.in) is used to create configure by a program called autoconf. You need configure.ac if you want to change it or regenerate configure using a newer version of autoconf.

The simplest way to compile this package is:

cd to the directory containing the package’s source code.
If this is a developer checkout and file ‘configure’ does not yet exist, type ‘./bootstrap’ to create it. You may need special developer tools and network access to bootstrap.
Type ‘./configure’ to configure the package for your system.
Running configure might take a while. While running, it prints some messages telling which features it is checking for.
Type ‘make’ to compile the package.
Optionally, type ‘make check’ to run any self-tests that come with the package, generally using the just-built uninstalled binaries.
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.
Optionally, type ‘make installcheck’ to repeat any self-tests, but this time using the binaries in their final installed location. This target does not install anything. Running this target as a regular user, particularly if the prior ‘make install’ required root privileges, verifies that the installation completed correctly.
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.
Often, you can also type ‘make uninstall’ to remove the installed files again. In practice, not all packages have tested that uninstallation works correctly, even though it is required by the GNU Coding Standards.
Some packages, particularly those that use Automake, provide ‘make distcheck’, which can by used by developers to test that all other targets like ‘make install’ and ‘make uninstall’ work correctly. This target is generally not run by end users.

Compilers and Options

Some systems 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 CC=gcc CFLAGS=-g LIBS=-lposix

See Defining Variables and Preset Output Variables in Autoconf for more details.

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 can use GNU make. cd to the directory where you want the object files and executables to go and run the configure script. configure automatically checks for the source code in the directory that configure is in and in ... This is known as a VPATH build.

With a non-GNU make, it is safer 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 ‘make distclean’ before reconfiguring for another architecture.

Some platforms, notably macOS, support “fat” or “universal” binaries, where a single binary can execute on different architectures. On these platforms you can configure and compile just once, with options specific to that platform.

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. In general, the default for these options is expressed in terms of ‘${prefix}’, so that specifying just --prefix will affect all of the other directory specifications that were not explicitly provided.

The most portable way to affect installation locations is to pass the correct locations to configure; however, many packages provide one or both of the following shortcuts of passing variable assignments to the ‘make install’ command line to change installation locations without having to reconfigure or recompile.

The first method involves providing an override variable for each affected directory. For example, ‘make install prefix=/alternate/directory’ will choose an alternate location for all directory configuration variables that were expressed in terms of ‘${prefix}’. Any directories that were specified during configure, but not in terms of ‘${prefix}’, must each be overridden at install time for the entire installation to be relocated. The approach of makefile variable overrides for each directory variable is required by the GNU Coding Standards, and ideally causes no recompilation. However, some platforms have known limitations with the semantics of shared libraries that end up requiring recompilation when using this method, particularly noticeable in packages that use GNU Libtool.

The second method involves providing the ‘DESTDIR’ variable. For example, ‘make install DESTDIR=/alternate/directory’ will prepend ‘/alternate/directory’ before all installation names. The approach of ‘DESTDIR’ overrides is not required by the GNU Coding Standards, and does not work on platforms that have drive letters. On the other hand, it does better at avoiding recompilation issues, and works well even when some directory options were not specified in terms of ‘${prefix}’ at configure time.

Optional Features

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

Some packages pay attention to --enable-feature and --disable-feature options to configure, where feature indicates an optional part of the package. They may also pay attention to --with-package and --without-package options, where package is something like ‘gnu-ld’. ‘./configure --help’ should mention the --enable-... and --with-... options that the package recognizes.

Some packages offer the ability to configure how verbose the execution of make will be. For these packages, running ‘./configure --enable-silent-rules’ sets the default to minimal output, which can be overridden with make V=1; while running ‘./configure --disable-silent-rules’ sets the default to verbose, which can be overridden with make V=0.

Specifying a System Type

The following sections go into details regarding situations where you may have to specify a system type, either through the option --host=type, or through the option --build=type, or – in the case of compilers – through --target=type.

A system type type can either be a short name like ‘mingw64’, or a canonical name like ‘x86_64-pc-linux-gnu’ 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 any machine type.

The file config.sub is a program that validates and canonicalizes a system type. It can do canonicalization, as in

$ sh config.sub x86_64-linux
x86_64-pc-linux-gnu
$ sh config.sub arm64-linux
aarch64-unknown-linux-gnu

It also validates the parts. For example, this interaction tells you that “crusoe” is not a valid cpu architecture name:

$ sh config.sub crusoe-linux
Invalid configuration `crusoe-linux': machine `crusoe-unknown' not recognized

Creating binaries for a different system type

When you want to create binaries that will run on a different machine type than the one you are building on, you need to specify both

a --host=type option, specifying the machine type on which the binaries shall run,
compiler variables (CC for the C compiler, CXX for the C++ compiler, and so on), pointing to compilers that generate object code for that machine type.

For example, to create binaries intended to run on a 64-bit ARM processor:

./configure --host=aarch64-linux-gnu \
            CC=aarch64-linux-gnu-gcc CXX=aarch64-linux-gnu-g++

If you do this on a machine that can execute such binaries (e.g. by virtue of the qemu-aarch64 program, system libraries for that architecture under $QEMU_LD_PREFIX, and a Linux binfmt_misc configuration), the build behaves like a native build. If not, the build is a cross-build, in the sense that configure will make cross-compilation guesses instead of running test programs, and “make check” will not work.

Fixing a “cannot guess build type” error

In rare cases, it may happen that configure fails with the error message “cannot guess build type”. This error means that the files config.guess and config.sub don’t recognize the type of the system on which you are building. In this case, first fetch the newest versions of these files, from https://git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=config.guess and https://git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=config.sub, respectively, and use these as drop-in replacement for the files config.guess and config.sub that were shipped with this package.

If this resolves the problem, feel free to report the solution to the maintainers of this package.

Otherwise, it means that your system is not yet supported by config.guess and config.sub. As a workaround, you can use a configure option --build=type, where type comes closest to your system type. Also, you’re welcome to file a report to config-patches@gnu.org.

Configuration options specific to a compiler

If you are building a compiler, and this compiler should generate code for a system type that is different from the one on which the compiler binaries shall run on, use the option --target=type to select the type of system for which the compiler should produce code.

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 CC=/usr/local2/bin/gcc

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

Unfortunately, this technique does not work for CONFIG_SHELL due to an Autoconf limitation. Until the limitation is lifted, you can use this workaround:

CONFIG_SHELL=/bin/bash ./configure CONFIG_SHELL=/bin/bash

`configure` Invocation

configure recognizes the following options to control how it operates.

--help
-h: Print a summary of all of the options to configure, and exit.
--help=short
--help=recursive: Print a summary of the options unique to this package’s configure, and exit. The short variant lists options used only in the top level, while the recursive variant lists options also present in any nested packages.
--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.
--srcdir=dir: Look for the package’s source code in directory dir. Usually configure can determine that directory automatically.
--prefix=dir: Use dir as the installation prefix. Installation Names for more details, including other options available for fine-tuning the installation locations.
--host=type: Build binaries for architecture type. Specifying a System Type and Creating binaries for a different system type for more details.
--enable-feature
--disable-feature: Enable or disable the optional feature. See Optional Features.
--with-package
--without-package: Use or omit package when building. See Optional Features.
--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).
--no-create
-n: Run the configure checks, but stop before creating any output files.

configure also recognizes several environment variables, and accepts some other, less widely useful, options. Run ‘configure --help’ for more details.

From:	Bruno Haible
Subject:	Re: INSTALL updates
Date:	Fri, 23 Jun 2023 17:42:07 +0200