7.2.5 Variables for Installation Directories

Installation directories should always be named by variables, so it is easy to install in a nonstandard place. The standard names for these variables and the values they should have in GNU packages are described below. They are based on a standard file system layout; variants of it are used in GNU/Linux and other modern operating systems.

Installers are expected to override these values when calling make (e.g., make prefix=/usr install) or configure (e.g., configure --prefix=/usr). GNU packages should not try to guess which value should be appropriate for these variables on the system they are being installed onto: use the default settings specified here so that all GNU packages behave identically, allowing the installer to achieve any desired layout.

All installation directories, and their parent directories, should be created (if necessary) before they are installed into.

These first two variables set the root for the installation. All the other installation directories should be subdirectories of one of these two, and nothing should be directly installed into these two directories.

prefix

A prefix used in constructing the default values of the variables listed below. The default value of prefix should be /usr/local. When building the complete GNU system, the prefix will be empty and /usr will be a symbolic link to /. (If you are using Autoconf, write it as ‘@prefix@’.)

Running ‘make install’ with a different value of prefix from the one used to build the program should not recompile the program.

exec_prefix

A prefix used in constructing the default values of some of the variables listed below. The default value of exec_prefix should be $(prefix). (If you are using Autoconf, write it as ‘@exec_prefix@’.)

Generally, $(exec_prefix) is used for directories that contain machine-specific files (such as executables and subroutine libraries), while $(prefix) is used directly for other directories.

Running ‘make install’ with a different value of exec_prefix from the one used to build the program should not recompile the program.

Executable programs are installed in one of the following directories.

bindir

The directory for installing executable programs that users can run. This should normally be /usr/local/bin, but write it as $(exec_prefix)/bin. (If you are using Autoconf, write it as ‘@bindir@’.)

sbindir

The directory for installing executable programs that can be run from the shell, but are only generally useful to system administrators. This should normally be /usr/local/sbin, but write it as $(exec_prefix)/sbin. (If you are using Autoconf, write it as ‘@sbindir@’.)

libexecdir

The directory for installing executable programs to be run by other programs rather than by users. This directory should normally be /usr/local/libexec, but write it as $(exec_prefix)/libexec. (If you are using Autoconf, write it as ‘@libexecdir@’.)

The definition of ‘libexecdir’ is the same for all packages, so you should install your data in a subdirectory thereof. Most packages install their data under $(libexecdir)/package-name/, possibly within additional subdirectories thereof, such as $(libexecdir)/package-name/machine/version.

Data files used by the program during its execution are divided into categories in two ways.

• Some files are normally modified by programs; others are never normally modified (though users may edit some of these).
• Some files are architecture-independent and can be shared by all machines at a site; some are architecture-dependent and can be shared only by machines of the same kind and operating system; others may never be shared between two machines.

This makes for six different possibilities. However, we want to discourage the use of architecture-dependent files, aside from object files and libraries. It is much cleaner to make other data files architecture-independent, and it is generally not hard.

Here are the variables Makefiles should use to specify directories to put these various kinds of files in:

‘datarootdir’

The root of the directory tree for read-only architecture-independent data files. This should normally be /usr/local/share, but write it as $(prefix)/share. (If you are using Autoconf, write it as ‘@datarootdir@’.) ‘datadir’’s default value is based on this variable; so are ‘infodir’, ‘mandir’, and others.

‘datadir’

The directory for installing idiosyncratic read-only architecture-independent data files for this program. This is usually the same place as ‘datarootdir’, but we use the two separate variables so that you can move these program-specific files without altering the location for Info files, man pages, etc.

This should normally be /usr/local/share, but write it as $(datarootdir). (If you are using Autoconf, write it as ‘@datadir@’.)

The definition of ‘datadir’ is the same for all packages, so you should install your data in a subdirectory thereof. Most packages install their data under $(datadir)/package-name/.

‘sysconfdir’

The directory for installing read-only data files that pertain to a single machine–that is to say, files for configuring a host. Mailer and network configuration files, /etc/passwd, and so forth belong here. All the files in this directory should be ordinary ASCII text files. This directory should normally be /usr/local/etc, but write it as $(prefix)/etc. (If you are using Autoconf, write it as ‘@sysconfdir@’.)

This directory is not the right place to install executables built by running ‘make’—they probably belong in $(libexecdir) or $(sbindir). Also do not install here files that will be modified in the normal course of their use (programs whose purpose is to change the configuration of the system excluded). Those probably belong in $(localstatedir).

‘sharedstatedir’

The directory for installing architecture-independent data files which the programs modify while they run. This should normally be /usr/local/com, but write it as $(prefix)/com. (If you are using Autoconf, write it as ‘@sharedstatedir@’.)

‘localstatedir’

The directory for installing data files which the programs modify while they run, and that pertain to one specific machine. Users should never need to modify files in this directory to configure the package’s operation; put such configuration information in separate files that go in $(datadir) or $(sysconfdir). $(localstatedir) should normally be /usr/local/var, but write it as $(prefix)/var. (If you are using Autoconf, write it as ‘@localstatedir@’.)

‘runstatedir’

The directory for installing data files which the programs modify while they run, that pertain to one specific machine, and which need not persist longer than the execution of the program—which is generally long-lived, for example, until the next reboot. PID files for system daemons are a typical use. In addition, this directory should not be cleaned except perhaps at reboot, while the general /tmp (TMPDIR) may be cleaned arbitrarily. This should normally be /var/run, but write it as $(localstatedir)/run. Having it as a separate variable allows the use of /run if desired, for example. (If you are using Autoconf 2.70 or later, write it as ‘@runstatedir@’.)

These variables specify the directory for installing certain specific types of files, if your program has them. Every GNU package should have Info files, so every program needs ‘infodir’, but not all need ‘libdir’ or ‘lispdir’.

‘includedir’

The directory for installing header files to be included by user programs with the C ‘#include’ preprocessor directive. This should normally be /usr/local/include, but write it as $(prefix)/include. (If you are using Autoconf, write it as ‘@includedir@’.)

Most compilers other than GCC do not look for header files in directory /usr/local/include. So installing the header files this way is only useful with GCC. Sometimes this is not a problem because some libraries are only really intended to work with GCC. But some libraries are intended to work with other compilers. They should install their header files in two places, one specified by includedir and one specified by oldincludedir.

‘oldincludedir’

The directory for installing ‘#include’ header files for use with compilers other than GCC. This should normally be /usr/include. (If you are using Autoconf, you can write it as ‘@oldincludedir@’.)

The Makefile commands should check whether the value of oldincludedir is empty. If it is, they should not try to use it; they should cancel the second installation of the header files.

A package should not replace an existing header in this directory unless the header came from the same package. Thus, if your Foo package provides a header file foo.h, then it should install the header file in the oldincludedir directory if either (1) there is no foo.h there or (2) the foo.h that exists came from the Foo package.

To tell whether foo.h came from the Foo package, put a magic string in the file—part of a comment—and grep for that string.

‘docdir’

The directory for installing documentation files (other than Info) for this package. By default, it should be /usr/local/share/doc/yourpkg, but it should be written as $(datarootdir)/doc/yourpkg. (If you are using Autoconf, write it as ‘@docdir@’.) The yourpkg subdirectory, which may include a version number, prevents collisions among files with common names, such as README.

‘infodir’

The directory for installing the Info files for this package. By default, it should be /usr/local/share/info, but it should be written as $(datarootdir)/info. (If you are using Autoconf, write it as ‘@infodir@’.) infodir is separate from docdir for compatibility with existing practice.

‘htmldir’

‘dvidir’

‘pdfdir’

‘psdir’

Directories for installing documentation files in the particular format. They should all be set to $(docdir) by default. (If you are using Autoconf, write them as ‘@htmldir@’, ‘@dvidir@’, etc.) Packages which supply several translations of their documentation should install them in ‘$(htmldir)/’ll, ‘$(pdfdir)/’ll, etc. where ll is a locale abbreviation such as ‘en’ or ‘pt_BR’.

‘libdir’

The directory for object files and libraries of object code. Do not install executables here, they probably ought to go in $(libexecdir) instead. The value of libdir should normally be /usr/local/lib, but write it as $(exec_prefix)/lib. (If you are using Autoconf, write it as ‘@libdir@’.)

‘lispdir’

The directory for installing any Emacs Lisp files in this package. By default, it should be /usr/local/share/emacs/site-lisp, but it should be written as $(datarootdir)/emacs/site-lisp.

If you are using Autoconf, write the default as ‘@lispdir@’. In order to make ‘@lispdir@’ work, you need the following lines in your configure.ac file:

lispdir='${datarootdir}/emacs/site-lisp'
AC_SUBST(lispdir)

‘localedir’

The directory for installing locale-specific message catalogs for this package. By default, it should be /usr/local/share/locale, but it should be written as $(datarootdir)/locale. (If you are using Autoconf, write it as ‘@localedir@’.) This directory usually has a subdirectory per locale.

Unix-style man pages are installed in one of the following:

‘mandir’

The top-level directory for installing the man pages (if any) for this package. It will normally be /usr/local/share/man, but you should write it as $(datarootdir)/man. (If you are using Autoconf, write it as ‘@mandir@’.)

‘man1dir’

The directory for installing section 1 man pages. Write it as $(mandir)/man1.

‘man2dir’

The directory for installing section 2 man pages. Write it as $(mandir)/man2

‘…’

Don’t make the primary documentation for any GNU software be a man page. Write a manual in Texinfo instead. Man pages are just for the sake of people running GNU software on Unix, which is a secondary application only.

‘manext’

The file name extension for the installed man page. This should contain a period followed by the appropriate digit; it should normally be ‘.1’.

‘man1ext’

The file name extension for installed section 1 man pages.

‘man2ext’

The file name extension for installed section 2 man pages.

‘…’

Use these names instead of ‘manext’ if the package needs to install man pages in more than one section of the manual.

And finally, you should set the following variable:

‘srcdir’

The directory for the sources being compiled. The value of this variable is normally inserted by the configure shell script. (If you are using Autoconf, use ‘srcdir = @srcdir@’.)

For example:

# Common prefix for installation directories.
# NOTE: This directory must exist when you start the install.
prefix = /usr/local
datarootdir = $(prefix)/share
datadir = $(datarootdir)
exec_prefix = $(prefix)
# Where to put the executable for the command 'gcc'.
bindir = $(exec_prefix)/bin
# Where to put the directories used by the compiler.
libexecdir = $(exec_prefix)/libexec
# Where to put the Info files.
infodir = $(datarootdir)/info

If your program installs a large number of files into one of the standard user-specified directories, it might be useful to group them into a subdirectory particular to that program. If you do this, you should write the install rule to create these subdirectories.

Do not expect the user to include the subdirectory name in the value of any of the variables listed above. The idea of having a uniform set of variable names for installation directories is to enable the user to specify the exact same values for several different GNU packages. In order for this to be useful, all the packages must be designed so that they will work sensibly when the user does so.

At times, not all of these variables may be implemented in the current release of Autoconf and/or Automake; but as of Autoconf 2.60, we believe all of them are. When any are missing, the descriptions here serve as specifications for what Autoconf will implement. As a programmer, you can either use a development version of Autoconf or avoid using these variables until a stable release is made which supports them.