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[emacs.git] / INSTALL

GNU Emacs Installation Guide
Copyright (C) 1992, 1994, 1996-1997, 2000-2020 Free Software Foundation,
Inc.
See the end of the file for license conditions.


This file contains general information on building GNU Emacs.
For more information specific to the MS-Windows, GNUstep/macOS, and
MS-DOS ports, also read the files nt/INSTALL, nextstep/INSTALL, and
msdos/INSTALL.  For information about building from a repository checkout
(rather than a release), also read the file INSTALL.REPO.


BASIC INSTALLATION

On most Unix systems, you build Emacs by first running the 'configure'
shell script.  This attempts to deduce the correct values for
various system-dependent variables and features, and find the
directories where certain system headers and libraries are kept.
In a few cases, you may need to explicitly tell configure where to
find some things, or what options to use.

'configure' creates a 'Makefile' in several subdirectories, and a
'src/config.h' file containing system-dependent definitions.
Running the 'make' utility then builds the package for your system.

Building Emacs requires GNU make, <https://www.gnu.org/software/make/>.
On most systems that Emacs supports, this is the default 'make' program.

Here's the procedure to build Emacs using 'configure' on systems which
are supported by it.  In some cases, if the simplified procedure fails,
you might need to use various non-default options, and maybe perform
some of the steps manually.  The more detailed description in the other
sections of this guide will help you do that, so please refer to those
sections if you need to.

  1.  Obtain and unpack the Emacs release, with commands like this:

                 wget https://ftp.gnu.org/gnu/emacs/emacs-VERSION.tar.xz
                 tar -xf emacs-VERSION.tar.xz

      where VERSION is the Emacs version number.

  2a. 'cd' to the directory where you unpacked Emacs and invoke the
      'configure' script:

                 ./configure

  2b. Alternatively, create a separate directory, outside the source
      directory, where you want to build Emacs, and invoke 'configure'
      from there:

                 SOURCE-DIR/configure

      where SOURCE-DIR is the top-level Emacs source directory.

  3. When 'configure' finishes, it prints several lines of details
     about the system configuration.  Read those details carefully
     looking for anything suspicious, such as wrong CPU and operating
     system names, wrong places for headers or libraries, missing
     libraries that you know are installed on your system, etc.

     If you find anything wrong, you may have to pass to 'configure'
     one or more options specifying the explicit machine configuration
     name, where to find various headers and libraries, etc.
     Refer to the section DETAILED BUILDING AND INSTALLATION below.

     If 'configure' didn't find some image support libraries, such as
     Xpm and jpeg, refer to "Image support libraries" below.

     If the details printed by 'configure' don't make any sense to
     you, but there are no obvious errors, assume that 'configure' did
     its job and proceed.

  4. Invoke the 'make' program:

                 make

  5. If 'make' succeeds, it will build an executable program 'emacs'
     in the 'src' directory.  You can try this program, to make sure
     it works:

                 src/emacs -Q

     To test Emacs further (intended mostly to help developers):

                 make check

  6. Assuming that the program 'src/emacs' starts and displays its
     opening screen, you can install the program and its auxiliary
     files into their installation directories:

                 make install

  You are now ready to use Emacs.  If you wish to conserve space,
  you may remove the program binaries and object files from the
  directory where you built Emacs:

                 make clean

  You can delete the entire build directory if you do not plan to
  build Emacs again, but it can be useful to keep for debugging.
  If you want to build Emacs again with different configure options,
  first clean the source directories:

                make distclean

  Note that the install automatically saves space by compressing
  (provided you have the 'gzip' program) those installed Lisp source (.el)
  files that have corresponding .elc versions, as well as the Info files.

  You can read a brief summary about common make targets:

                make help

ADDITIONAL DISTRIBUTION FILES

* Complex Text Layout support libraries

On GNU and Unix systems, Emacs needs the optional libraries "m17n-db",
"libm17n-flt", "libotf" to correctly display such complex scripts as
Indic and Khmer, and also for scripts that require Arabic shaping
support (Arabic and Farsi).  On some systems, particularly GNU/Linux,
these libraries may be already present or available as additional
packages.  Note that if there is a separate 'dev' or 'devel' package,
for use at compilation time rather than run time, you will need that
as well as the corresponding run time package; typically the dev
package will contain header files and a library archive.  Otherwise,
you can download the libraries from <https://www.nongnu.org/m17n/>.

Note that Emacs cannot support complex scripts on a TTY, unless the
terminal includes such a support.

* intlfonts-VERSION.tar.gz

The intlfonts distribution contains X11 fonts in various encodings
that Emacs can use to display international characters.  If you see a
non-ASCII character appear as a hollow box, that means you don't have
a font for it.  You might find one in the intlfonts distribution.  If
you do have a font for a non-ASCII character, but some characters
don't look right, or appear improperly aligned, a font from the
intlfonts distribution might look better.

The fonts in the intlfonts distribution are also used by the ps-print
package for printing international characters.  The file
lisp/ps-mule.el defines the *.bdf font files required for printing
each character set.

The intlfonts distribution contains its own installation instructions,
in the intlfonts/README file.

* Image support libraries

Emacs needs libraries to display images, with the exception of PBM and
XBM images whose support is built-in.

On some systems, particularly on GNU/Linux, these libraries may
already be present or available as additional packages.  If
there is a separate 'dev' or 'devel' package, for use at compilation
time rather than run time, you will need that as well as the
corresponding run time package; typically the dev package will
contain header files and a library archive.  Otherwise, you can
download and build libraries from sources.  Although none of them are
essential for running Emacs, some are important enough that
'configure' will report an error if they are absent from a system that
has X11 support, unless 'configure' is specifically told to omit them.

Here's a list of some of these libraries, and the URLs where they
can be found (in the unlikely event that your distribution does not
provide them).  By default, libraries marked with an X are required if
X11 is being used.

    libXaw3d          https://directory.fsf.org/project/Xaw3d
  X libxpm for XPM:   https://www.x.org/releases/current/src/lib/
  X libpng for PNG:   http://www.libpng.org/
    libz (for PNG):   https://www.zlib.net/
  X libjpeg for JPEG: https://www.ijg.org/
  X libtiff for TIFF: http://www.simplesystems.org/libtiff/
  X libgif for GIF:   http://giflib.sourceforge.net/
    librsvg2 for SVG: https://wiki.gnome.org/Projects/LibRsvg

If you supply the appropriate --without-LIB option, 'configure' will
omit the corresponding library from Emacs, even if that makes for a
less-pleasant user interface.  Otherwise, Emacs will configure itself
to build with these libraries if 'configure' finds them on your
system, and 'configure' will complain and exit if a library marked 'X'
is not found on a system that uses X11.  Use --without-LIB if your
version of a library won't work because some routines are missing.

* Extra fonts

The Emacs distribution does not include fonts and does not install
them.

On the GNU system, Emacs supports both X fonts and local fonts
(i.e. fonts managed by the fontconfig library).  If you need more
fonts than your distribution normally provides, you must install them
yourself.  See <https://www.gnu.org/software/freefont/> for a large
number of free Unicode fonts.

* GNU/Linux development packages

Many GNU/Linux systems do not come with development packages by default;
they include the files that you need to run Emacs, but not those you
need to compile it.  For example, to compile Emacs with support for X
and graphics libraries, you may need to install the X development
package(s), and development versions of the jpeg, png, etc. packages.

The names of the packages that you need vary according to the
GNU/Linux distribution that you use, and the options that you want to
configure Emacs with.  On Debian-based systems, you can install all the
packages needed to build the installed version of Emacs with a command
like 'apt-get build-dep emacs' (on older systems, replace 'emacs' with
eg 'emacs25').  On Red Hat-based systems, the corresponding command is
'dnf builddep emacs' (on older systems, use 'yum-builddep' instead).


DETAILED BUILDING AND INSTALLATION:

(This is for a Unix or Unix-like system.  For GNUstep and macOS,
see nextstep/INSTALL.  For non-ancient versions of MS Windows, see
the file nt/INSTALL.  For MS-DOS and MS Windows 3.X, see msdos/INSTALL.)

1) See BASIC INSTALLATION above for getting and configuring Emacs.

2) In the unlikely event that 'configure' does not detect your system
type correctly, consult './etc/MACHINES' to see what --host, --build
options you should pass to 'configure'.  That file also offers hints
for getting around some possible installation problems.

3) You can build Emacs in the top-level Emacs source directory
or in a separate directory.

3a) To build in the top-level Emacs source directory, go to that
directory and run the program 'configure' as follows:

    ./configure [--OPTION[=VALUE]] ...

If 'configure' cannot determine your system type, try again
specifying the proper --build, --host options explicitly.

If you don't want X support, specify '--with-x=no'.  If you omit this
option, 'configure' will try to figure out for itself whether your
system has X, and arrange to use it if present.

The '--x-includes=DIR' and '--x-libraries=DIR' options tell the build
process where the compiler should look for the include files and
object libraries used with the X Window System.  Normally, 'configure'
is able to find them; these options are necessary if you have your X
Window System files installed in unusual places.  These options also
accept a list of directories, separated with colons.

To get more attractive menus, you can specify an X toolkit when you
configure Emacs; use the option '--with-x-toolkit=TOOLKIT', where
TOOLKIT is 'gtk' (the default), 'athena', or 'motif' ('yes' and
'lucid' are synonyms for 'athena').  Compiling with Motif causes a
standard File Selection Dialog to pop up when you invoke file commands
with the mouse.  You can get fancy 3D-style scroll bars, even without
Gtk or Motif, if you have the Xaw3d library installed (see
"Image support libraries" above for Xaw3d availability).

You can tell configure where to search for GTK by giving it the
argument PKG_CONFIG='/full/name/of/pkg-config'.

Emacs will autolaunch a D-Bus session bus, when the environment
variable DISPLAY is set, but no session bus is running.  This might be
inconvenient for Emacs when running as daemon or running via a remote
ssh connection.  In order to completely prevent the use of D-Bus, configure
Emacs with the options '--without-dbus --without-gconf --without-gsettings'.

To read email via a network protocol like IMAP or POP, you can
configure Emacs with the option '--with-mailutils', so that it always
uses the GNU Mailutils 'movemail' program to retrieve mail; this is
the default if GNU Mailutils is installed.  Otherwise the Emacs build
procedure builds and installs an auxiliary 'movemail' program, a
limited and insecure substitute; when this happens, there are several
configure options such as --without-pop that provide fine-grained
control over Emacs 'movemail' construction.

The Emacs mail reader RMAIL is configured to be able to read mail from
a POP3 server by default.  Versions of the POP protocol older than
POP3 are not supported.  While POP3 support is typically enabled,
whether Emacs actually uses POP3 is controlled by individual users;
see the Rmail chapter of the Emacs manual.  Unless --with-mailutils is
in effect, it is a good idea to configure without POP3 support so that
users are less likely to inadvertently read email via insecure
channels.  On native MS-Windows, --with-pop is the default; on other
platforms, --without-pop is the default.

For image support you may have to download, build, and install the
appropriate image support libraries for image types other than XBM and
PBM, see the list of URLs in "Image support libraries" above.
(Note that PNG support requires libz in addition to libpng.)

To disable individual types of image support in Emacs for some reason,
even though configure finds the libraries, you can configure with one
or more of these options:

  --without-xpm          for XPM image support
  --without-jpeg         for JPEG image support
  --without-tiff         for TIFF image support
  --without-gif          for GIF image support
  --without-png          for PNG image support
  --without-rsvg         for SVG image support

Although ImageMagick support is disabled by default due to security
and stability concerns, you can enable it with --with-imagemagick.

Use --without-toolkit-scroll-bars to disable Motif or Xaw3d scroll bars.

Use --without-xim to inhibit the default use of X Input Methods.
In this case, the X resource useXIM can be used to turn on use of XIM.

Use --disable-largefile to omit support for files larger than 2GB on
systems which support that.

Use --without-sound to disable sound support.

Use --without-all for a smaller executable with fewer dependencies on
external libraries, at the cost of disabling many features.  Although
--without-all disables libraries not needed for ordinary Emacs
operation, it does enable X support, and using the GTK2 or GTK3
toolkit creates a lot of library dependencies.  So if you want to
build a small executable with very basic X support, use --without-all
--with-x-toolkit=no.  For the smallest possible executable without X,
use --without-all --without-x.  If you want to build with just a few
features enabled, you can combine --without-all with --with-FEATURE.
For example, you can use --without-all --without-x --with-dbus to
build with D-Bus support and nothing more.

Use --with-gnutls=ifavailable to use GnuTLS if available but go ahead
and build without it if not available.  This overrides Emacs's default
behavior of refusing to build if GnuTLS is absent.  When X11 support
is enabled, the libraries for gif, jpeg, png, tiff, and xpm are in the
same strongly-recommended category as GnuTLS, and have similar options.

Use --with-wide-int to implement Emacs values with the type 'long long',
even on hosts where a narrower type would do.  With this option, on a
typical 32-bit host, Emacs integers have 62 bits instead of 30.

Use --with-cairo to compile Emacs with Cairo drawing.

Use --with-modules to build Emacs with support for dynamic modules.
This needs a C compiler that supports '__attribute__ ((cleanup (...)))',
as in GCC 3.4 and later.

Use --enable-gcc-warnings to enable compile-time checks that warn
about possibly-questionable C code.  This is intended for developers
and is useful with GNU-compatible compilers.  On a recent GNU system
there should be no warnings; on older and on non-GNU systems the
generated warnings may still be useful, though you may prefer
configuring with --enable-gcc-warnings=warn-only so they are not
treated as errors.  The default is --enable-gcc-warnings=warn-only if
it appears to be a developer build, and is --disable-gcc-warnings
otherwise.

Use --disable-silent-rules to cause 'make' to give more details about
the commands it executes.  This can be helpful when debugging a build
that goes awry.  'make V=1' also enables the extra chatter.

Use --enable-link-time-optimization to enable link-time optimization.
With GCC, you need GCC 4.5.0 and later, and 'configure' arranges for
linking to be parallelized if possible.  With Clang, you need GNU
binutils with the gold linker and plugin support, along with the LLVM
gold plugin <https://llvm.org/docs/GoldPlugin.html>.  Link time
optimization is not the default as it tends to cause crashes and to
make Emacs slower.

The '--prefix=PREFIXDIR' option specifies where the installation process
should put emacs and its data files.  This defaults to '/usr/local'.
- Emacs (and the other utilities users run) go in PREFIXDIR/bin
  (unless the '--exec-prefix' option says otherwise).
- The architecture-independent files go in PREFIXDIR/share/emacs/VERSION
  (where VERSION is the version number of Emacs, like '23.2').
- The architecture-dependent files go in
  PREFIXDIR/libexec/emacs/VERSION/CONFIGURATION
  (where CONFIGURATION is the configuration name, like
  i686-pc-linux-gnu), unless the '--exec-prefix' option says otherwise.

The '--exec-prefix=EXECDIR' option allows you to specify a separate
portion of the directory tree for installing architecture-specific
files, like executables and utility programs.  If specified,
- Emacs (and the other utilities users run) go in EXECDIR/bin, and
- The architecture-dependent files go in
  EXECDIR/libexec/emacs/VERSION/CONFIGURATION.
EXECDIR/bin should be a directory that is normally in users' PATHs.

For example, the command

    ./configure --build=i386-linux-gnu --without-sound

configures Emacs to build for a 32-bit GNU/Linux distribution,
without sound support.

'configure' doesn't do any compilation or installation itself.
It just creates the files that influence those things:
'./Makefile' in the top-level directory and several subdirectories;
and './src/config.h'.

When it is done, 'configure' prints a description of what it did and
creates a shell script 'config.status' which, when run, recreates the
same configuration.  If 'configure' exits with an error after
disturbing the status quo, it removes 'config.status'.  'configure'
also creates a file 'config.cache' that saves the results of its tests
to make reconfiguring faster, and a file 'config.log' containing compiler
output (useful mainly for debugging 'configure').  You can give
'configure' the option '--cache-file=FILE' to use the results of the
tests in FILE instead of 'config.cache'.  Set FILE to '/dev/null' to
disable caching, for debugging 'configure'.

If the description of the system configuration printed by 'configure'
is not right, or if it claims some of the features or libraries are not
available when you know they are, look at the 'config.log' file for
the trace of the failed tests performed by 'configure' to check
whether these features are supported.  Typically, some test fails
because the compiler cannot find some function in the system
libraries, or some macro-processor definition in the system headers.

Some tests might fail because the compiler should look in special
directories for some header files, or link against optional
libraries, or use special compilation options.  You can force
'configure' and the build process which follows it to do that by
setting the variables CPPFLAGS, CFLAGS, LDFLAGS, LIBS, CPP and CC
before running 'configure'.  CPP is the command which invokes the
preprocessor, CPPFLAGS lists the options passed to it, CFLAGS are
compilation options, LDFLAGS are options used when linking, LIBS are
libraries to link against, and CC is the command which invokes the
compiler.  By default, gcc is used if available.

Here's an example of a 'configure' invocation, assuming a Bourne-like
shell such as Bash, which uses these variables:

  ./configure \
    CPPFLAGS='-I/foo/myinclude' LDFLAGS='-L/bar/mylib' \
    CFLAGS='-O3' LIBS='-lfoo -lbar'

(this is all one shell command).  This tells 'configure' to instruct the
preprocessor to look in the '/foo/myinclude' directory for header
files (in addition to the standard directories), instruct the linker
to look in '/bar/mylib' for libraries, pass the -O3 optimization
switch to the compiler, and link against libfoo and libbar
libraries in addition to the standard ones.

For some libraries, like Gtk+, fontconfig and ALSA, 'configure' uses
pkg-config to find where those libraries are installed.
If you want pkg-config to look in special directories, you have to set
PKG_CONFIG_PATH to point to the directories where the .pc-files for
those libraries are.  For example:

  ./configure \
    PKG_CONFIG_PATH='/usr/local/alsa/lib/pkgconfig:/opt/gtk+-2.8/lib/pkgconfig'

3b) To build in a separate directory, go to that directory
and run the program 'configure' as follows:

    SOURCE-DIR/configure CONFIGURATION-NAME [--OPTION[=VALUE]] ...

SOURCE-DIR refers to the top-level Emacs source directory which is
where Emacs's configure script is located.  'configure' looks for the
Emacs source code in the directory that 'configure' is in.

4) Put into './lisp/site-init.el' or './lisp/site-load.el' any Emacs
Lisp code you want Emacs to load before it is dumped out.  Use
site-load.el for additional libraries if you arrange for their
documentation strings to be in the etc/DOC file (see
src/Makefile.in if you wish to figure out how to do that).  For all
else, use site-init.el.  Do not load byte-compiled code which
was built with a non-nil value of 'byte-compile-dynamic'.

It is not a good idea to edit the normal .el files that come with Emacs.
Instead, use a file like site-init.el to change settings.

To change the value of a variable that is already defined in Emacs,
you should use the Lisp function 'setq', not 'defvar'.  For example,

     (setq news-inews-program "/usr/bin/inews")

is how you would override the default value of the variable
news-inews-program.

Before you override a variable this way, *look at the value* that the
variable gets by default!  Make sure you know what kind of value the
variable should have.  If you don't pay attention to what you are
doing, you'll make a mistake.

The 'site-*.el' files are nonexistent in the distribution.  You do not
need to create them if you have nothing to put in them.

5) Refer to the file './etc/TERMS' for information on fields you may
wish to add to various termcap entries.  (This is unlikely to be necessary.)

6) Run 'make' in the top directory of the Emacs distribution to finish
building Emacs in the standard way.  The final executable file is
named 'src/emacs'.  You can execute this file "in place" without
copying it, if you wish; then it automatically uses the sibling
directories ../lisp, ../lib-src, ../info.

Or you can "install" the executable and the other files into their
installed locations, with 'make install'.  By default, Emacs's files
are installed in the following directories:

'/usr/local/bin' holds the executable programs users normally run -
                'emacs', 'etags', 'ctags', 'emacsclient'.

'/usr/local/share/emacs/VERSION/lisp' holds the Emacs Lisp library;
                'VERSION' stands for the number of the Emacs version
                you are installing, like '23.1' or '23.2'.  Since the
                Lisp library changes from one version of Emacs to
                another, including the version number in the path
                allows you to have several versions of Emacs installed
                at the same time; in particular, you don't have to
                make Emacs unavailable while installing a new version.

'/usr/local/share/emacs/VERSION/etc' holds the Emacs tutorial, the DOC
                file, and other architecture-independent files Emacs
                might need while running.

'/usr/local/libexec/emacs/VERSION/CONFIGURATION-NAME' contains executable
                programs used by Emacs that users are not expected to
                run themselves.
                'VERSION' is the number of the Emacs version you are
                installing, and 'CONFIGURATION-NAME' is the value
                deduced by the 'configure' program to identify the
                architecture and operating system of your machine,
                like 'i686-pc-linux-gnu' or 'sparc-sun-sunos'.  Since
                these files are specific to the version of Emacs,
                operating system, and architecture in use, including
                the configuration name in the path allows you to have
                several versions of Emacs for any mix of machines and
                operating systems installed at the same time; this is
                useful for sites at which different kinds of machines
                share the file system Emacs is installed on.

'/usr/local/share/info' holds the on-line documentation for Emacs,
                known as "info files".  Many other GNU programs are
                documented using info files as well, so this directory
                stands apart from the other, Emacs-specific directories.

'/usr/local/share/man/man1' holds the man pages for the programs installed
                in '/usr/local/bin'.

Any version of Emacs, whether installed or not, also looks for Lisp
files in these directories.

'/usr/local/share/emacs/VERSION/site-lisp' holds the local Emacs Lisp
                files installed for Emacs version VERSION only.

'/usr/local/share/emacs/site-lisp' holds the local Emacs Lisp
                files installed for all Emacs versions.

                When Emacs is installed, it searches for its Lisp files
                in '/usr/local/share/emacs/VERSION/site-lisp', then in
                '/usr/local/share/emacs/site-lisp', and finally in
                '/usr/local/share/emacs/VERSION/lisp'.

If these directories are not what you want, you can specify where to
install Emacs's libraries and data files or where Emacs should search
for its Lisp files by giving values for 'make' variables as part of
the command.  See the section below called 'MAKE VARIABLES' for more
information on this.

7) Check the file 'dir' in your site's info directory (usually
/usr/local/share/info) to make sure that it has a menu entry for the
Emacs info files.

8) If your system uses lock files to interlock access to mailer inbox files,
and if --with-mailutils is not in effect, then you might need to
make the Emacs-specific 'movemail' program setuid or setgid in order
to enable it to write the lock files.  We believe this is safe.

9) You are done!  You can remove executables and object files from
the build directory by typing 'make clean'.  To also remove the files
that 'configure' created (so you can compile Emacs for a different
configuration), type 'make distclean'.


MAKE VARIABLES

You can change where the build process installs Emacs and its data
files by specifying values for 'make' variables as part of the 'make'
command line.  For example, if you type

    make install bindir=/usr/local/gnubin

the 'bindir=/usr/local/gnubin' argument indicates that the Emacs
executable files should go in '/usr/local/gnubin', not
'/usr/local/bin'.

Here is a complete list of the variables you may want to set.

'bindir' indicates where to put executable programs that users can
        run.  This defaults to /usr/local/bin.

'datadir' indicates where to put the architecture-independent
        read-only data files that Emacs refers to while it runs; it
        defaults to /usr/local/share.  We create the following
        subdirectories under 'datadir':
        - 'emacs/VERSION/lisp', containing the Emacs Lisp library, and
        - 'emacs/VERSION/etc', containing the tutorials, DOC file, etc.
        'VERSION' is the number of the Emacs version you are installing,
        like '23.1' or '23.2'.  Since these files vary from one version
        of Emacs to another, including the version number in the path
        allows you to have several versions of Emacs installed at the
        same time; this means that you don't have to make Emacs
        unavailable while installing a new version.

'libexecdir' indicates where to put architecture-specific data files that
        Emacs refers to as it runs; it defaults to '/usr/local/libexec'.
        We create the following subdirectories under 'libexecdir':
        - 'emacs/VERSION/CONFIGURATION-NAME', containing executable
                programs used by Emacs that users are not expected to run
                themselves.
        'VERSION' is the number of the Emacs version you are installing,
        and 'CONFIGURATION-NAME' is the value deduced by the
        'configure' program to identify the architecture and operating
        system of your machine, like 'i686-pc-linux-gnu' or 'sparc-sun-sunos'.
        Since these files are specific to the version of Emacs,
        operating system, and architecture in use, including the
        configuration name in the path allows you to have several
        versions of Emacs for any mix of machines and operating
        systems installed at the same time; this is useful for sites
        at which different kinds of machines share the file system
        Emacs is installed on.

'infodir' indicates where to put the info files distributed with
        Emacs; it defaults to '/usr/local/share/info'.

'mandir' indicates where to put the man pages for Emacs and its
        utilities (like 'etags'); it defaults to
        '/usr/local/share/man/man1'.

'prefix' doesn't give a path for any specific part of Emacs; instead,
        its value is used to determine the defaults for all the
        architecture-independent path variables - 'datadir',
        'sharedstatedir', 'infodir', and 'mandir'.  Its default value is
        '/usr/local'; the other variables add on 'lib' or 'man' to it
        by default.

        For example, suppose your site generally places GNU software
        under '/usr/users/software/gnusoft' instead of '/usr/local'.
        By including
            'prefix=/usr/users/software/gnusoft'
        in the arguments to 'make', you can instruct the build process
        to place all of the Emacs data files in the appropriate
        directories under that path.

'exec_prefix' serves the same purpose as 'prefix', but instead
        determines the default values for the architecture-dependent
        path variables - 'bindir' and 'libexecdir'.

The above variables serve analogous purposes in the makefiles for all
GNU software; the following variables are specific to Emacs.

'archlibdir' indicates where Emacs installs and expects the executable
        files and other architecture-dependent data it uses while
        running.  Its default value, based on 'libexecdir' (which
        see), is '/usr/local/libexec/emacs/VERSION/CONFIGURATION-NAME'
        (where VERSION and CONFIGURATION-NAME are as described above).

'GZIP_PROG' is the name of the executable that compresses installed info,
        manual, and .el files.  It defaults to gzip.  Setting it to
        the empty string suppresses compression.

Remember that you must specify any variable values you need each time
you run 'make' in the top directory.  If you run 'make' once to build
emacs, test it, and then run 'make' again to install the files, you
must provide the same variable settings each time.  To make the
settings persist, you can edit them into the 'Makefile' in the top
directory, but be aware that running the 'configure' program erases
'Makefile' and rebuilds it from 'Makefile.in'.

The path for finding Lisp files is specified in src/epaths.h,
a file which is generated by running configure.  To change the path,
you can edit the definition of PATH_LOADSEARCH in that file
before you run 'make'.

The top-level Makefile stores the variable settings it used in the
Makefiles for the subdirectories, so you don't have to specify them
when running make in the subdirectories.


PROBLEMS

See the file './etc/PROBLEMS' for a list of various problems sometimes
encountered, and what to do about them.
\f
This file is part of GNU Emacs.

GNU Emacs is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.