Subversion Repositories scarts

@comment This file is included by both standards.texi and make.texinfo.

@comment It was broken out of standards.texi on 1/6/93 by roland.

@node Makefile Conventions

@chapter Makefile Conventions

@comment standards.texi does not print an index, but make.texinfo does.

@cindex makefile, conventions for

@cindex conventions for makefiles

@cindex standards for makefiles

@c Copyright (C) 1992, 1993, 1994, 1995, 1996, 1997, 1998, 2000, 2001,

@c 2004, 2005, 2006 Free Software Foundation, Inc.

@c Permission is granted to copy, distribute and/or modify this document

@c under the terms of the GNU Free Documentation License, Version 1.2

@c or any later version published by the Free Software Foundation;

@c with no Invariant Sections, with no

@c Front-Cover Texts, and with no Back-Cover Texts.

@c A copy of the license is included in the section entitled ``GNU

@c Free Documentation License''.

This

@ifinfo

node

@end ifinfo

@iftex

@ifset CODESTD

section

@end ifset

@ifclear CODESTD

chapter

@end ifclear

@end iftex

describes conventions for writing the Makefiles for GNU programs.

Using Automake will help you write a Makefile that follows these

conventions.

@menu

* Makefile Basics::             General conventions for Makefiles.

* Utilities in Makefiles::      Utilities to be used in Makefiles.

* Command Variables::           Variables for specifying commands.

* DESTDIR::                     Supporting staged installs.

* Directory Variables::         Variables for installation directories.

* Standard Targets::            Standard targets for users.

* Install Command Categories::  Three categories of commands in the `install'

                                  rule: normal, pre-install and post-install.

@end menu

@node Makefile Basics

@section General Conventions for Makefiles

Every Makefile should contain this line:

@example

SHELL = /bin/sh

@end example

@noindent

to avoid trouble on systems where the @code{SHELL} variable might be

inherited from the environment.  (This is never a problem with GNU

@code{make}.)

Different @code{make} programs have incompatible suffix lists and

implicit rules, and this sometimes creates confusion or misbehavior.  So

it is a good idea to set the suffix list explicitly using only the

suffixes you need in the particular Makefile, like this:

@example

.SUFFIXES:

.SUFFIXES: .c .o

@end example

@noindent

The first line clears out the suffix list, the second introduces all

suffixes which may be subject to implicit rules in this Makefile.

Don't assume that @file{.} is in the path for command execution.  When

you need to run programs that are a part of your package during the

make, please make sure that it uses @file{./} if the program is built as

part of the make or @file{$(srcdir)/} if the file is an unchanging part

of the source code.  Without one of these prefixes, the current search

path is used.

The distinction between @file{./} (the @dfn{build directory}) and

@file{$(srcdir)/} (the @dfn{source directory}) is important because

users can build in a separate directory using the @samp{--srcdir} option

to @file{configure}.  A rule of the form:

@smallexample

foo.1 : foo.man sedscript

        sed -e sedscript foo.man > foo.1

@end smallexample

@noindent

will fail when the build directory is not the source directory, because

@file{foo.man} and @file{sedscript} are in the source directory.

When using GNU @code{make}, relying on @samp{VPATH} to find the source

file will work in the case where there is a single dependency file,

since the @code{make} automatic variable @samp{$<} will represent the

source file wherever it is.  (Many versions of @code{make} set @samp{$<}

only in implicit rules.)  A Makefile target like

@smallexample

foo.o : bar.c

        $(CC) -I. -I$(srcdir) $(CFLAGS) -c bar.c -o foo.o

@end smallexample

@noindent

should instead be written as

@smallexample

foo.o : bar.c

        $(CC) -I. -I$(srcdir) $(CFLAGS) -c $< -o $@@

@end smallexample

@noindent

in order to allow @samp{VPATH} to work correctly.  When the target has

multiple dependencies, using an explicit @samp{$(srcdir)} is the easiest

way to make the rule work well.  For example, the target above for

@file{foo.1} is best written as:

@smallexample

foo.1 : foo.man sedscript

        sed -e $(srcdir)/sedscript $(srcdir)/foo.man > $@@

@end smallexample

GNU distributions usually contain some files which are not source

files---for example, Info files, and the output from Autoconf, Automake,

Bison or Flex.  Since these files normally appear in the source

directory, they should always appear in the source directory, not in the

build directory.  So Makefile rules to update them should put the

updated files in the source directory.

However, if a file does not appear in the distribution, then the

Makefile should not put it in the source directory, because building a

program in ordinary circumstances should not modify the source directory

in any way.

Try to make the build and installation targets, at least (and all their

subtargets) work correctly with a parallel @code{make}.

@node Utilities in Makefiles

@section Utilities in Makefiles

Write the Makefile commands (and any shell scripts, such as

@code{configure}) to run in @code{sh}, not in @code{csh}.  Don't use any

special features of @code{ksh} or @code{bash}.

The @code{configure} script and the Makefile rules for building and

installation should not use any utilities directly except these:

@c dd find

@c gunzip gzip md5sum

@c mkfifo mknod tee uname

@example

cat cmp cp diff echo egrep expr false grep install-info

ln ls mkdir mv pwd rm rmdir sed sleep sort tar test touch true

@end example

The compression program @code{gzip} can be used in the @code{dist} rule.

Stick to the generally supported options for these programs.  For

example, don't use @samp{mkdir -p}, convenient as it may be, because

most systems don't support it.

It is a good idea to avoid creating symbolic links in makefiles, since a

few systems don't support them.

The Makefile rules for building and installation can also use compilers

and related programs, but should do so via @code{make} variables so that the

user can substitute alternatives.  Here are some of the programs we

mean:

@example

ar bison cc flex install ld ldconfig lex

make makeinfo ranlib texi2dvi yacc

@end example

Use the following @code{make} variables to run those programs:

@example

$(AR) $(BISON) $(CC) $(FLEX) $(INSTALL) $(LD) $(LDCONFIG) $(LEX)

$(MAKE) $(MAKEINFO) $(RANLIB) $(TEXI2DVI) $(YACC)

@end example

When you use @code{ranlib} or @code{ldconfig}, you should make sure

nothing bad happens if the system does not have the program in question.

Arrange to ignore an error from that command, and print a message before

the command to tell the user that failure of this command does not mean

a problem.  (The Autoconf @samp{AC_PROG_RANLIB} macro can help with

this.)

If you use symbolic links, you should implement a fallback for systems

that don't have symbolic links.

Additional utilities that can be used via Make variables are:

@example

chgrp chmod chown mknod

@end example

It is ok to use other utilities in Makefile portions (or scripts)

intended only for particular systems where you know those utilities

exist.

@node Command Variables

@section Variables for Specifying Commands

Makefiles should provide variables for overriding certain commands, options,

and so on.

In particular, you should run most utility programs via variables.

Thus, if you use Bison, have a variable named @code{BISON} whose default

value is set with @samp{BISON = bison}, and refer to it with

@code{$(BISON)} whenever you need to use Bison.

File management utilities such as @code{ln}, @code{rm}, @code{mv}, and

so on, need not be referred to through variables in this way, since users

don't need to replace them with other programs.

Each program-name variable should come with an options variable that is

used to supply options to the program.  Append @samp{FLAGS} to the

program-name variable name to get the options variable name---for

example, @code{BISONFLAGS}.  (The names @code{CFLAGS} for the C

compiler, @code{YFLAGS} for yacc, and @code{LFLAGS} for lex, are

exceptions to this rule, but we keep them because they are standard.)

Use @code{CPPFLAGS} in any compilation command that runs the

preprocessor, and use @code{LDFLAGS} in any compilation command that

does linking as well as in any direct use of @code{ld}.

If there are C compiler options that @emph{must} be used for proper

compilation of certain files, do not include them in @code{CFLAGS}.

Users expect to be able to specify @code{CFLAGS} freely themselves.

Instead, arrange to pass the necessary options to the C compiler

independently of @code{CFLAGS}, by writing them explicitly in the

compilation commands or by defining an implicit rule, like this:

@smallexample

CFLAGS = -g

ALL_CFLAGS = -I. $(CFLAGS)

.c.o:

        $(CC) -c $(CPPFLAGS) $(ALL_CFLAGS) $<

@end smallexample

Do include the @samp{-g} option in @code{CFLAGS}, because that is not

@emph{required} for proper compilation.  You can consider it a default

that is only recommended.  If the package is set up so that it is

compiled with GCC by default, then you might as well include @samp{-O}

in the default value of @code{CFLAGS} as well.

Put @code{CFLAGS} last in the compilation command, after other variables

containing compiler options, so the user can use @code{CFLAGS} to

override the others.

@code{CFLAGS} should be used in every invocation of the C compiler,

both those which do compilation and those which do linking.

Every Makefile should define the variable @code{INSTALL}, which is the

basic command for installing a file into the system.

Every Makefile should also define the variables @code{INSTALL_PROGRAM}

and @code{INSTALL_DATA}.  (The default for @code{INSTALL_PROGRAM} should

be @code{$(INSTALL)}; the default for @code{INSTALL_DATA} should be

@code{$@{INSTALL@} -m 644}.)  Then it should use those variables as the

commands for actual installation, for executables and non-executables

respectively.  Minimal use of these variables is as follows:

@example

$(INSTALL_PROGRAM) foo $(bindir)/foo

$(INSTALL_DATA) libfoo.a $(libdir)/libfoo.a

@end example

However, it is preferable to support a @code{DESTDIR} prefix on the

target files, as explained in the next section.

@noindent

Always use a file name, not a directory name, as the second argument of

the installation commands.  Use a separate command for each file to be

installed.

@node DESTDIR

@section @code{DESTDIR}: support for staged installs

@vindex DESTDIR

@cindex staged installs

@cindex installations, staged

@code{DESTDIR} is a variable prepended to each installed target file,

like this:

@example

$(INSTALL_PROGRAM) foo $(DESTDIR)$(bindir)/foo

$(INSTALL_DATA) libfoo.a $(DESTDIR)$(libdir)/libfoo.a

@end example

The @code{DESTDIR} variable is specified by the user on the @code{make}

command line.  For example:

@example

make DESTDIR=/tmp/stage install

@end example

@noindent

@code{DESTDIR} should be supported only in the @code{install*} and

@code{uninstall*} targets, as those are the only targets where it is

useful.

If your installation step would normally install

@file{/usr/local/bin/foo} and @file{/usr/local/lib/libfoo.a}, then an

installation invoked as in the example above would install

@file{/tmp/stage/usr/local/bin/foo} and

@file{/tmp/stage/usr/local/lib/libfoo.a} instead.

Prepending the variable @code{DESTDIR} to each target in this way

provides for @dfn{staged installs}, where the installed files are not

placed directly into their expected location but are instead copied

into a temporary location (@code{DESTDIR}).  However, installed files

maintain their relative directory structure and any embedded file names

will not be modified.

You should not set the value of @code{DESTDIR} in your @file{Makefile}

at all; then the files are installed into their expected locations by

default.  Also, specifying @code{DESTDIR} should not change the

operation of the software in any way, so its value should not be

included in any file contents.

@code{DESTDIR} support is commonly used in package creation.  It is

also helpful to users who want to understand what a given package will

install where, and to allow users who don't normally have permissions

to install into protected areas to build and install before gaining

those permissions.  Finally, it can be useful with tools such as

@code{stow}, where code is installed in one place but made to appear

to be installed somewhere else using symbolic links or special mount

operations.  So, we strongly recommend GNU packages support

@code{DESTDIR}, though it is not an absolute requirement.

@node Directory Variables

@section 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

@command{make} (e.g., @kbd{make prefix=/usr install} or

@command{configure} (e.g., @kbd{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.

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.

@table @code

@item prefix

@vindex prefix

A prefix used in constructing the default values of the variables listed

below.  The default value of @code{prefix} should be @file{/usr/local}.

When building the complete GNU system, the prefix will be empty and

@file{/usr} will be a symbolic link to @file{/}.

(If you are using Autoconf, write it as @samp{@@prefix@@}.)

Running @samp{make install} with a different value of @code{prefix} from

the one used to build the program should @emph{not} recompile the

program.

@item exec_prefix

@vindex exec_prefix

A prefix used in constructing the default values of some of the

variables listed below.  The default value of @code{exec_prefix} should

be @code{$(prefix)}.

(If you are using Autoconf, write it as @samp{@@exec_prefix@@}.)

Generally, @code{$(exec_prefix)} is used for directories that contain

machine-specific files (such as executables and subroutine libraries),

while @code{$(prefix)} is used directly for other directories.

Running @samp{make install} with a different value of @code{exec_prefix}

from the one used to build the program should @emph{not} recompile the

program.

@end table

Executable programs are installed in one of the following directories.

@table @code

@item bindir

@vindex bindir

The directory for installing executable programs that users can run.

This should normally be @file{/usr/local/bin}, but write it as

@file{$(exec_prefix)/bin}.

(If you are using Autoconf, write it as @samp{@@bindir@@}.)

@item sbindir

@vindex 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 @file{/usr/local/sbin}, but write it as

@file{$(exec_prefix)/sbin}.

(If you are using Autoconf, write it as @samp{@@sbindir@@}.)

@item libexecdir

@vindex libexecdir

@comment This paragraph adjusted to avoid overfull hbox --roland 5jul94

The directory for installing executable programs to be run by other

programs rather than by users.  This directory should normally be

@file{/usr/local/libexec}, but write it as @file{$(exec_prefix)/libexec}.

(If you are using Autoconf, write it as @samp{@@libexecdir@@}.)

The definition of @samp{libexecdir} is the same for all packages, so

you should install your data in a subdirectory thereof.  Most packages

install their data under @file{$(libexecdir)/@var{package-name}/},

possibly within additional subdirectories thereof, such as

@file{$(libexecdir)/@var{package-name}/@var{machine}/@var{version}}.

@end table

Data files used by the program during its execution are divided into

categories in two ways.

@itemize @bullet

@item

Some files are normally modified by programs; others are never normally

modified (though users may edit some of these).

@item

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.

@end itemize

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:

@table @samp

@item datarootdir

The root of the directory tree for read-only architecture-independent

data files.  This should normally be @file{/usr/local/share}, but

write it as @file{$(prefix)/share}.  (If you are using Autoconf, write

it as @samp{@@datarootdir@@}.)  @samp{datadir}'s default value is

based on this variable; so are @samp{infodir}, @samp{mandir}, and

others.

@item datadir

The directory for installing idiosyncratic read-only

architecture-independent data files for this program.  This is usually

the same place as @samp{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 @file{/usr/local/share}, but write it as

@file{$(datarootdir)}.  (If you are using Autoconf, write it as

@samp{@@datadir@@}.)

The definition of @samp{datadir} is the same for all packages, so you

should install your data in a subdirectory thereof.  Most packages

install their data under @file{$(datadir)/@var{package-name}/}.

@item 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, @file{/etc/passwd}, and so forth belong

here.  All the files in this directory should be ordinary ASCII text

files.  This directory should normally be @file{/usr/local/etc}, but

write it as @file{$(prefix)/etc}.

(If you are using Autoconf, write it as @samp{@@sysconfdir@@}.)

Do not install executables here in this directory (they probably belong

in @file{$(libexecdir)} or @file{$(sbindir)}).  Also do not install

files that are modified in the normal course of their use (programs

whose purpose is to change the configuration of the system excluded).

Those probably belong in @file{$(localstatedir)}.

@item sharedstatedir

The directory for installing architecture-independent data files which

the programs modify while they run.  This should normally be

@file{/usr/local/com}, but write it as @file{$(prefix)/com}.

(If you are using Autoconf, write it as @samp{@@sharedstatedir@@}.)

@item 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 @file{$(datadir)} or @file{$(sysconfdir)}.  @file{$(localstatedir)}

should normally be @file{/usr/local/var}, but write it as

@file{$(prefix)/var}.

(If you are using Autoconf, write it as @samp{@@localstatedir@@}.)

@end table

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 @samp{infodir}, but not all

need @samp{libdir} or @samp{lispdir}.

@table @samp

@item includedir

@c rewritten to avoid overfull hbox --roland

The directory for installing header files to be included by user

programs with the C @samp{#include} preprocessor directive.  This

should normally be @file{/usr/local/include}, but write it as

@file{$(prefix)/include}.

(If you are using Autoconf, write it as @samp{@@includedir@@}.)

Most compilers other than GCC do not look for header files in directory

@file{/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 @code{includedir} and one

specified by @code{oldincludedir}.

@item oldincludedir

The directory for installing @samp{#include} header files for use with

compilers other than GCC.  This should normally be @file{/usr/include}.

(If you are using Autoconf, you can write it as @samp{@@oldincludedir@@}.)

The Makefile commands should check whether the value of

@code{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 @file{foo.h}, then it should install the header

file in the @code{oldincludedir} directory if either (1) there is no

@file{foo.h} there or (2) the @file{foo.h} that exists came from the Foo

package.

To tell whether @file{foo.h} came from the Foo package, put a magic

string in the file---part of a comment---and @code{grep} for that string.

@item docdir

The directory for installing documentation files (other than Info) for

this package.  By default, it should be

@file{/usr/local/share/doc/@var{yourpkg}}, but it should be written as

@file{$(datarootdir)/doc/@var{yourpkg}}.  (If you are using Autoconf,

write it as @samp{@@docdir@@}.)  The @var{yourpkg} subdirectory, which

may include a version number, prevents collisions among files with

common names, such as @file{README}.

@item infodir

The directory for installing the Info files for this package.  By

default, it should be @file{/usr/local/share/info}, but it should be

written as @file{$(datarootdir)/info}.  (If you are using Autoconf,

write it as @samp{@@infodir@@}.)  @code{infodir} is separate from

@code{docdir} for compatibility with existing practice.

@item htmldir

@itemx dvidir

@itemx pdfdir

@itemx psdir

Directories for installing documentation files in the particular

format.  They should all be set to @code{$(docdir)} by default.  (If

you are using Autoconf, write them as @samp{@@htmldir@@},

@samp{@@dvidir@@}, etc.)  Packages which supply several translations

of their documentation should install them in

@samp{$(htmldir)/}@var{ll}, @samp{$(pdfdir)/}@var{ll}, etc. where

@var{ll} is a locale abbreviation such as @samp{en} or @samp{pt_BR}.

@item libdir

The directory for object files and libraries of object code.  Do not

install executables here, they probably ought to go in @file{$(libexecdir)}

instead.  The value of @code{libdir} should normally be

@file{/usr/local/lib}, but write it as @file{$(exec_prefix)/lib}.

(If you are using Autoconf, write it as @samp{@@libdir@@}.)

@item lispdir

The directory for installing any Emacs Lisp files in this package.  By

default, it should be @file{/usr/local/share/emacs/site-lisp}, but it

should be written as @file{$(datarootdir)/emacs/site-lisp}.

If you are using Autoconf, write the default as @samp{@@lispdir@@}.

In order to make @samp{@@lispdir@@} work, you need the following lines

in your @file{configure.in} file:

@example

lispdir='$@{datarootdir@}/emacs/site-lisp'

AC_SUBST(lispdir)

@end example

@item localedir

The directory for installing locale-specific message catalogs for this

package.  By default, it should be @file{/usr/local/share/locale}, but

it should be written as @file{$(datarootdir)/locale}.  (If you are

using Autoconf, write it as @samp{@@localedir@@}.)  This directory

usually has a subdirectory per locale.

@end table

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

@table @samp

@item mandir

The top-level directory for installing the man pages (if any) for this

package.  It will normally be @file{/usr/local/share/man}, but you

should write it as @file{$(datarootdir)/man}.  (If you are using

Autoconf, write it as @samp{@@mandir@@}.)

@item man1dir

The directory for installing section 1 man pages.  Write it as

@file{$(mandir)/man1}.

@item man2dir

The directory for installing section 2 man pages.  Write it as

@file{$(mandir)/man2}

@item @dots{}

@strong{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.}

@item manext

The file name extension for the installed man page.  This should contain

a period followed by the appropriate digit; it should normally be @samp{.1}.

@item man1ext

The file name extension for installed section 1 man pages.

@item man2ext

The file name extension for installed section 2 man pages.

@item @dots{}

Use these names instead of @samp{manext} if the package needs to install man

pages in more than one section of the manual.

@end table

And finally, you should set the following variable:

@table @samp

@item srcdir

The directory for the sources being compiled.  The value of this

variable is normally inserted by the @code{configure} shell script.

(If you are using Autoconf, use @samp{srcdir = @@srcdir@@}.)

@end table

For example:

@smallexample

@c I have changed some of the comments here slightly to fix an overfull

@c hbox, so the make manual can format correctly. --roland

# 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

@end smallexample

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 @code{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@tie{}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.

@node Standard Targets

@section Standard Targets for Users

All GNU programs should have the following targets in their Makefiles:

@table @samp

@item all

Compile the entire program.  This should be the default target.  This

target need not rebuild any documentation files; Info files should

normally be included in the distribution, and DVI (and other

documentation format) files should be made only when explicitly asked

for.

By default, the Make rules should compile and link with @samp{-g}, so

that executable programs have debugging symbols.  Users who don't mind

being helpless can strip the executables later if they wish.

@item install

Compile the program and copy the executables, libraries, and so on to

the file names where they should reside for actual use.  If there is a

simple test to verify that a program is properly installed, this target

should run that test.

Do not strip executables when installing them.  Devil-may-care users can

use the @code{install-strip} target to do that.

If possible, write the @code{install} target rule so that it does not

modify anything in the directory where the program was built, provided

@samp{make all} has just been done.  This is convenient for building the

program under one user name and installing it under another.

The commands should create all the directories in which files are to be

installed, if they don't already exist.  This includes the directories

specified as the values of the variables @code{prefix} and

@code{exec_prefix}, as well as all subdirectories that are needed.

One way to do this is by means of an @code{installdirs} target

as described below.

Use @samp{-} before any command for installing a man page, so that

@code{make} will ignore any errors.  This is in case there are systems

that don't have the Unix man page documentation system installed.

The way to install Info files is to copy them into @file{$(infodir)}

with @code{$(INSTALL_DATA)} (@pxref{Command Variables}), and then run

the @code{install-info} program if it is present.  @code{install-info}

is a program that edits the Info @file{dir} file to add or update the

menu entry for the given Info file; it is part of the Texinfo package.

Here is a sample rule to install an Info file:

@comment This example has been carefully formatted for the Make manual.

@comment Please do not reformat it without talking to bug-make@gnu.org.

@smallexample

$(DESTDIR)$(infodir)/foo.info: foo.info

        $(POST_INSTALL)

# There may be a newer info file in . than in srcdir.

        -if test -f foo.info; then d=.; \

         else d=$(srcdir); fi; \

        $(INSTALL_DATA) $$d/foo.info $(DESTDIR)$@@; \

# Run install-info only if it exists.

# Use `if' instead of just prepending `-' to the

# line so we notice real errors from install-info.

# We use `$(SHELL) -c' because some shells do not

# fail gracefully when there is an unknown command.

        if $(SHELL) -c 'install-info --version' \

           >/dev/null 2>&1; then \

          install-info --dir-file=$(DESTDIR)$(infodir)/dir \

                       $(DESTDIR)$(infodir)/foo.info; \

        else true; fi

@end smallexample

When writing the @code{install} target, you must classify all the

commands into three categories: normal ones, @dfn{pre-installation}

commands and @dfn{post-installation} commands.  @xref{Install Command

Categories}.

@item install-html

@itemx install-dvi

@itemx install-pdf

@itemx install-ps

These targets install documentation in formats other than Info;

they're intended to be called explicitly by the person installing the

package, if that format is desired.  GNU prefers Info files, so these

must be installed by the @code{install} target.

When you have many documentation files to install, we recommend that

you avoid collisions and clutter by arranging for these targets to

install in subdirectories of the appropriate installation directory,

such as @code{htmldir}.  As one example, if your package has multiple

manuals, and you wish to install HTML documentation with many files

(such as the ``split'' mode output by @code{makeinfo --html}), you'll

certainly want to use subdirectories, or two nodes with the same name

in different manuals will overwrite each other.

Please make these @code{install-@var{format}} targets invoke the

commands for the @var{format} target, for example, by making

@var{format} a dependency.

@item uninstall

Delete all the installed files---the copies that the @samp{install}

and @samp{install-*} targets create.

This rule should not modify the directories where compilation is done,

only the directories where files are installed.

The uninstallation commands are divided into three categories, just like

the installation commands.  @xref{Install Command Categories}.

@item install-strip

Like @code{install}, but strip the executable files while installing

them.  In simple cases, this target can use the @code{install} target in

a simple way:

@smallexample

install-strip:

        $(MAKE) INSTALL_PROGRAM='$(INSTALL_PROGRAM) -s' \

                install

@end smallexample

But if the package installs scripts as well as real executables, the

@code{install-strip} target can't just refer to the @code{install}

target; it has to strip the executables but not the scripts.

@code{install-strip} should not strip the executables in the build

directory which are being copied for installation.  It should only strip

the copies that are installed.

Normally we do not recommend stripping an executable unless you are sure

the program has no bugs.  However, it can be reasonable to install a

stripped executable for actual execution while saving the unstripped

executable elsewhere in case there is a bug.

@comment The gratuitous blank line here is to make the table look better

@comment in the printed Make manual.  Please leave it in.

@item clean

Delete all files in the current directory that are normally created by

building the program.  Also delete files in other directories if they

are created by this makefile.  However, don't delete the files that

record the configuration.  Also preserve files that could be made by

building, but normally aren't because the distribution comes with

them.  There is no need to delete parent directories that were created

with @samp{mkdir -p}, since they could have existed anyway.

Delete @file{.dvi} files here if they are not part of the distribution.

@item distclean

Delete all files in the current directory (or created by this

makefile) that are created by configuring or building the program.  If

you have unpacked the source and built the program without creating

any other files, @samp{make distclean} should leave only the files

that were in the distribution.  However, there is no need to delete

parent directories that were created with @samp{mkdir -p}, since they

could have existed anyway.

@item mostlyclean

Like @samp{clean}, but may refrain from deleting a few files that people

normally don't want to recompile.  For example, the @samp{mostlyclean}

target for GCC does not delete @file{libgcc.a}, because recompiling it

is rarely necessary and takes a lot of time.

@item maintainer-clean

Delete almost everything that can be reconstructed with this Makefile.

This typically includes everything deleted by @code{distclean}, plus

more: C source files produced by Bison, tags tables, Info files, and

so on.

The reason we say ``almost everything'' is that running the command

@samp{make maintainer-clean} should not delete @file{configure} even

if @file{configure} can be remade using a rule in the Makefile.  More

generally, @samp{make maintainer-clean} should not delete anything

that needs to exist in order to run @file{configure} and then begin to

build the program.  Also, there is no need to delete parent

directories that were created with @samp{mkdir -p}, since they could

have existed anyway.  These are the only exceptions;

@code{maintainer-clean} should delete everything else that can be

rebuilt.

The @samp{maintainer-clean} target is intended to be used by a maintainer of

the package, not by ordinary users.  You may need special tools to

reconstruct some of the files that @samp{make maintainer-clean} deletes.

Since these files are normally included in the distribution, we don't

take care to make them easy to reconstruct.  If you find you need to

unpack the full distribution again, don't blame us.

To help make users aware of this, the commands for the special

@code{maintainer-clean} target should start with these two:

@smallexample

@@echo 'This command is intended for maintainers to use; it'

@@echo 'deletes files that may need special tools to rebuild.'

@end smallexample

@item TAGS

Update a tags table for this program.

@c ADR: how?

@item info

Generate any Info files needed.  The best way to write the rules is as

follows:

@smallexample

info: foo.info

foo.info: foo.texi chap1.texi chap2.texi

        $(MAKEINFO) $(srcdir)/foo.texi

@end smallexample

@noindent

You must define the variable @code{MAKEINFO} in the Makefile.  It should

run the @code{makeinfo} program, which is part of the Texinfo

distribution.

Normally a GNU distribution comes with Info files, and that means the

Info files are present in the source directory.  Therefore, the Make

rule for an info file should update it in the source directory.  When

users build the package, ordinarily Make will not update the Info files

because they will already be up to date.

@item dvi

@itemx html

@itemx pdf

@itemx ps

Generate documentation files in the given format.  These targets

should always exist, but any or all can be a no-op if the given output

format cannot be generated.  These targets should not be dependencies

of the @code{all} target; the user must manually invoke them.

Here's an example rule for generating DVI files from Texinfo:

@smallexample

dvi: foo.dvi

foo.dvi: foo.texi chap1.texi chap2.texi

        $(TEXI2DVI) $(srcdir)/foo.texi

@end smallexample

@noindent

You must define the variable @code{TEXI2DVI} in the Makefile.  It should

run the program @code{texi2dvi}, which is part of the Texinfo

distribution.@footnote{@code{texi2dvi} uses @TeX{} to do the real work

of formatting. @TeX{} is not distributed with Texinfo.}  Alternatively,

write just the dependencies, and allow GNU @code{make} to provide the command.

Here's another example, this one for generating HTML from Texinfo:

@smallexample

html: foo.html

foo.html: foo.texi chap1.texi chap2.texi

        $(TEXI2HTML) $(srcdir)/foo.texi

@end smallexample

@noindent

Again, you would define the variable @code{TEXI2HTML} in the Makefile;