@cindex conventions for makefiles
@cindex standards for makefiles
-@c Copyright (C) 1992, 1993, 1994, 1995, 1996, 1997, 1998, 2000, 2001,
-@c 2004, 2005 Free Software Foundation, Inc.
-
+@c Copyright 1992, 1993, 1994, 1995, 1996, 1997, 1998, 2000, 2001,
+@c 2004, 2005, 2006, 2007, 2008 Free Software Foundation, Inc.
+@c
@c Permission is granted to copy, distribute and/or modify this document
-@c under the terms of the GNU Free Documentation License, Version 1.1
+@c under the terms of the GNU Free Documentation License, Version 1.3
@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.
@end iftex
describes conventions for writing the Makefiles for GNU programs.
Using Automake will help you write a Makefile that follows these
-conventions.
+conventions. For more information on portable Makefiles, see
+@sc{posix} and @ref{Portable Make, Portable Make Programming,, autoconf,
+Autoconf}.
+
@menu
-* Makefile Basics:: General Conventions for Makefiles
-* Utilities in Makefiles:: Utilities in Makefiles
-* Command Variables:: Variables for Specifying Commands
-* Directory Variables:: Variables for Installation Directories
-* Standard Targets:: Standard Targets for Users
+* 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
@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}.
+@code{configure}) to run under @code{sh} (both the traditional Bourne
+shell and the @sc{posix} shell), not @code{csh}. Don't use any
+special features of @code{ksh} or @code{bash}, or @sc{posix} features
+not widely supported in traditional Bourne @code{sh}.
The @code{configure} script and the Makefile rules for building and
installation should not use any utilities directly except these:
@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
+awk cat cmp cp diff echo egrep expr false grep install-info
+ln ls mkdir mv pwd rm rmdir sed sleep sort tar test touch tr true
@end example
-The compression program @code{gzip} can be used in the @code{dist} rule.
+Compression programs such as @code{gzip} can be used in the
+@code{dist} rule.
+
+Generally, stick to the widely-supported (usually
+@sc{posix}-specified) options and features of these programs. For
+example, don't use @samp{mkdir -p}, convenient as it may be, because a
+few systems don't support it at all and with others, it is not safe
+for parallel execution. For a list of known incompatibilities, see
+@ref{Portable Shell, Portable Shell Programming,, autoconf, Autoconf}.
-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.
+few file 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
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 nonexecutables
-respectively. Use these variables as follows:
+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 $(libdir)/libfoo.a
@end example
-Optionally, you may prepend the value of @code{DESTDIR} to the target
-filename. Doing this allows the installer to create a snapshot of the
-installation to be copied onto the real target filesystem later. Do not
-set the value of @code{DESTDIR} in your Makefile, and do not include it
-in any installed files. With support for @code{DESTDIR}, the above
-examples become:
+However, it is preferable to support a @code{DESTDIR} prefix on the
+target files, as explained in the next section.
+
+It is acceptable, but not required, to install multiple files in one
+command, with the final argument being a directory, as in:
+
+@example
+$(INSTALL_PROGRAM) foo bar baz $(bindir)
+@end example
+
+
+@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 as an absolute file name. For example:
+
+@example
+make DESTDIR=/tmp/stage install
+@end example
+
@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.
+@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 filesystem layout;
+described below. They are based on a standard file system layout;
variants of it are used in GNU/Linux and other modern operating
systems.
default settings specified here so that all GNU packages behave
identically, allowing the installer to achieve any desired layout.
-These 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.
+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
@itemx pdfdir
@itemx psdir
Directories for installing documentation files in the particular
-format. (It is not required to support documentation in all these
-formats.) They should all be set to @code{$(docdir)} by default. (If
+format. They should all be set to @code{$(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
@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 Autconf, use @samp{srcdir = @@srcdir@@}.)
+(If you are using Autoconf, use @samp{srcdir = @@srcdir@@}.)
@end table
For example:
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
@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 files should be made
-only when explicitly asked for.
+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
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 roland@gnu.ai.mit.edu.
+@comment Please do not reformat it without talking to bug-make@gnu.org.
@smallexample
$(DESTDIR)$(infodir)/foo.info: foo.info
$(POST_INSTALL)
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.
@itemx html
@itemx pdf
@itemx ps
-Generate documentation files in the given format, if possible.
+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
Compress the tar file with @code{gzip}. For example, the actual
distribution file for GCC version 1.40 is called @file{gcc-1.40.tar.gz}.
+It is ok to support other free compression formats as well, such as
+@code{bzip2} and @code{lzma}.
The @code{dist} target should explicitly depend on all non-source files
that are in the distribution, to make sure they are up to date in the