+File: standards.info, Node: Utilities in Makefiles, Next: Command Variables, Prev: Makefile Basics, Up: Makefile Conventions
+
+Utilities in Makefiles
+----------------------
+
+ Write the Makefile commands (and any shell scripts, such as
+`configure') to run in `sh', not in `csh'. Don't use any special
+features of `ksh' or `bash'.
+
+ The `configure' script and the Makefile rules for building and
+installation should not use any utilities directly except these:
+
+ 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
+
+ The compression program `gzip' can be used in the `dist' rule.
+
+ Stick to the generally supported options for these programs. For
+example, don't use `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 `make' variables
+so that the user can substitute alternatives. Here are some of the
+programs we mean:
+
+ ar bison cc flex install ld ldconfig lex
+ make makeinfo ranlib texi2dvi yacc
+
+ Use the following `make' variables to run those programs:
+
+ $(AR) $(BISON) $(CC) $(FLEX) $(INSTALL) $(LD) $(LDCONFIG) $(LEX)
+ $(MAKE) $(MAKEINFO) $(RANLIB) $(TEXI2DVI) $(YACC)
+
+ When you use `ranlib' or `ldconfig', you should make sure nothing
+bad happens if the system does not have the program in question.
+Arrange to ignore an error from that command, and print a message before
+the command to tell the user that failure of this command does not mean
+a problem. (The Autoconf `AC_PROG_RANLIB' macro can help with this.)
+
+ If you use symbolic links, you should implement a fallback for
+systems that don't have symbolic links.
+
+ Additional utilities that can be used via Make variables are:
+
+ chgrp chmod chown mknod
+
+ It is ok to use other utilities in Makefile portions (or scripts)
+intended only for particular systems where you know those utilities
+exist.
+
+\1f
+File: standards.info, Node: Command Variables, Next: Directory Variables, Prev: Utilities in Makefiles, Up: Makefile Conventions
+
+Variables for Specifying Commands
+---------------------------------
+
+ Makefiles should provide variables for overriding certain commands,
+options, and so on.
+
+ In particular, you should run most utility programs via variables.
+Thus, if you use Bison, have a variable named `BISON' whose default
+value is set with `BISON = bison', and refer to it with `$(BISON)'
+whenever you need to use Bison.
+
+ File management utilities such as `ln', `rm', `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 `FLAGS' to the
+program-name variable name to get the options variable name--for
+example, `BISONFLAGS'. (The names `CFLAGS' for the C compiler,
+`YFLAGS' for yacc, and `LFLAGS' for lex, are exceptions to this rule,
+but we keep them because they are standard.) Use `CPPFLAGS' in any
+compilation command that runs the preprocessor, and use `LDFLAGS' in
+any compilation command that does linking as well as in any direct use
+of `ld'.
+
+ If there are C compiler options that _must_ be used for proper
+compilation of certain files, do not include them in `CFLAGS'. Users
+expect to be able to specify `CFLAGS' freely themselves. Instead,
+arrange to pass the necessary options to the C compiler independently
+of `CFLAGS', by writing them explicitly in the compilation commands or
+by defining an implicit rule, like this:
+
+ CFLAGS = -g
+ ALL_CFLAGS = -I. $(CFLAGS)
+ .c.o:
+ $(CC) -c $(CPPFLAGS) $(ALL_CFLAGS) $<
+
+ Do include the `-g' option in `CFLAGS', because that is not
+_required_ for proper compilation. You can consider it a default that
+is only recommended. If the package is set up so that it is compiled
+with GCC by default, then you might as well include `-O' in the default
+value of `CFLAGS' as well.
+
+ Put `CFLAGS' last in the compilation command, after other variables
+containing compiler options, so the user can use `CFLAGS' to override
+the others.
+
+ `CFLAGS' should be used in every invocation of the C compiler, both
+those which do compilation and those which do linking.
+
+ Every Makefile should define the variable `INSTALL', which is the
+basic command for installing a file into the system.
+
+ Every Makefile should also define the variables `INSTALL_PROGRAM'
+and `INSTALL_DATA'. (The default for each of these should be
+`$(INSTALL)'.) Then it should use those variables as the commands for
+actual installation, for executables and nonexecutables respectively.
+Use these variables as follows:
+
+ $(INSTALL_PROGRAM) foo $(bindir)/foo
+ $(INSTALL_DATA) libfoo.a $(libdir)/libfoo.a
+
+ Optionally, you may prepend the value of `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 `DESTDIR' in your Makefile, and do not include it in
+any installed files. With support for `DESTDIR', the above examples
+become:
+
+ $(INSTALL_PROGRAM) foo $(DESTDIR)$(bindir)/foo
+ $(INSTALL_DATA) libfoo.a $(DESTDIR)$(libdir)/libfoo.a
+
+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.
+
+\1f
+File: standards.info, Node: Directory Variables, Next: Standard Targets, Prev: Command Variables, Up: Makefile Conventions
+
+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 are described below. They are based on a standard filesystem
+layout; variants of it are used in SVR4, 4.4BSD, Linux, Ultrix v4, and
+other modern operating systems.
+
+ 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.
+
+`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@'.)
+
+ 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.
+
+ Therefore, here are the variables Makefiles should use to specify
+directories:
+
+`datadir'
+ The directory for installing read-only architecture independent
+ data files. This should normally be `/usr/local/share', but write
+ it as `$(prefix)/share'. (If you are using Autoconf, write it as
+ `@datadir@'.) As a special exception, see `$(infodir)' and
+ `$(includedir)' below.
+
+`sysconfdir'
+ The directory for installing read-only data files that pertain to a
+ single machine-that is to say, files for configuring a host.
+ Mailer and network configuration files, `/etc/passwd', and so
+ forth belong here. All the files in this directory should be
+ ordinary ASCII text files. This directory should normally be
+ `/usr/local/etc', but write it as `$(prefix)/etc'. (If you are
+ using Autoconf, write it as `@sysconfdir@'.)
+
+ Do not install executables here in this directory (they probably
+ belong in `$(libexecdir)' or `$(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 `$(localstatedir)'.
+
+`sharedstatedir'
+ The directory for installing architecture-independent data files
+ which the programs modify while they run. This should normally be
+ `/usr/local/com', but write it as `$(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@'.)
+
+`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@'.)
+
+`infodir'
+ The directory for installing the Info files for this package. By
+ default, it should be `/usr/local/info', but it should be written
+ as `$(prefix)/info'. (If you are using Autoconf, write it as
+ `@infodir@'.)
+
+`lispdir'
+ The directory for installing any Emacs Lisp files in this package.
+ By default, it should be `/usr/local/share/emacs/site-lisp', but
+ it should be written as `$(prefix)/share/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.in' file:
+
+ lispdir='${datadir}/emacs/site-lisp'
+ AC_SUBST(lispdir)
+
+`includedir'
+ The directory for installing header files to be included by user
+ programs with the C `#include' preprocessor directive. This
+ should normally be `/usr/local/include', but write it as
+ `$(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.
+
+ 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/man', but you should
+ write it as `$(prefix)/man'. (If you are using Autoconf, write it
+ as `@mandir@'.)
+
+`man1dir'
+ The directory for installing section 1 man pages. Write it as
+ `$(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
+ 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 = $(prefix)/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.
+
+\1f
+File: standards.info, Node: Standard Targets, Next: Install Command Categories, Prev: Directory Variables, Up: Makefile Conventions