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PROGRAM:

NAME

imake - C preprocessor interface to the make utility

SYNOPSIS

imake [ -Ddefine ] [ -Idir ] [ -Udefine ] [ -Ttemplate ] [ -f filename ] [ -C filename ] [
-s filename ] [ -e ] [ -v ]

DESCRIPTION

Imake is used to generate Makefiles from a template, a set of cpp macro functions, and a
per-directory input file called an Imakefile. This allows machine dependencies (such as
compiler options, alternate command names, and special make rules) to be kept separate
from the descriptions of the various items to be built.

OPTIONS

The following command line options may be passed to imake:

-Ddefine
This option is passed directly to cpp. It is typically used to set directory-
specific variables. For example, the X Window System used this flag to set TOPDIR
to the name of the directory containing the top of the core distribution and
CURDIR to the name of the current directory, relative to the top.

-Idirectory
This option is passed directly to cpp. It is typically used to indicate the
directory in which the imake template and configuration files may be found.

-Udefine
This option is passed directly to cpp. It is typically used to unset variables
when debugging imake configuration files.

-Ttemplate
This option specifies the name of the master template file (which is usually
located in the directory specified with -I) used by cpp. The default is
Imake.tmpl.

-f filename
This option specifies the name of the per-directory input file. The default is
Imakefile.

-C filename
This option specifies the name of the .c file that is constructed in the current
directory. The default is Imakefile.c.

-s filename
This option specifies the name of the make description file to be generated but
make should not be invoked. If the filename is a dash (-), the output is written
to stdout. The default is to generate, but not execute, a Makefile.

-e This option indicates the imake should execute the generated Makefile. The
default is to leave this to the user.

-v This option indicates that imake should print the cpp command line that it is
using to generate the Makefile.

HOW IT WORKS

Imake invokes cpp with any -I or -D flags passed on the command line and passes the name
of a file containing the following 3 lines:

#define IMAKE_TEMPLATE "Imake.tmpl"
#define INCLUDE_IMAKEFILE <Imakefile>
#include IMAKE_TEMPLATE

where Imake.tmpl and Imakefile may be overridden by the -T and -f command options,
respectively.

The IMAKE_TEMPLATE typically reads in a file containing machine-dependent parameters
(specified as cpp symbols), a site-specific parameters file, a file defining variables, a
file containing cpp macro functions for generating make rules, and finally the Imakefile
(specified by INCLUDE_IMAKEFILE) in the current directory. The Imakefile uses the macro
functions to indicate what targets should be built; imake takes care of generating the
appropriate rules.

Imake configuration files contain two types of variables, imake variables and make
variables. The imake variables are interpreted by cpp when imake is run. By convention
they are mixed case. The make variables are written into the Makefile for later
interpretation by make. By convention make variables are upper case.

The rules file (usually named Imake.rules in the configuration directory) contains a
variety of cpp macro functions that are configured according to the current platform.
Imake replaces any occurrences of the string ``@@'' with a newline to allow macros that
generate more than one line of make rules. For example, the macro

#define program_target(program, objlist) @@
program: objlist @@
$(CC) -o $@ objlist $(LDFLAGS)

when called with program_target(foo, foo1.o foo2.o) will expand to

foo: foo1.o foo2.o
$(CC) -o $@ foo1.o foo2.o $(LDFLAGS)

Imake also replaces any occurrences of the word ``XCOMM'' with the character ``#'' to
permit placing comments in the Makefile without causing ``invalid directive'' errors from
the preprocessor.

Some complex imake macros require generated make variables local to each invocation of the
macro, often because their value depends on parameters passed to the macro. Such
variables can be created by using an imake variable of the form XVARdefn, where n is a
single digit. A unique make variable will be substituted. Later occurrences of the
variable XVARusen will be replaced by the variable created by the corresponding XVARdefn.

On systems whose cpp reduces multiple tabs and spaces to a single space, imake attempts to
put back any necessary tabs (make is very picky about the difference between tabs and
spaces). For this reason, colons (:) in command lines must be preceded by a backslash
(\).

USE WITH THE X WINDOW SYSTEM

The X Window System used imake extensively up through the X11R6.9 release, for both full
builds within the source tree and external software. X has since moved to GNU autoconf
and automake for its build system in X11R7.0 and later releases, but still maintains imake
for building existing external software programs that have not yet converted.

As mentioned above, two special variables, TOPDIR and CURDIR, are set to make referencing
files using relative path names easier. For example, the following command is generated
automatically to build the Makefile in the directory lib/X/ (relative to the top of the
sources):

% ../.././config/imake -I../.././config
-DTOPDIR=../../. -DCURDIR=./lib/X
When building X programs outside the source tree, a special symbol UseInstalled is defined
and TOPDIR and CURDIR are omitted. If the configuration files have been properly
installed, the script xmkmf(1) may be used.

INPUT FILES

Here is a summary of the files read by imake as used by X. The indentation shows what
files include what other files.
Imake.tmpl generic variables
site.def site-specific, BeforeVendorCF defined
*.cf machine-specific
*Lib.rules shared library rules
site.def site-specific, AfterVendorCF defined
Imake.rules rules
Project.tmpl X-specific variables
*Lib.tmpl shared library variables
Imakefile
Library.tmpl library rules
Server.tmpl server rules
Threads.tmpl multi-threaded rules

Note that site.def gets included twice, once before the *.cf file and once after.
Although most site customizations should be specified after the *.cf file, some, such as
the choice of compiler, need to be specified before, because other variable settings may
depend on them.

The first time site.def is included, the variable BeforeVendorCF is defined, and the
second time, the variable AfterVendorCF is defined. All code in site.def should be inside
an #ifdef for one of these symbols.

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