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 uses 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:
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
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 uses imake extensively, for both full builds within
the source tree and external software. 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):
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.
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.
FILES
Imakefile.ctemporary input file for cpp
/tmp/Imf.XXXXXXtemporary Makefile for -s
/tmp/IIf.XXXXXXtemporary Imakefile if specified Imakefile uses # comments
/usr/bin/cppdefault C preprocessor
SEE ALSO
make(1), xmkmf(1)
S. I. Feldman,
Make --- A Program for Maintaining Computer Programs
ENVIRONMENT VARIABLES
The following environment variables may be set, however their use is not
recommended as they introduce dependencies that are not readily apparent
when imake is run:
IMAKEINCLUDE
If defined, this specifies a ``-I'' include argument to pass to the
C preprocessor. E.g., ``-I/usr/X11/config''.
IMAKECPP
If defined, this should be a valid path to a preprocessor program.
E.g., ``/usr/local/cpp''.
By default,
imake
will use cc -E or /usr/bin/cpp, depending on the OS specific configuration.
IMAKEMAKE
If defined, this should be a valid path to a make program,
such as ``/usr/local/make''.
By default,
imake
will use whatever
make
program is found using
execvp(3).
This variable is only used if the ``-e'' option is specified.
AUTHOR
Todd Brunhoff, Tektronix and MIT Project Athena; Jim Fulton, MIT X Consortium