makedepend - create dependencies in makefiles
] [ -Dname
] [ -Yincludedir
] [ -a
] [ -include file
] [ -pobjprefix
] [ -wwidth
] [ -v
] [ -m
[ -- otheroptions
-- ] sourcefile
program reads each sourcefile
in sequence and
parses it like a C-preprocessor, processing all #include,
#define, #undef, #ifdef, #ifndef, #endif,
directives so that it can correctly
tell which #include,
directives would be used in a compilation. Any
directives can reference files having other #include
directives, and parsing will occur in these files as well.
Every file that a sourcefile
includes, directly or indirectly, is what
calls a dependency.
These dependencies are then
written to a makefile
in such a way that make(1)
will know which
object files must be recompiled when a dependency has changed.
By default, makedepend
places its output in the file named
if it exists, otherwise Makefile.
An alternate makefile
may be specified with the -f
option. It first searches the makefile for
# DO NOT DELETE THIS LINE -- make depend depends on it.
or one provided with the -s
option, as a delimiter for the dependency
output. If it finds it, it will delete everything following this to the end of
the makefile and put the output after this line. If it doesn't find it, the
program will append the string to the end of the makefile and place the output
following that. For each sourcefile
appearing on the command line,
puts lines in the makefile of the form
sourcefile.o: dfile ...
is the name from the command line with its suffix
replaced with ``.o'', and dfile
is a dependency discovered in a
directive while parsing sourcefile
or one of the files
will be used in a makefile target so that typing
``make depend'' will bring the dependencies up to date for the makefile. For
SRCS = file1.c file2.c ...
CFLAGS = -O -DHACK -I../foobar -xyz
makedepend -- $(CFLAGS) -- $(SRCS)
The program will ignore any option that it does not understand so that you may
use the same arguments that you would for cc(1).
- -Dname=def or -Dname
- Define. This places a definition for name in
makedepend's symbol table. Without =def the symbol becomes
defined as ``1''.
- Include directory. This option tells makedepend to
prepend includedir to its list of directories to search when it
encounters a #include directive. By default, makedepend only
searches the standard include directories (usually /usr/include and
possibly a compiler-dependent directory).
- Replace all of the standard include directories with the
single specified include directory; you can omit the includedir to
simply prevent searching the standard include directories.
- Append the dependencies to the end of the file instead of
- Filename. This allows you to specify an alternate makefile
in which makedepend can place its output. Specifying ``-'' as the
file name (i.e., -f-) sends the output to standard output instead
of modifying an existing file.
- -include file
- Process file as input, and include all the resulting output
before processing the regular input file. This has the same affect as if
the specified file is an include statement that appears before the very
first line of the regular input file.
- Object file suffix. Some systems may have object files
whose suffix is something other than ``.o''. This option allows you to
specify another suffix, such as ``.b'' with -o.b or ``:obj'' with
-o:obj and so forth.
- Object file prefix. The prefix is prepended to the name of
the object file. This is usually used to designate a different directory
for the object file. The default is the empty string.
- Starting string delimiter. This option permits you to
specify a different string for makedepend to look for in the
- Line width. Normally, makedepend will ensure that
every output line that it writes will be no wider than 78 characters for
the sake of readability. This option enables you to change this
- Verbose operation. This option causes makedepend to
emit the list of files included by each input file.
- Warn about multiple inclusion. This option causes
makedepend to produce a warning if any input file includes another
file more than once. In previous versions of makedepend this was
the default behavior; the default has been changed to better match the
behavior of the C compiler, which does not consider multiple inclusion to
be an error. This option is provided for backward compatibility, and to
aid in debugging problems related to multiple inclusion.
- -- options --
- If makedepend encounters a double hyphen (--) in the
argument list, then any unrecognized argument following it will be
silently ignored; a second double hyphen terminates this special
treatment. In this way, makedepend can be made to safely ignore
esoteric compiler arguments that might normally be found in a CFLAGS
make macro (see the EXAMPLE section above). All options that
makedepend recognizes and appear between the pair of double hyphens
are processed normally.
The approach used in this program enables it to run an order of magnitude faster
than any other ``dependency generator'' I have ever seen. Central to this
performance are two assumptions: that all files compiled by a single makefile
will be compiled with roughly the same -I
that most files in a single directory will include largely the same files.
Given these assumptions, makedepend
expects to be called once for each
makefile, with all source files that are maintained by the makefile appearing
on the command line. It parses each source and include file exactly once,
maintaining an internal symbol table for each. Thus, the first file on the
command line will take an amount of time proportional to the amount of time
that a normal C preprocessor takes. But on subsequent files, if it encounters
an include file that it has already parsed, it does not parse it again.
For example, imagine you are compiling two files, file1.c
they each include the header file header.h,
in turn includes the files def1.h
When you run the command
makedepend file1.c file2.c
will parse file1.c
and consequently, header.h
and then def1.h
It then decides that the
dependencies for this file are
file1.o: header.h def1.h def2.h
But when the program parses file2.c
and discovers that it, too, includes
it does not parse the file, but simply adds header.h,
to the list of dependencies for
parses, but does not currently evaluate, the SVR4
#predicate(token-list) preprocessor expression; such expressions are simply
assumed to be true. This may cause the wrong #include
directives to be
Imagine you are parsing two files, say file1.c
includes the file def.h.
The list of files that def.h
might truly be different when def.h
is included by file1.c
when it is included by file2.c.
But once makedepend
arrives at a
list of dependencies for a file, it is cast in concrete.
Todd Brunhoff, Tektronix, Inc. and MIT Project Athena