Ubuntu Manpage: makedepend - create dependencies in makefiles

NAME

       makedepend - create dependencies in makefiles

SYNOPSIS

       makedepend [ -Dname=def ] [ -Dname ] [ -Iincludedir ] [ -Yincludedir ]
           [ -a ] [ -fmakefile ] [ -include file ] [ -oobjsuffix ]
           [ -pobjprefix ] [ -sstring ] [ -wwidth ] [ -v ] [ -m ]
           [ -- otheroptions -- ] sourcefile ...

DESCRIPTION

       The  makedepend program reads each sourcefile in sequence and parses it like a C-preprocessor, processing
       all #include, #define, #undef, #ifdef, #ifndef, #endif, #if, #elif and #else directives so  that  it  can
       correctly  tell  which #include, directives would be used in a compilation.  Any #include, 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  makedepend  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 makefile if it exists, otherwise Makefile.  An
       alternate makefile may be specified with the -f option.  It first searches the makefile for the line

           # 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, makedepend puts lines in the makefile
       of the form

            sourcefile.o: dfile ...

       Where sourcefile.o is the name from the command line with its suffix replaced with ``.o'', and dfile is a
       dependency discovered in a #include directive while parsing sourcefile or one of the files it included.

EXAMPLE

       Normally, makedepend will be used in a makefile target so that typing  ``make  depend''  will  bring  the
       dependencies up to date for the makefile.  For example,
           SRCS = file1.c file2.c ...
           CFLAGS = -O -DHACK -I../foobar -xyz
           depend:
                   makedepend -- $(CFLAGS) -- $(SRCS)

OPTIONS

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''.

-Iincludedir
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).

-Yincludedir
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.

-a Append the dependencies to the end of the file instead of replacing them.

-fmakefile
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.

-oobjsuffix
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.

-pobjprefix
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.

-sstring
Starting string delimiter. This option permits you to specify a different string for makedepend to
look for in the makefile.

-wwidth
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 width.

-v Verbose operation. This option causes makedepend to emit the list of files included by each input
file.

-m 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.

ALGORITHM

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 and -D options; and 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 and file2.c, they each include the header file
header.h, and the file header.h in turn includes the files def1.h and def2.h. When you run the command

makedepend file1.c file2.c

makedepend will parse file1.c and consequently, header.h and then def1.h and def2.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 header.h, it does not parse the
file, but simply adds header.h, def1.h and def2.h to the list of dependencies for file2.o.

BUGS

       makedepend 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 evaluated.

       Imagine  you  are  parsing two files, say file1.c and file2.c, each includes the file def.h.  The list of
       files that def.h includes might truly be different when def.h is included by  file1.c  than  when  it  is
       included  by  file2.c.   But  once makedepend arrives at a list of dependencies for a file, it is cast in
       concrete.

AUTHOR

       Todd Brunhoff, Tektronix, Inc. and MIT Project Athena

4th Berkeley Distribution                       makedepend 1.0.8                                   MAKEDEPEND(1)