MirOS Manual: makedepend(1)


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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,

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         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 under-
     stand 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 direc-
          tories (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.

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     -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 mak-
          edepend 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 com-
          patibility, 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, mak-
          edepend 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

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     maintained by the makefile appearing on the command line. It
     parses each source and include file exactly once, maintain-
     ing 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 dependen-
     cies 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 sim-
     ply adds header.h, def1.h and def2.h to the list of depen-
     dencies for file2.o.

SEE ALSO

     cc(1), make(1)

BUGS

     makedepend parses, but does not currently evaluate, the SVR4
     #predicate(token-list) preprocessor expression; such expres-
     sions 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 mak-
     edepend arrives at a list of dependencies for a file, it is
     cast in concrete.

AUTHOR

     Todd Brunhoff, Tektronix, Inc. and MIT Project Athena

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