(automk14.info.gz) A Program

 
 7.1 Building a program
 ======================
 
 In a directory containing source that gets built into a program (as
 opposed to a library), the `PROGRAMS' primary is used.  Programs can be
 installed in `bindir', `sbindir', `libexecdir', `pkglibdir', or not at
 all (`noinst').
 
    For instance:
 
      bin_PROGRAMS = hello
 
    In this simple case, the resulting `Makefile.in' will contain code
 to generate a program named `hello'.  The variable `hello_SOURCES' is
 used to specify which source files get built into an executable:
 
      hello_SOURCES = hello.c version.c getopt.c getopt1.c getopt.h system.h
 
    This causes each mentioned `.c' file to be compiled into the
 corresponding `.o'.  Then all are linked to produce `hello'.
 
    If `PROG_SOURCES' is needed, but not specified, then it defaults to
 the single file `prog.c'.  
 
    Multiple programs can be built in a single directory.  Multiple
 programs can share a single source file, which must be listed in each
 `_SOURCES' definition.
 
    Header files listed in a `_SOURCES' definition will be included in
 the distribution but otherwise ignored.  In case it isn't obvious, you
 should not include the header file generated by `configure' in an
 `_SOURCES' variable; this file should not be distributed.  Lex (`.l')
 and Yacc (`.y') files can also be listed; see  Yacc and Lex.
 
    Automake must know all the source files that could possibly go into a
 program, even if not all the files are built in every circumstance.
 Any files which are only conditionally built should be listed in the
 appropriate `EXTRA_' variable.  For instance, if `hello-linux.c' were
 conditionally included in `hello', the `Makefile.am' would contain:
 
      EXTRA_hello_SOURCES = hello-linux.c
 
    Similarly, sometimes it is useful to determine the programs that are
 to be built at configure time.  For instance, GNU `cpio' only builds
 `mt' and `rmt' under special circumstances.
 
    In this case, you must notify Automake of all the programs that can
 possibly be built, but at the same time cause the generated
 `Makefile.in' to use the programs specified by `configure'.  This is
 done by having `configure' substitute values into each `_PROGRAMS'
 definition, while listing all optionally built programs in
 `EXTRA_PROGRAMS'.  
 
    If you need to link against libraries that are not found by
 `configure', you can use `LDADD' to do so.  This variable actually can
 be used to add any options to the linker command line.  
 
    Sometimes, multiple programs are built in one directory but do not
 share the same link-time requirements.  In this case, you can use the
 `PROG_LDADD' variable (where PROG is the name of the program as it
 appears in some `_PROGRAMS' variable, and usually written in lowercase)
 to override the global `LDADD'.  If this variable exists for a given
 program, then that program is not linked using `LDADD'.  
 
    For instance, in GNU cpio, `pax', `cpio' and `mt' are linked against
 the library `libcpio.a'.  However, `rmt' is built in the same
 directory, and has no such link requirement.  Also, `mt' and `rmt' are
 only built on certain architectures.  Here is what cpio's
 `src/Makefile.am' looks like (abridged):
 
      bin_PROGRAMS = cpio pax @MT@
      libexec_PROGRAMS = @RMT@
      EXTRA_PROGRAMS = mt rmt
 
      LDADD = ../lib/libcpio.a @INTLLIBS@
      rmt_LDADD =
 
      cpio_SOURCES = ...
      pax_SOURCES = ...
      mt_SOURCES = ...
      rmt_SOURCES = ...
 
    `PROG_LDADD' is inappropriate for passing program-specific linker
 flags (except for `-l' and `-L').  So, use the `PROG_LDFLAGS' variable
 for this purpose.  
 
    It is also occasionally useful to have a program depend on some other
 target which is not actually part of that program.  This can be done
 using the `PROG_DEPENDENCIES' variable.  Each program depends on the
 contents of such a variable, but no further interpretation is done.
 
    If `PROG_DEPENDENCIES' is not supplied, it is computed by Automake.
 The automatically-assigned value is the contents of `PROG_LDADD', with
 most configure substitutions, `-l', and `-L' options removed.  The
 configure substitutions that are left in are only `@LIBOBJS@' and
 `@ALLOCA@'; these are left because it is known that they will not cause
 an invalid value for `PROG_DEPENDENCIES' to be generated.
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