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CRUNCHGEN(1)		FreeBSD	General	Commands Manual		  CRUNCHGEN(1)

     crunchgen -- generates build environment for a crunched binary

     crunchgen [-foql] [-h makefile-header-name] [-m makefile-name]
	       [-p obj-prefix] [-c c-file-name]	[-e exec-file-name] conf-file

     A crunched	binary is a program made up of many other programs linked to-
     gether into a single executable.  The crunched binary main() function de-
     termines which component program to run by	the contents of	argv[0].  The
     main reason to crunch programs together is	for fitting as many programs
     as	possible onto an installation or system	recovery floppy.

     The crunchgen utility reads in the	specifications in conf-file for	a
     crunched binary, and generates a Makefile and accompanying	top-level C
     source file that when built creates the crunched executable file from the
     component programs.  For each component program, crunchgen	can optionally
     attempt to	determine the object (.o) files	that make up the program from
     its source	directory Makefile.  This information is cached	between	runs.
     The crunchgen utility uses	the companion program crunchide(1) to elimi-
     nate link-time conflicts between the component programs by	hiding all un-
     necessary symbols.

     The crunchgen utility places specific requirements	on package Makefiles
     which make	it unsuitable for use with non-BSD sources.  In	particular,
     the Makefile must contain the target depend, and it must define all ob-
     ject files	in the variable	OBJS.  In some cases, you can use a fake
     Makefile: before looking for Makefile in the source directory foo,
     crunchgen looks for the file in the current directory.

     After crunchgen is	run, the crunched binary can be	built by running "make
     -f	<conf-name>.mk".  The component	programs' object files must already be
     built.  An	objs target, included in the output makefile, will run make(1)
     in	each component program's source	dir to build the object	files for the
     user.  This is not	done automatically since in release engineering	cir-
     cumstances	it is generally	not desirable to be modifying objects in other

     The options are as	follows:

     -c	c-file-name
	     Set output	C file name to c-file-name.  The default name is

     -e	exec-file-name
	     Set crunched binary executable file name to exec-file-name.  The
	     default name is _conf-name_.

     -f	     Flush cache.  Forces the recalculation of cached parameters.

     -l	     List names.  Lists	the names this binary will respond to.

     -h	makefile-header-name
	     Set the name of a file to be included at the beginning of the
	     Makefiles generated by crunchgen.	This is	useful to define some
	     make variables which might	affect the behavior of make(1) and are
	     annoying to pass through environment variables.

     -m	makefile-name
	     Set output	Makefile name to makefile-name.	 The default name is

     -o	     Add "make obj" rules to each program make target.

     -p	obj-prefix
	     Set the pathname to be prepended to the srcdir when computing the
	     objdir.  If this option is	not present, then the prefix used is
	     the content of the	MAKEOBJDIRPREFIX environment variable, or

     -q	     Quiet operation.  Status messages are suppressed.

     The crunchgen utility reads specifications	from the conf-file that	de-
     scribe the	components of the crunched binary.  In its simplest use, the
     component program names are merely	listed along with the top-level	source
     directories in which their	sources	can be found.  The crunchgen utility
     then calculates (via the source makefiles)	and caches the list of object
     files and their locations.	 For more specialized situations, the user can
     specify by	hand all the parameters	that crunchgen needs.

     The conf-file commands are	as follows:

     srcdirs dirname ...
	     A list of source trees in which the source	directories of the
	     component programs	can be found.  These dirs are searched using
	     the BSD "_source-dir_/_progname_/"	convention.  Multiple srcdirs
	     lines can be specified.  The directories are searched in the or-
	     der they are given.

     progs progname ...
	     A list of programs	that make up the crunched binary.  Multiple
	     progs lines can be	specified.

     libs libspec ...
	     A list of library specifications to be included in	the crunched
	     binary link.  Multiple libs lines can be specified.

     libs_so libspec ...
	     A list of library specifications to be dynamically	linked in the
	     crunched binary.  These libraries will need to be made available
	     via the run-time link-editor rtld(1) when the component program
	     that requires them	is executed from the crunched binary.  Multi-
	     ple libs_so lines can be specified.  The libs_so directive	over-
	     rides a library specified gratuitously on a libs line.

     buildopts buildopts ...
	     A list of build options to	be added to every make target.

     ln	progname linkname
	     Causes the	crunched binary	to invoke progname whenever linkname
	     appears in	argv[0].  This allows programs that change their be-
	     havior when run under different names to operate correctly.

     To	handle specialized situations, such as when the	source is not avail-
     able or not built via a conventional Makefile, the	following special com-
     mands can be used to set crunchgen	parameters for a component program.

     special progname srcdir pathname
	     Set the source directory for progname.  This is normally calcu-
	     lated by searching	the specified srcdirs for a directory named

     special progname objdir pathname
	     Set the obj directory for progname.  The obj directory is nor-
	     mally calculated by looking for a directory whose name is that of
	     the source	directory prepended by one of the following compo-
	     nents, in order of	priority: the -p argument passed to the	com-
	     mand line;	or, the	value of the MAKEOBJDIRPREFIX environment
	     variable, or /usr/obj.  If	the directory is not found, the	srcdir
	     itself becomes the	objdir.

     special progname buildopts	buildopts
	     Define a set of build options that	should be added	to make(1)
	     targets in	addition to those specified using buildopts when pro-
	     cessing progname.

     special progname objs object-file-name ...
	     Set the list of object files for program progname.	 This is nor-
	     mally calculated by constructing a	temporary makefile that	in-
	     cludes "srcdir/Makefile" and outputs the value of $(OBJS).

     special progname objpaths full-pathname-to-object-file ...
	     Sets the pathnames	of the object files for	program	progname.
	     This is normally calculated by prepending the objdir pathname to
	     each file in the objs list.

     special progname objvar variable_name
	     Sets the name of the make(1) variable which holds the list	of ob-
	     ject files	for program progname.  This is normally	OBJS but some
	     Makefiles might like to use other conventions or prepend the pro-
	     gram's name to the	variable, e.g.,	SSHD_OBJS.

     special progname lib library-name ...
	     Specifies libraries to be linked with object files	to produce
	     progname.lo.  This	can be useful with libraries which redefine
	     routines in the standard libraries, or poorly written libraries
	     which reference symbols in	the object files.

     special progname keep symbol-name ...
	     Add specified list	of symbols to the keep list for	program
	     progname.	An underscore (`_') is prepended to each symbol	and it
	     becomes the argument to a -k option for the crunchide(1) phase.
	     This option is to be used as a last resort	as its use can cause a
	     symbol conflict, however in certain instances it may be the only
	     way to have a symbol resolve.

     special progname ident identifier
	     Set the Makefile/C	identifier for progname.  This is normally
	     generated from a progname,	mapping	`-' to `_' and ignoring	all
	     other non-identifier characters.  This leads to programs named
	     "" and "foobar" to map to the same identifier.

     Only the objpaths parameter is actually needed by crunchgen, but it is
     calculated	from objdir and	objs, which are	in turn	calculated from
     srcdir, so	is sometimes convenient	to specify the earlier parameters and
     let crunchgen calculate forward from there	if it can.

     The makefile produced by crunchgen	contains an optional objs target that
     will build	the object files for each component program by running make(1)
     inside that program's source directory.  For this to work the srcdir and
     objs parameters must also be valid.  If they are not valid	for a particu-
     lar program, that program is skipped in the objs target.

     Here is an	example	crunchgen input	conf file, named "kcopy.conf":

	   srcdirs /usr/src/bin	/usr/src/sbin

	   progs test cp echo sh fsck halt init	mount umount myinstall
	   progs anotherprog
	   ln test [	   # test can be invoked via [
	   ln sh -sh	   # init invokes the shell with "-sh" in argv[0]

	   special myprog objpaths /homes/leroy/src/myinstall.o	# no sources

	   special anotherprog -DNO_FOO	WITHOUT_BAR=YES

	   libs	-lutil -lcrypt

     This conf file specifies a	small crunched binary consisting of some basic
     system utilities plus a homegrown install program "myinstall", for	which
     no	source directory is specified, but its object file is specified	di-
     rectly with the special line.

     Additionally when "anotherprog" is	built the arguments


     are added to all build targets.

     The crunched binary "kcopy" can be	built as follows:

	   % crunchgen -m Makefile kcopy.conf	 # gen Makefile	and kcopy.c
	   % make objs		   # build the component programs' .o files
	   % make		   # build the crunched	binary kcopy
	   % kcopy sh		   # test that this invokes a sh shell
	   $			   # it	works!

     At	this point the binary "kcopy" can be copied onto an install floppy and
     hard-linked to the	names of the component programs.

     Note that if the libs_so command had been used, copies of the libraries
     so	named would also need to be copied to the install floppy.

     crunchide(1), make(1), rtld(1)

     The crunchgen utility was written by James	da Silva <>.

     Copyright (c) 1994	University of Maryland.	 All Rights Reserved.

     The libs_so keyword was added in 2005 by Adrian Steinmann <>
     and Ceri Davies <>.

     While crunchgen takes care	to eliminate link conflicts between the	compo-
     nent programs of a	crunched binary, conflicts are still possible between
     the libraries that	are linked in.	Some shuffling in the order of li-
     braries may be required, and in some rare cases two libraries may have an
     unresolvable conflict and thus cannot be crunched together.

     Some versions of the BSD build environment	do not by default build	the
     intermediate object file for single-source	file programs.	The "make
     objs" must	then be	used to	get those object files built, or some other
     arrangements made.

FreeBSD	13.0			January	6, 2017			  FreeBSD 13.0


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