Bitbake Cheat Sheet

Here are some quick notes on bitbake syntax and rules. For an exhaustive list of functionality, and longer descriptions, see the bitbake manual at: http://docs.openembedded.org/bitbake/html/ (note that this link goes to the OpenEmbedded version of the bitbake manual, which is a version from 2006 as of this writing. A separate (yocto-specific?) bitbake manual is included in source form in the yocto project source directory, under bitbake/doc.)

Options

Option	Meaning
-c <task>	execute <task> for the image or recipe being built. ex: bitbake -c fetch busybox. Some of the possible tasks are: fetch, configure, compile, package, clean
-f	force execution of the operation, even if not required
-v	show verbose output
-DDD	show lots of debug information
-s	show recipe version information
--help	get usage help
-c listtasks <image-or-recipe-name>	show the tasks associated with an image or individual recipe
-g <recipe>	output dependency tree in graphviz format

Syntax

Syntax	Meaning	NOTES
VAR = "foo"	simple assignment
VAR ?= "foo"	assign if no other value is already assigned (default assignment)
VAR ??=foo	weak default assignment	takes lower precedence than ?=
VAR = "stuff ${OTHER_VAR} more"	variable expansion	OTHER_VAR expanded at time of reference to VAR
VAR := "stuff ${OTHER_VAR} more"	immediate variable expansion	OTHER_VAR expanded at time of parsing this line
VAR += "foo"	append with space
VAR =+ "foo"	prepend with space
VAR .= "foo"	append without space
VAR =. "foo"	prepend without space
OVERRIDES="string1:string2" VAR = "foo" VAR_string1 = "bar"	alternate/override value	if string1 is listed in OVERRIDES, use "bar" for value of VAR, otherwise use "foo"
OVERRIDS="string1:string2" VAR = "foo" VAR_appends_string1 = " bar"	conditional appending	if string1 in in OVERRIDES, then append " bar" to the value of VAR