BitBake cheat sheet

1. Command-line options

Here are a few commonly-used command line options for BitBake.

Command-line 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
-b	execute tasks from a specific .bb recipe directly. This does not handle any dependencies from other recipes. bitbake -b ../meta-st/meta-st-cannes2/recipes-multimedia/gstreamer/gstreamer1.0-plugins-stm_local.bb -f -c compile
-v	show verbose output
-DDD	show lots of debug information
-s	show recipe version information
-e	output recipe environment variables bitbake -e <recipe>
--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 bitbake -g <recipe> dot -v -Tpng -o package-depends.png package-depends.dot dot -v -Tpng -o pn-depends.png pn-depends.dot dot -v -Tsvg -o task-depends.svg task-depends.dot

Here are a few examples of command line options for BitBake.

Main command lines commands

How to	Command	Comment
How to get the version of packages	bitbake -s
How to get the Image package list	bitbake <image> -g	Then: cat pn-buildlist
How to clean a module	bitbake <module> -f -c cleanall
How to clean an image	bitbake <image> - c cleanall
How to load the packages to a local hard drive	bitbake <image> -f -c fetchall
How to get the list of tasks	bitbake <image> -f -c listtasks
How to display all appends	bitbake-layers show-appends
How to display all layers	bitbake <recipe-or-image-name> -g -u depexp
How to configure the kernel	bitbake <kernel_module> -c menuconfig	kernel module : linux-stm32
How to make an SDK relocatable image	bitbake <image> -c populate_sdk	self-extracting image available in tmp-glibc/deploy/sdk

2. .bb file syntax

This table lists some of the syntaxes found in recipe (.bb) files.

.bb file 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 when parsing this line
VAR += "foo"	append with space
VAR =+ "foo"	prepend with space
VAR .= "foo"	append without space
VAR =. "foo"	prepend without space
VAR_append = "foo"	append 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"
OVERRIDES="string1:string2" VAR = "foo" VAR_append_string1 = " bar"	conditional append	if string1 is in OVERRIDES, then append " bar" to the value of VAR
BBVERSIONS="1.0 1.8 string" VAR="foo" VAR_string="bar"	range-specific conditional	If the version of the package is in the specified range (1.0-1.8 in this example), then perform an override on the indicated variable
VAR = "foo ${@<line-of-python-code>}"	python code expansion	ex: VAR = "the date is: ${@time.strftime(’%Y%m%d’,time.gmtime())}"
include foo	include file	include file named "foo", search BBPATH
require [<path>]foo	require file	include file named "foo", failing if not found exactly where specified
do_sometask() { <shell code> }	define a task using shell code
python do_sometask { <python code>	define a task using python code
addtask sometask (before|after) other_task	add a task	adds a defined task to the list of tasks, with a specific ordering. Zero or more 'before' or 'after' clauses can be used.
VAR [some_flag]="foo"	associate a subsidiary flag value to a variable	a few subsidiary flag value names are well-defined: "dirs", "cleandirs", "noexec", "nostamp", "fakeroot", "umask", "deptask", "rdeptask", "recdeptask", "recrdeptask" %%% Flag values appear to be used exclusively with task definitions (i.e. do_sometask)

3. Additional BitBake-related command

Additional BitBake-related command

Syntax	Meaning	Notes
bitbake-layers	Shows information about layers and recipes	Included in the bitbake/bin directory in openembedded source tree.
bitbake-whatchanged <image>	Shows all changes made since the last generation of image	bitbake st-image-weston # Edit the recipes bitbake-whatchanged st-image-weston
bitbake -g -u depexp <recipe-or-image-name>	Shows dependency information in a graphical interface
bitbake -u goggle st-image-weston	simple graphical interface	This is a simple graphical wrapper over the streaming text output of BitBake. It shows collapsible trees for the logs for sub-tasks for each recipe.

4. Useful links

• https://www.openembedded.org/wiki/BitBake_(user)
• http://www.openembedded.org/wiki/Main_Page
• Yocto Project Develpoment Manual
• BitBake User Manual

Software development kit (A programming package that enables a programmer to develop applications for a specific platform.)