BitBake cheat sheet

1 Command-line options[edit]

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/  -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
 dot -v -Tpng -o pn-depends.png
 dot -v -Tsvg -o task-depends.svg

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[edit]

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[edit]

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[edit]

Software development kit