This directory contains the pw command line interface (CLI) that facilitates working with Pigweed. The CLI module adds several subcommands prefixed with pw, and provides a mechanism for other Pigweed modules to behave as “plugins” and register themselves as pw commands as well. After activating the Pigweed environment, these commands will be available for use.

pw includes the following commands by default:

doctor        Check that the environment is set up correctly for Pigweed.
format        Check and fix formatting for source files.
help          Display detailed information about pw commands.
logdemo       Show how logs look at various levels.
module-check  Check that a module matches Pigweed's module guidelines.
test          Run Pigweed unit tests built using GN.
watch         Watch files for changes and rebuild.

To see an up-to-date list of pw subcommands, run pw --help.

Invoking pw

pw subcommands are invoked by providing the command name. Arguments prior to the command are interpreted by pw itself; all arguments after the command name are interpreted by the command.

Here are some example invocations of pw:

# Run the doctor command
$ pw doctor

# Run format --fix with debug-level logs
$ pw --loglevel debug format --fix

# Display help for the pw command
$ pw -h watch

# Display help for the watch command
$ pw watch -h

Registering pw plugins

Projects can register their own Python scripts as pw commands. pw plugins are registered by providing the command name, module, and function in a PW_PLUGINS file. PW_PLUGINS files can add new commands or override built-in commands. Since they are accessed by module name, plugins must be defined in Python packages that are installed in the Pigweed virtual environment.

Plugin registrations in a PW_PLUGINS file apply to the their directory and all subdirectories, similarly to configuration files like .clang-format. Registered plugins appear as commands in the pw tool when pw is run from those directories.

Projects that wish to register commands might place a PW_PLUGINS file in the root of their repo. Multiple PW_PLUGINS files may be applied, but the pw tool gives precedence to a PW_PLUGINS file in the current working directory or the nearest parent directory.

PW_PLUGINS file format

PW_PLUGINS contains one plugin entry per line in the following format:

# Lines that start with a # are ignored.
<command name> <Python module> <function>

The following example registers three commands:

# Register the presubmit script as pw presubmit
presubmit run_presubmit

# Override the pw test command with a custom version
test my_cool_project.testing run_test

# Add a custom command
flash my_cool_project.flash main

Defining a plugin function

Any function without required arguments may be used as a plugin function. The function should return an int, which the pw uses as the exit code. The pw tool uses the function docstring as the help string for the command.

Typically, pw commands parse their arguments with the argparse module. pw sets sys.argv so it contains only the arguments for the plugin, so plugins can behave the same whether they are executed independently or through pw.


This example shows a function that is registered as a pw plugin.

# my_package/

def _do_something(device):

def main() -> int:
    """Do something to a connected device."""

    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument('--device', help='Set which device to target')
    return _do_something(**vars(parser.parse_args()))

if __name__ == '__main__':
    logging.basicConfig(format='%(message)s', level=logging.INFO)

This plugin is registered in a PW_PLUGINS file in the current working directory or a parent of it.

# Register my_commmand
my_command my_package.my_module main

The function is now available through the pw command, and will be listed in pw’s help. Arguments after the command name are passed to the plugin.

$ pw

 ▒█████▄   █▓  ▄███▒  ▒█    ▒█ ░▓████▒ ░▓████▒ ▒▓████▄
  ▒█░  █░ ░█▒ ██▒ ▀█▒ ▒█░ █ ▒█  ▒█   ▀  ▒█   ▀  ▒█  ▀█▌
  ▒█▄▄▄█░ ░█▒ █▓░ ▄▄░ ▒█░ █ ▒█  ▒███    ▒███    ░█   █▌
  ▒█▀     ░█░ ▓█   █▓ ░█░ █ ▒█  ▒█   ▄  ▒█   ▄  ░█  ▄█▌
  ▒█      ░█░ ░▓███▀   ▒█▓▀▓█░ ░▓████▒ ░▓████▒ ▒▓████▀

usage: pw [-h] [-C DIRECTORY] [-l LOGLEVEL] [--no-banner] [command] ...

The Pigweed command line interface (CLI).


supported commands:
  doctor        Check that the environment is set up correctly for Pigweed.
  format        Check and fix formatting for source files.
  help          Display detailed information about pw commands.
  my_command    Do something to a connected device.

$ pw my_command -h

 ▒█████▄   █▓  ▄███▒  ▒█    ▒█ ░▓████▒ ░▓████▒ ▒▓████▄
  ▒█░  █░ ░█▒ ██▒ ▀█▒ ▒█░ █ ▒█  ▒█   ▀  ▒█   ▀  ▒█  ▀█▌
  ▒█▄▄▄█░ ░█▒ █▓░ ▄▄░ ▒█░ █ ▒█  ▒███    ▒███    ░█   █▌
  ▒█▀     ░█░ ▓█   █▓ ░█░ █ ▒█  ▒█   ▄  ▒█   ▄  ░█  ▄█▌
  ▒█      ░█░ ░▓███▀   ▒█▓▀▓█░ ░▓████▒ ░▓████▒ ▒▓████▀

usage: pw my_command [-h] [--device DEVICE]

Do something to a connected device.

optional arguments:
  -h, --help       show this help message and exit
  --device DEVICE  Set which device to target

Branding Pigweed’s tooling

An important part of starting a new project is picking a name, and in the case of Pigweed, designing a banner for the project. Pigweed supports configuring the banners by setting environment variables:

  • PW_BRANDING_BANNER - Absolute path to a filename containing a banner to display when running the pw commands. See the example below.

  • PW_BRANDING_BANNER_COLOR - Color of the banner. Possible values include: red, bold_red, yellow, bold_yellow, green, bold_green, blue, cyan, magenta, bold_white, black_on_white. See pw_cli.colors for details.

The below example shows how to manually change the branding at the command line. However, these environment variables should be set in the project root’s before delegating to Pigweed’s upstream

$ cat foo-banner.txt

 ▒██████  ░▓██▓░  ░▓██▓░
  ▒█░    ▒█   ▒█ ▒█   ▒█
  ▒█▄▄▄▄ ▒█ █ ▒█ ▒█ █ ▒█
  ▒█▀    ▒█   ▒█ ▒█   ▒█
  ▒█      ░▓██▓░  ░▓██▓░

$ export PW_BRANDING_BANNER="$(pwd)/foo-banner.txt"
$ export PW_BRANDING_BANNER_COLOR="bold_red"
$ pw logdemo

 ▒██████  ░▓██▓░  ░▓██▓░
  ▒█░    ▒█   ▒█ ▒█   ▒█
  ▒█▄▄▄▄ ▒█ █ ▒█ ▒█ █ ▒█
  ▒█▀    ▒█   ▒█ ▒█   ▒█
  ▒█      ░▓██▓░  ░▓██▓░

20200610 12:03:44 CRT This is a critical message
20200610 12:03:44 ERR There was an error on our last operation
20200610 12:03:44 WRN Looks like something is amiss; consider investigating
20200610 12:03:44 INF The operation went as expected
20200610 12:03:44 OUT Standard output of subprocess

The branding is not purely visual; it serves to make it clear which project an engineer is working with.

Making the ASCII / ANSI art

The most direct way to make the ASCII art is to create it with a text editor. However, there are some tools to make the process faster and easier.

  • Patorjk’s ASCII art generator - A great starting place, since you can copy and paste straight from the browser into a file, and then point PW_BRANDING_BANNER at it. Most of the fonts use normal ASCII characters; and fonts with extended ASCII characters use the Unicode versions of them (needed for modern terminals).

  • Online ANSII Edit by Andy Herbert - Browser based editor that can export to mixed UTF-8 and ANSII color. It’s also open source. What’s nice about this editor is that you can create a multi-color banner, and save it with the File –> Export as ANSi (UTF-8) option, and use it directly as a Pigweed banner. One caveat is that the editor uses UTF-8 box drawing characters, which don’t work well with all terminals. However, the box drawing characters look so slick on terminals that support them that we feel this is a worthwhile tradeoff.

There are other options, but these require additional work to put into Pigweed since they only export in the traditional ANS or ICE formats. The old ANS formats do not have a converter (contributions welcome!). Here are some of the options as of mid-2020:

  • Playscii - Actively maintained.

  • Moebius - Actively maintained.

  • SyncDraw - Actively maintained, in 2020, in a CVS repository.

  • PabloDraw - Works on most desktop machines thanks to being written in .NET. Not maintained, but works well. Has an impresive brush system for organic style drawing.

  • TheDraw - One of the most popular ANSI art editors back in the 90s. Requires DOSBox to run on modern machines, but otherwise works. It has some of the most impressive capabilities, including supporting full-color multi-character fonts.

Future branding improvements

Branding the pw tool is a great start, but more changes are planned:

  • Supporting branding the bootstrap/activate banner, which for technical reasons is not the same code as the banner printing from the Python tooling. These will use the same PW_BRANDING_BANNER and PW_BRANDING_BANNER_COLOR environment variables.

  • Supporting renaming the pw command to something project specific, like foo in this case.

  • Re-coloring the log headers from the pw tool.