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Buck2 Consoles

Buck2 offers several console types for build-like commands (e.g. build, install, test, etc.). The console is always written to stderr.

The console can be specified via the --console flag, or the BUCK_CONSOLE env variable. The default console type is auto. Supported --console types:

  • auto - Default console type. Auto defaults to the superconsole if the stderr is a TTY. Otherwise will uses simple console
  • simple - Build a simpleconsole with TTY, if TTY is supported by the OS. See Simpleconsole
  • simplenotty - Build a simpleconsole without TTY. See Simpleconsole
  • simpletty - Build a simpleconsole with TTY. See Simpleconsole
  • super - Build a superconsole regardless of whether stderr is a TTY. See Superconsole
  • none - See No console

If simplenotty or none are specified, or if TTY is not supported by the OS, then we strip out any color within the error messages.

All console options will output the build result, whether succeeded or not, to stdout. Note that action execution stderr is hidden if the build succeeded.

The simple and superconsole will also print metadata about the build itself, such as the Buck2 UUID, the percentage of cache hits, and the number of action commands ran. In addition, they will print the event spans detected within the build.


The simpleconsole prints the stdout/stderr messages and event spans, line by line. There is no resource usage telemetry emitted.


Simpleconsole running a build


The superconsole uses the superconsole library to provide an interactive console which shows the event spans going on within Buck2.


Superconsole running a build


The superconsole also provides several toggles to inspect ongoing Buck2 telemetry.

To see what's available you can press ? or h. This will work as long as stdin is a TTY, which will be true most of the time if you're not piping anything into Buck2. To disable to allow alternate use of stdin, or for follow up pasted commands to not get swallowed, you can set the BUCK_NO_INTERACTIVE_CONSOLE environment variable, or use the flag --no-interactive-console.

We support the following toggles:

  • c - toggle commands (shown in superconsole by default)
  • d - toggle DICE key states
  • e - toggle debugging events, such as spans and instant event counts
  • 2 - toggle two lines mode when showing events
  • r - toggle detailed remote execution info, such as uploads, downloads, and action cache calls
  • i - toggle I/O counters
  • p - display target configurations
  • + - show more lines
  • - - show fewer lines
  • h - show help

Note: Not available yet for Windows

No console

When specifying the none console type, Buck2 will only print if the build succeeded, or the error if the build failed.