class buildbot.steps.master.MasterShellCommand

Occasionally, it is useful to execute some task on the master, for example to create a directory, deploy a build result, or trigger some other centralized processing. This is possible, in a limited fashion, with the MasterShellCommand step.

This step operates similarly to a regular ShellCommand, but executes on the master, instead of the worker. To be clear, the enclosing Build object must still have a worker object, just as for any other step – only, in this step, the worker does not do anything.

In the following example, the step renames a tarball based on the day of the week.

from buildbot.plugins import steps

    command="mv widgetsoft-new.tar.gz widgetsoft-`date +%a`.tar.gz",


By default, this step passes a copy of the buildmaster’s environment variables to the subprocess. To pass an explicit environment instead, add an env={..} argument.

Environment variables constructed using the env argument support expansion so that if you just want to prepend /home/buildbot/bin to the PATH environment variable, you can do it by putting the value ${PATH} at the end of the value like in the example below. Variables that don’t exist on the master will be replaced by "".

from buildbot.plugins import steps

              command=["make", "www"],
              env={'PATH': ["/home/buildbot/bin",

Note that environment values must be strings (or lists that are turned into strings). In particular, numeric properties such as buildnumber must be substituted using Interpolate.


(optional) The directory from which the command will be run.


(optional) Signal to use to end the process if the step is interrupted.