Muster custom actions can be spawned by the Dispatcher or the Render clients, depending if they are jobs based or chunk based.

In both scenarios, you can use inline Python execution to pass custom arguments to custom actions as well as to environmental variables values configured either on a template basis or as a job override.

Be aware also that the syntax of custom actions uses the backslash (\) as an escape character, so you may need to escape special characters used to build the command lines like:

• ; ⇒ \;
• = ⇒ \=
• % ⇒ \%
• > ⇒ \>
• < ⇒ \<
• : ⇒ \:
• / ⇒ \/
• \ ⇒ \\
  

A sample code that spawn the Windows shell and execute a command follows:

C:\\Windows\\system32\\cmd.exe /c echo Hello! 

As introduced before, custom inline Python may be used. Muster automatically pass a job and a chunk object to the Python context. You can use them to build more complicated strings.

C:\\Windows\\system32\\cmd.exe /c echo job id: <%=job.getJobId()%> 

You can use the special <%= to automatically print a value. If you need to construct more complex expression, you can pass back the output using muster.expressionPrint() function:

C:\\Windows\\system32\\cmd.exe /c echo job id: <%muster.expressionPrint(str(job.getJobId()))%> 

Also pay particular attention when using inline Python either for actions or environmental variables. While the job object is always available, the chunk object is available only on chunks actions, but the environment may be shared for both scenarios.

So you can define a custom environmental variable using inline python in such way:

MYCHUNKID=<%if chunk not None: muster.expressionPrint(str(chunk.getChunkId()))%>

Also, if you activate on the Dispatcher and/or the Renderclient to export the Muster custom environment, you'll find the following environmental variables defined, either in a job execution context, or a custom action execution context:

MUSTER_JOB_NAME
MUSTER_SUBMISSION_TIME
MUSTER_PACKET_TYPE
MUSTER_TASKS_MASK
MUSTER_ENGINE
MUSTER_PRIORITY
MUSTER_INSTANCES_WORKING
MUSTER_MAX_INSTANCES
MUSTER_IS_PAUSED
MUSTER_END_TIME
MUSTER_START_TIME
MUSTER_STATUS
MUSTER_PROGRESS
MUSTER_SUBMITTER
MUSTER_NAME
MUSTER_JOB_PORJECT
MUSTER_JOB_DEPARTMENT
MUSTER_JOB_CAMERA
MUSTER_JOB_SHOT
MUSTER_JOB_SEQUENCE
MUSTER_JOB_ID
MUSTER_PACKET_SIZE
MUSTER_POOL
MUSTER_EXCLUDED_POOL
MUSTER_EXITCODES_ERROR_CHECK_TYPE
MUSTER_LOGS_ERROR_CHECK_TYPE
MUSTER_PARENT_ID
MUSTER_JOB_TYPE
MUSTER_DEPEND_ID
MUSTER_DEPEND_MODE
MUSTER_DEPEND_LINK_MODE
MUSTER_REQUEUED
MUSTER_IS_LOCKED
MUSTER_IS_ARCHIVED

also you get a MUSTER_PARAMETERS_* for each attribute inside the job

You can query those values, directly inside your action code, using getenv or whatever command your script/language supports.