RunCommand

RunCommand launches external programs during rendering. It can operate without an image, but the connected orange Input establishes order: the command launches after the connected node finishes rendering. The previously assumed Effect Mask is removed; BMD documents only one image input.

Frame Command applies to each rendered frame, Start Command to composition-render start and End Command to completion. These are different fields on different tabs. Do not equate Start with the first viewed frame or assume canceled-job behavior without a separate test.

Frame contains Hide, Wait, Command, Browse, Interactive, Number A–D and String. The supplied Start/End captures show Hide, Command and Browse; Wait, Interactive and substitution fields are not copied there. The reference preserves this interface distinction.

Wait on means waiting for the external application to exit. With it off, rendering continues without waiting. BMD states that a nonzero application result causes node failure; use Frame with Wait on for a controlled check of this behavior.

Frame documentation lists %a, %b, %t and %s: A/B, the current unpadded frame number and String text. %04t zero-pads the frame number to four positions. A similar %04f appears in the manual copying example but conflicts with its substitution list; the lessons use the explicitly documented %t.

Number C (%c) and Number D (%d) appear in the captured Inspector, although the manual substitution list is limited to A/B. Both controls are preserved with a clear evidence boundary: verify additional C/D formatting variants in your version.

The manual shows connecting after Saver so frame processing starts after saving finishes. Lesson graphs instead use Background → RunCommand → MediaOut: commands print fixed markers or return an exit status. They contain no copying, deletion, networking or file writes.

The executable, execution permissions, shell and stdout visibility depend on the OS and host. Lesson strings explicitly target Linux with GNU coreutils and absolute /usr/bin/echo, /usr/bin/true and /usr/bin/false paths. Windows/macOS require platform-specific adaptation.

An unchanged Viewer can be expected: RunCommand passes the connected image, while the program separately writes stdout or returns a status. Establish where your host exposes child-process output before testing. The web diagrams launch nothing; native RunCommand validation remains pending.