I have added an answer to the FAQ.

I'm writing an application that will upload a local file to an sftp site, using WinSCP in conjunction with a script. However, I need the application to determine whether the upload has been successful. I've tried using the /log feature, but the log is overly detailed, and there is no obvious "script completed successfully" line. Ideally, I would add something like "echo 'File transfer complete'" to the end of my script, in conjunction with "option batch abort". This would only be written to the log if no errors had occurred. Could you add an "echo" command to the scripting language, or is there another way of providing feedback to another application?