Disclaimer: I don't have enough inside knowledge to answer your real question, nor do I have anything to prove my following notion.

What could also be the case is that msg.exe does its own command line argument parsing. On my machine (Windows XP, Dutch) I get this:

C:\>msg /?
Een bericht naar de gebruiker sturen.

MSG {gebruikersnaam | sessiennaam | sessie-ID | @bestandsnaam | *}
    [/SERVER:servernaam] [/TIME:seconds] [/V] [/W] [bericht]

[download]

Liberally translated, this says that msg.exe takes the following arguments:

  1. Either a user name, a session name, a session ID, a "@" + file name, or a "*"
  2. Optional /SERVER:, /TIME:, /V, and /W switches
  3. Optionally a message
I suspect that what happens here is that msg.exe looks at all arguments it gets, sees that there is a "/w" before the message1, and waits for user response.

1 Or, more precisely, that there is something that could be interpreted as a "/w" before the message, even though that wasn't the intended meaning.

In reply to Re: system() implementation on Windows (again) by muba
in thread system() implementation on Windows (again) by Anonymous Monk

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