Windows [cmd.exe] command to display a messagebox with timeout?

Question

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How can I display a messagebox by typing a single Windows command, e.g. in the Run dialog from the Start menu, or in the [cmd.exe] command interpreter?

Answer 1

One way is to use apparently undocumented functionality, namely that [mshta.exe], the runtime engine for Windows .hta HTML applications, accepts a general URL as command line argument, including a javascript: protocol URL:

mshta "javascript:var sh=new ActiveXObject( 'WScript.Shell' ); sh.Popup( 'Message!', 10, 'Title!', 64 );close()"

            

This command can be issued in e.g. [cmd.exe]], or e.g. in the Run dialog from the Start menu, perhaps combined with the schtasks command to create a tea-timer…

The above messagebox times out after 10 seconds, but specifying a 0 second timeout means “don’t time out”, producing a more ordinary persistent messagebox.

For a simpler messagebox you can instead use the alert function provided by the MSHTA host.