Indeed...
Funny that does not work either.
I get a popup warning from firefox saying that myimage.gif|myimage2.gif could not be found.
maybe it works on windows only

pulpfist:
Firefox happily accepts any number of arguments I've tried without complaints. Strange that it won't work when you try it.

Will F:
Nope, neither escaping spaces or using $ mozilla-firefox "myimage.gif|myimage2.gif" works.
For some reason the results of `foo` seem to be handled in a slightly different way than just passing the results manually.