did the movie alien came from a book?

my friend saw in the movie alien that it came from a book

It came from a script...

There was a novel, but that came from the screenplay as I understand it.

its pretty safe to say that ALIEN did NOT come from a book. the film was scripted.

No, Dan Obannon adapted the script from certain influences such as The Thing and deep space, but the script is/was stand alone

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