This was around 0.13 or so, when Linux was still distributed on two floppies. I did the first port of Julie Haugh's shadow password suite, and a couple of things required for that, including an m4 port (not the GNU m4, a different one), a tweak to the kernel to allow a /bin/login to not echo passwords, and sdbm (an ndbm-workalike).
The shadow password suite historically wasn't
well-integrated with Linux in the early days because Linus felt Linux should stay light-weight,
and he didn't consider the shadow password suite light enough.
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