[SoftTalker]

I don't think I've ever seen it used. I think the idea was back in the day when you wanted to let a user have a shell login (because that's the only way you could use a shared computer) but wanted to confine them to a specific directory and prevent them running anything that wasn't in the pre-defined PATH that you set for them.

[tingletech]

You could also produce special purpose applications this way, say to provide access to the online library catalog, or a run a gopher client for use in a public terminal lab. Telnetting to a unix account running some sort of restricted shell was how these often worked.

A sibling comment I can't reply to asks if you can do with with unix permissions.

These were really intended for anonymous guest access, or at least often used for this purpose. You couldn't do the same things with the file permissions systems at the time.

[ryoshu]

Can't you do that with regular Unix permissions?