bash actually has a "restricted" mode which is sort of like that. In restricted mode, the following are disallowed:

- Changing directories with cd.

- Setting or unsetting the values of SHELL, PATH, HISTFILE, ENV, or BASH_ENV.

- Specifying command names containing /.

- Importing function definitions from the shell environment at startup.

- Parsing the values of BASHOPTS and SHELLOPTS from the shell environment at startup.

... some other things mainly preventing you from escaping or disabling the restricted mode.

Does that work? I've never seen it used. It seems easy to escape.

The docs seem to suggest using alternate approaches.

> Modern systems provide more secure ways to implement a restricted environment, such as jails, zones, or containers.

	▲	SoftTalker an hour ago \| parent [-]
		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.