Also, you can check the original sh by Stephen R. Bourne (Bell Labs, [1]). Or th...

Also, you can check the original sh by Stephen R. Bourne (Bell Labs, [1]). Or the original csh by Bill Joy (BSD, [2]). In Github there is a huge repository with a collage of Unix History, where is possible to check how shells have been evolved ([3]).

[1] https://github.com/dspinellis/unix-history-repo/tree/Bell-Re...

[2] https://github.com/dspinellis/unix-history-repo/tree/BSD-2-S...

[3] https://github.com/dspinellis/unix-history-repo