There’s no “the shell,” assuming you’re asking about the Unix/Linux shell. Besides the common sh and bash you can use any number of shells. Lots of people have

There’s no “the shell,” assuming you’re asking about the Unix/Linux shell. Besides the common sh and bash you can use any number of shells. Lots of people have reinvented the shell and done things differently. It’s just a program. https://en.wikipedia.org/wiki/Unix_shell https://en.wikipedia.org/wiki/Unix_shell