shells vs command interpreters vs command line?
operating-system
Solution
On UNIX-like systems, such as Linux, there are many command interpreters available, such as `sh`, `csh`, `ksh` or `bash`. Each user can choose which to have as a default. The term `shell`, which originally designated the single command interpreter available, comes from the notion that the UNIX architecture is layered and is often depicted as a set of concentric spheres; the inner one, the one that is closest to the hardware, is the kernel, the outer one, which at the time provided the only interface available to the user, is the shell.
As other command interpreters became available they were all referred to as shells and it became an informal convention for them to have the `sh` character sequence in their name.
Problem
what is the different between shells and command interpreters and command line? I read in concepts of operating systems book this sentence: On systems with multiple command interpreters to choose from, the interpreters are know as shells. could someone explain what it means?