Kind Of Shell

There are many kind of shell in this world. Maybe if you an attacker you will think shell is one kind of tool to hijacked a site or other like C99, R57 and the famous one from Indonesia b374k shell. Here we talk not about cracker tool but we talk about shell in Linux than can help you interactive with your Linux OS.

From Book The Linux Programming inTerface

• Bourne shell (sh): This is the oldest of the widely used shells, and was written by Steve Bourne. It was the standard shell for Seventh Edition UNIX. The Bourne shell contains many of the features familiar in all shells: I/O redirection, pipelines, filename generation (globbing), variables, manipulation of environment variables, command substitution, background command execution, and functions. All later UNIX implementations include the Bourne shell in addition to any other shells they might provide.
• C shell (csh): This shell was written by Bill Joy at the University of California at Berkeley. The name derives from the resemblance of many of the flow-control constructs of this shell to those of the C programming language. The C shell provided several useful interactive features unavailable in the Bourne shell, including command history, command-line editing, job control, and aliases. The C shell was not backward compatible with the Bourne shell. Although the standard interactive shell on BSD was the C shell, shell scripts (described in a moment) were usually written for the Bourne shell, so as to be portable across all UNIX implementations.
• Korn shell (ksh): This shell was written as the successor to the Bourne shell by David Korn at AT&T Bell Laboratories. While maintaining backward compatibility with the Bourne shell, it also incorporated interactive features similar to those provided by the C shell.
• Bourne again shell (bash): This shell is the GNU project’s reimplementation of the Bourne shell. It supplies interactive features similar to those available
  in the C and Korn shells. The principal authors of bash are Brian Fox and Chet Ramey. Bash is probably the most widely used shell on Linux. (On Linux, the Bourne shell, sh, is actually provided by bash emulating sh as closely as possible.)