Different Shells: which, when, why

• sh: the Bourne shell
  • developed by Steven Bourne at AT&T Bell Laboratories
  • most compact but also simplest shell
  • very good features for controlling input and output, but not well suited for an interactive user
  • good choice for writing shell scripts
  • default prompt is $

• csh: the C shell
  • developed by Bill Joy at the University of California
  • uses C type syntax
  • input/output implementation is worse than in Bourne shell which makes it not very good for programming.
  • has a job control allowing to reattach a job running in the background to the foreground.
  • provides a history feature allowing modification and repetition of previously executed commands
  • is suitable for interactive use.
  • the default prompt is %.

• ksh: the Korn shell
  • designed and developed by David G. Korn at AT&T Bell Laboratories
  • contains the best features of sh and csh, plus many new features of its own

• bash: the "bourne again" shell
  • originally written by Brian Fox of the Free Software Foundation, current developer and maintainer is Chet Ramey of Case Western Reserve University
  • contains a number of enhancements over bourne shell, both for interactive use and shell programming

• tcsh: the extended version of c shell
  • is suitable for interactive use
  • has the same features as c shell plus several additional user friendly features: use of arrows to repeat previous commands, the first letters can be completed into a unique file name by hitting the tabulator.

By default, U. of Waterloo user UNIX account is set up with c-shell, though other shells are also available. For interactive use you can choose any shell you wish. However, our labs will refer to c-shell (csh) and tc-shell (tcsh) respectively for interactive use. For programming purpose we will always use bourne shell (sh).