The Korn shell offers compatibility with the Bourne shell, while providing a more robust programming language and command interpreter. It also contains some features of the C shell. The major features of the Korn shell are:
Improved performance. Programs written in the Korn shell can run faster than similar programs written in the Bourne or C shells.
Bourne shell compatibility. Programs written for the Bourne shell can run under the Korn shell without modification.
Command-line editing. Instead of backspacing or retyping, commands can be edited in vi, emacs, or gmacs mode.
Command history. Commands are stored in a history file, which can then be modified and re-executed or just re-executed as is. The commands are saved, up to a user-specified limit, across multiple login sessions.
Enhanced I/O facilities. File descriptors and streams can be specified. Multiple files can be opened at the same time and read. Menus can be formatted and processed more easily.
Added data types and attributes. Variables can now have a type, as well as size and justification attributes.
Integer arithmetic support. Integer arithmetic can be performed in any base from two to thirty-six using variables and constants. A wide range of arithmetic operators is supported, including bitwise operators.
Arrays. One-dimensional and associative arrays can be used.
Improved string manipulation facilities. Substrings can be generated from the value of strings. Strings can be converted to upper or lower case.
Regular expressions. Better support of regular expressions in variable expansion and filename wildcards has been added.
Job control. The Korn shell job control feature is virtually the same as that of the C shell. Programs can be stopped, restarted, or moved to and from the background. Programs can be identified for kill with their job numbers.
Aliases. Programs, and Korn shell scripts, along with their options can be aliased to a single name.
New options and variables. These have been added to provide more control over environment customization.
Functions. Increases programmability by allowing code to be organized in smaller, more manageable units, similar to procedures in other languages. Functions also allow Korn shell programs to be stored in memory.
Enhanced directory navigation facilities. The previous directory, and home directory of any user can be referred to without using pathnames. Components of previous pathnames can be manipulated to generate new pathnames.
Enhanced debugging features. More robust diagnostic facilities have been provided, and functions can be traced separately.
Other miscellaneous features. New test operators, special variables, special commands, control commands, command-line options, and security features have also been added.
