Bourne Shell

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The Bourne Shell is a Unix shell upon which many shells are based; notably the Korn shell and Bourne Again SHell. (The other major tree of Unix shells descend from csh.)

Portable Shell Syntax is the scripting language syntax used by the System V Bourne shell. This syntax is compatible with the heirloom shell and is the syntax documented in most Unix books. Examples marked "Works with: Bourne Shell" should work in any of the Bourne-compatible shells.

A Bourne Shell script begins with a shebang (also known as a hashbang) like this, which tells the operating system to use the Bourne compatible shell interpreter:

#!/bin/sh

In 2009, Computerworld published an in-depth interview with Steve Bourne, The A-Z of Programming Languages: Bourne shell, or sh, which details the Bourne shell origins and design decisions.

Bugs

Bourne Shell and Heirloom Shell have problems with here documents. Here is one such problem. A substitution, inside a here document, inside backquotes, inside double quotes, does insert too many backslashes.

<lang bash>f() { cat <<! here $1 ! }

expr "`f string`"

Output from Bourne Shell: here \s\t\r\i\n\g
Correct output: here string</lang>

The workaround is to move the backquotes to an assignment.

<lang bash>f() { cat <<! here $1 ! }

var=`f string` expr "$var"

Output: here string</lang>