SparForte - Reference - Bourne Shell Word Expansions

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Bourne Shell Word Expansions

SparForte provides a subset of Bourne shell features for convenient use on the command line. Many new users are already familiar with the Bourne shell since it's the standard shell for Linux and FreeBSD. Also, the AdaScript syntax can be awkward to use for simple interactive commands. Where the Bourne standard conflicts with Ada SparForte always favors compatibility with Ada for the sake of the progressive development model.

Bourne shell arguments consist of groups of characters called "words". Each word is separated by spaces. SparForte does not implement the Bourne shell IFS variable.

Argument expansion is the process of performing substitutions on a Bourne shell word. Argument expansion occurs at run-time since it depends on the current working directory and the current value of variables.

Bourne shell expansions include:

Expansion	Before	After	Bush
Brace Expansion	a.{txt,.dat}	a.txt a.dat	not implemented
Tilde Expansion	~a/a.txt	/home/user/a.txt	OK
Variable Expansion	$HOME/a.txt	/home/usr/a.txt	OK
Command Substitution	`/bin/echo a.txt`	a.txt	Backquotes only
Arithmetic Expansion	$((2+2))	4	not implemented (use AdaScript parameters)
Pathname Expansion	a.*	a.txt a.dat	OK
Word Splitting	a\ word	"a word"	OK

There is no brace expansion, arithmetic expansion or process substitution. Some features support only a subset of the BASH features. For example, many of the special $ substitutions (${...}, $(...) and others) are not implemented. Otherwise, the basic Bourne shell features implemented in SparForte conform to the POSIX standard.