Arithmetic ExpansionArithmetic expansion provides a
powerful tool for performing arithmetic operations
in scripts. Translating a string into a numerical
expression is relatively straightforward using
backticks, double parentheses, or let. Variations - Arithmetic expansion with backticks (often used in
conjunction with expr)
z=`expr $z + 3` # 'expr' does the expansion. |
- Arithmetic expansion with double parentheses, and using let
The use of backticks in arithmetic
expansion has been superseded by double parentheses
$((...)) or the very
convenient let construction.
z=$(($z+3))
# $((EXPRESSION)) is arithmetic expansion. # Not to be confused with
# command substitution.
let z=z+3
let "z += 3" #If quotes, then spaces and special operators allowed.
# 'let' is actually arithmetic evaluation, rather than expansion. |
All the above are equivalent. You may use whichever one
"rings your chimes".
Examples of arithmetic expansion in scripts:
Example 12-6 Example 10-14 Example 26-1 Example 26-5 Example A-18
|
