Operators are used universally for setting, modifying, and comparing information as it passes around the shell.
The arithmetic operators allow mathematical calculations within the shell. Table A-1 describes the available arithmetic operators and shows how they are used with numbers.
Table A-1. Arithmetic operators
Operator |
Description |
Example |
Result |
---|---|---|---|
+ |
Add two numbers |
8+2 |
10 |
- |
Subtract one number from another Negate a number |
8–2 -8 |
6 -8 |
* |
Multiply two numbers |
8*2 |
16 |
/ |
Divide one number by another |
8/2 |
4 |
( ) |
Change calculation order and evaluate the enclosed first |
(8–6)*2 |
4 |
% |
Remainder of a division (modulus) |
8%3 |
2 |
When multiple arithmetic operators are combined in a single expression, MSH follows a precedence sequence for evaluation. The unary - operator (negate a number) will always be evaluated first, followed by multiply (*
), divide (/
), remainder (%
), add (+
), and subtract (-
). Parentheses ((expression)
) can be used to override the default operator-evaluation order.
Some arithmetic operators are overloaded for other types. In particular, when strings are used, the add and multiply operators act differently, as shown in Table A-2.
Table A-2. Arithmetic operators on strings
Operator |
Description |
Example |
Result |
---|---|---|---|
+ |
Concatenate two strings |
"a"+"b" |
"ab" |
* |
Repeat a string |
"c"*6 |
"cccccc" |
Assignment operators are used for defining and updating variable values. Although most composite operations are designed for ...
No credit card required