Arithmetic Expressions
The
let
command performs integer arithmetic.
bash
provides a way to substitute integer values
(for use as command arguments or in variables); base conversion is
also possible.
Expression |
Meaning |
---|---|
(( |
Use the value of the enclosed arithmetic expression. |
Operators
bash
uses arithmetic operators from the C
programming language; the following list is in decreasing order of
precedence. Use parentheses to override precedence.
Operator |
Meaning |
---|---|
|
Unary minus |
|
Logical negation; binary inversion (one’s complement) |
|
Multiplication; division; modulus (remainder) |
|
Addition; subtraction |
|
Bitwise left shift; bitwise right shift |
|
Less than or equal to; greater than or equal to |
|
Less than; greater than |
|
Equality; inequality (both evaluated left to right) |
|
Bitwise AND |
|
Bitwise exclusive OR |
|
Bitwise OR |
|
Logical AND |
|
Logical OR |
|
Assign value |
|
Reassign after addition/subtraction |
|
Reassign after multiplication/division/remainder |
|
Reassign after bitwise AND/XOR/OR |
|
Reassign after bitwise shift left/right |
Examples
See the let
built-in command for more
information and examples.
let "count=0" "i = i + 1"
Assign i and countlet "num % 2"; echo $?
Test for an even number
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