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| |
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 |
|---|---|
|
(( expr)) |
Use the value of the enclosed arithmetic expression. |
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 |
See the let built-in command for more information and examples.
let "count=0" "i = i + 1" Assign i and count let "num % 2"; echo $? Test for an even number
|  | |
| 7.3. Variables |  | 7.5. Command History |
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