let

Arithmetic assignment

$ let "x = 5 + 3"

$ let "count++"

$ let "a = 1" "b = 2" "c = a + b"

$ let "5 > 3"

$ let "result = 10 % 3"

let expression...

let is a Bash built-in for arithmetic evaluation. It performs integer math and comparisons.
The command sets exit status based on expression result. Zero result returns exit code 1.
let evaluates arithmetic.

EXPRESSION

Arithmetic expression(s).

+, -, *, /, %, ** (power)

++, -- (increment/decrement)

==, !=, <, >, <=, >=

&&, ||, !

Bash built-in. Integer only. Use (( )) as alternative. Returns 1 if result is 0.

let is a Bash built-in command for arithmetic evaluation, similar to expr but more powerful.

bash(1), expr(1), bc(1)