bash-hackers-wiki/docs/syntax/ccmd/arithmetic_eval.md

Arithmetic evaluation (command)

Synopsis

(( <EXPRESSION> ))

Description

This command evaluates the arithmetic expression <EXPRESSION>.

If the expression evaluates to 0 then the exit code of the expression is set to 1 (FALSE). If the expression evaluates to something else than 0, then the exit code of the expression is set to 0 (TRUE). For this return code mapping, please see this section.

The functionality basically is equivalent to what the let builtin command does. The arithmetic evaluation compound command should be preferred.

Examples

Portability considerations

See also

• Internal: arithmetic expressions
• Internal: arithmetic expansion
• Internal: The let builtin command