wiki.bash-hackers.org/syntax/ccmd/arithmetic_eval.markup

====== Arithmetic evaluation (command) ======

===== Synopsis =====
<code>
(( <EXPRESSION> ))
</code>

===== Description =====
This command evaluates the [[syntax:arith_expr | 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 [[syntax:arith_expr#arithmetic_expressions_and_return_codes | this section]].


The functionality basically is equivalent to what the [[commands:builtin:let | ''let'' builtin command]] does. The arithmetic evaluation compound command should be preferred.

===== Examples =====


===== Portability considerations =====

===== See also =====
  * Internal: [[syntax:arith_expr | arithmetic expressions]]
  * Internal: [[syntax:expansion:arith | arithmetic expansion]]
  * Internal: [[commands:builtin:let | The ''let'' builtin command]]