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Looking for an easy way to make a random number, i came across a web page that used the follow snip of code
echo $[ ( $RANDOM % $DIE_SIDES ) + 1 ]
What is the purpose of the $[. Googling did not reveal the answer I seek. Thanks
The
$[expression]construct is used for arithmetic;$[1+1], for example, returns 2. You can also say$((expression))orexpr 1 + 1. Theexprcommand version is old-school and should work in any shell, the$[expression]and$((expression))versions work in bash but I’m not sure if they’re covered by POSIX.Update: The
$[expression]form is a bash extension, the$((expression))form is specified for the POSIX shell.