Using bash "double paren" arithmetic expansion, math fails with leading zero I have a simple script that deals with hours and minutes. If I want to calculate number of minutes since midnight having a string s `hh:mm` I tried splitting string then doing `hh * 60 + mm` My problem is, while $ (( tot = 12 * 60 + 30 )) $ echo $tot 750 instead $ (( tot = 09 * 60 + 30 )) bash: ((: tot = 09: value too great for base (error token is "09") As far as I understand string `09` is not to be intended as a base 10 number. Is there a better way than simply removing leading zeros in string?

h=09; m=30;(( tot = 10#$h * 60 + 10#$m )); echo $tot


The number before the `#` is the radix (or base)
The number after the `#` must be valid for the radix
The output is always decimal
You can use a radix of _2 thru 64_ (in GNU bash 4.1.5)

Note that Bash requires a leading minus sign to come before the `10#`, so if your number has one, adding the `10#` prefix directly won't work.

As noted by _enzoyib_ , the old alternative of `$[expression]` is deprecated, so it is better to use the POSIX compliant `$((expr))`


$(( 2#1)) == 1
$((16#F)) == 15
$((36#Z)) == 35


I'm not sure which 'digits' are used after `Z`