Question

I wrote a bash script in that i had a Value=09
and when I used $((Value)) an error occurred:

09: value too great for base (error token is “09”)

then I made a new bash file just with this line:

$((09))

and this had error again. I changed my way for that program but this question remained for me: Why? Whats wrong? Just 08 and 09 have this problem.

Answer 1

You can specify the base in bash. To force base 10:

Value=09
echo $((10#$Value * 2))  # ==> 18

From the bash manual:

Constants with a leading 0 are interpreted as octal numbers. A leading ‘0x’ or ‘0X’ denotes hexadecimal. Otherwise, numbers take the form [base#]n, where base is a decimal number between 2 and 64 representing the arithmetic base, and n is a number in that base. If base# is omitted, then base 10 is used.