Convert string into integer in bash script - “Leading Zero” number error

Question

In a text file, test.txt, I have the next information:

sl-gs5 desconnected Wed Oct 10 08:00:01 EDT 2012 1001

I want to extract the hour of

Answer 1

The leading 0 is leading to bash trying to interpret your number as an octal number, but octal numbers are 0-7, and 8 is thus an invalid token.

If I were you, I would add some logic to remove a leading 0, add one, and re-add the leading 0 if the result is < 10.