bash question

[Bob Bell]

On Mon, Sep 23, 2002 at 11:44:05AM -0400, pll at lanminds.com <pll at lanminds.com> wrote:
> In a message dated: Mon, 23 Sep 2002 11:37:40 EDT
> "Thomas M. Albright" said:
> 
> >If the due date is greater than today, it outputs the message "Due in x
> >days." If the due date is less than today I get a message saying "You
> >are -x days past due." How can I convert the negative number into a
> >positive one in bash?
> 
> Well, assuming that 'x' is a variable which contains some whole 
> number representing the number of days in which 'it' is due, a 
> negative number representing an over-due 'it', then:
> 
> 	abs_x=`echo '$x' | sed s/-//`
> 
> ought to do it.

Alernatively, to stay within bash:

    neg_x=$(( -1 * x ))

or

    neg_x=$(( -x ))

or

    abs_x=$(( x < 0 ? -x : x ))

or

    abs_x=${x#-}

-- 
Bob Bell <bobbell at zk3.dec.com>
-------------------------------------------------------------------------
 "It's easy to solve the halting problem with a shotgun.   :-)"
   -- Larry Wall, creator of the Perl programming language