Re: not sure about number comparison

[winnie hw]

Thanks David & Greg for the lessons.

regards.


On Sun, Feb 19, 2023 at 9:34 PM Greg Wooledge <greg@wooledge.org> wrote:

> On Sun, Feb 19, 2023 at 08:44:12AM +0800, winnie hw wrote:
> > 1. for number comparison, when to use "-ne" and when to use "!="?
>
> In addition to David's answers, bash also has the (( )) command, which
> is preferred for numeric comparisons.
>
> x=42
> if ((x < 5)); then
>     echo "too small"
> elif ((x > 20)); then
>     echo "too big"
> else
>     echo "just right"
> fi
>
> For bash scripts, many people advocate (( )) for numeric stuff, [[ ]] for
> string stuff, and not to use [ ] at all.  Following that advice will
> help make it clear which operations are being used.  They also offer
> the "prettiest" forms of code syntax for their respective operations
> (you can omit the quotes inside [[ ]] most of the time, and you can omit
> the quotes and the dollar signs inside (( )) most of the time).
>
>