Re: [gentoo-amd64]corss compile 64bit on 32bit os

[Frank Peters]

On Thu, 17 Sep 2009 09:04:22 +0800
Xi Shen <davidshen84@××××××××××.com> wrote:

> i searched for a while, but cannot find the reference of that syntax.
> thanks a lot.
>

The ordinary syntax is ${string:position:length}, but in the ordinary case
the position is referenced from the LEFT end of the string.  To reference
from the RIGHT end of the string, as in the Gentoo script, a negative value
must be specified, but the negative value has to the result of an EXPRESSION,
hence the apparently unusual syntax.

Why?  See question E12 at this link:
http://www.faqs.org/faqs/unix-faq/shell/bash/

Just try it out.  Copy the following two lines to a file, give the file
executable permission, and create different symbolic links to it.
Then invoke the file using any of the symlinks.

#! /bin/bash
echo ${0:$[-2]}


Frank Peters