On Mon, Dec 03, 2012 at 04:12:25PM +0100, Tadziu Hoffmann wrote:
>
> > Actually all shells that I know of don't specify that
> > redirection take place at the end of the command line.
> > Witness:
> >
> > $ <<<$HOME cat
> > /home/mbianchi
> >
> > $ <<<$HOME >/tmp/i cat
> > $ cat /tmp/i
> > /home/mbianchi
>
> Hey, that's cool! I'd never even thought about it.
> So with regard to "proper" left-to-right order we can say
>
> <input command >output
Exactly. For instance
<infile >outfile while read a
do
process ${a}
done
Sidebar:
I always use ${a} instead of $a so they standout more in the scripts,
for readability.
Also usages like ${a:-defaultvalue} are then not as big of a surprise to
novice readers of my shell code. It's a shell variable with with "benefits".
I wonder sometimes if anyone really understands _all_ of bash(1) .
I know I don't. Heck, I never understood all of ksh .
I'll claim that understood all of sh back in 1985 or so.
You know, the original sh had a way to do 1 "here document" at the end of a
shell script?
:
cat >outfile
content
more content
:
in a shell script file would cat the content, down to the end of the file,
into outfile just as if you were typing it at a terminal!
I think the <<EOF ... EOF syntax was introduced by Steve Bourne and/or John
Mashey back in the before times.
--
Mike Bianchi
Foveal Systems
973 822-2085
mbian...@foveal.com
http://www.AutoAuditorium.com
http://www.FovealMounts.com
