[plug] Bash "Processing" Script

[Jay Turner]

Jay said:
> > I wrote a script that appeared to be able to do all that however when I
> > called 'dd' (actually 'sleep 15' for testing)
> > the script would wait until 'sleep 15' finished before processing the
> > rest of the script which contained the dot printing portion.
> 
Bernd said:
> Notwithstanding that this won't actually tell you that dd is
> actually doing its thing:
> 
> 	( while : ; do sleep 3 ; echo -n "." ; done ) &
> 	dotter=$!
> 	dd if=/dev/the_ universe of=black_hole bs=1planet
> 	kill $dotter
> 
> A "better" way would be to check to see if the output is growing
> or if it's been updated every few seconds for a special file before
> producing the dot.

This is very similar to the squid function I posted about.

I believe this will do what I require.
Could you please explain what "while : ;" and "dotter=$!" are doing.

I have not encountered them before in my bash experience..

Thanks
Jay