[PLUG] Flashair and wget

[John Jason Jordan]

At the Clinic Wes composed a lovely command (that I converted to a
shell script) to download files from a Flashair SD+wifi card that lives
in a CPAP machine upstairs in my house. The connection is a bit wobbly
because the advertised range of the Flashair is 30 feet, and that is
about the distance from the machine to my laptop downstairs, plus there
is a floor in between. But it does work if I am patient. Here is the
command:

wget -qO - http://192.168.0.1/DATALOG | grep 'DATALOG.*fname' | sed
-e "s/^.*fname\"\:\"//" -e "s/\", \"fsize.*//" | while read line; do
wget "http://192.168.0.1/DATALOG/$line";done

The reason for the grep and filename search is that Toshiba, in its
alleged wisdom, decided to bury the files in the html rather than just
use a directory structure like ftp. 

But there is a problem: Every night the CPAP machine writes eight more
small files to the DATALOG folder, where the name of each file starts
with the date, e.g.:

20141116_235932_BRP.crc 		(from Sunday night)
20141117_235932_BRP.crc 		(from last night)

The normal behavior of wget is to re-download files already downloaded
and append .n to the additional copies, so running the script this
morning would result in the following files in the folder:

20141116_235932_BRP.crc 		(from Sunday night)
20141116_235932_BRP.crc.1 	(from Sunday night)
20141117_235932_BRP.crc 		(from last night)

After a while the folder where I store these files on my computer is
going to get horribly cluttered. I could add a line to the script to
delete all files ending in .1, but considering the time it takes for
the script to run (due to the poor connection) it would be far
preferable for wget not to download copies in the first place.
According to the man page adding -nc (no-clobber) is supposed to do
this. So I added -nc like this:

wget -qO -nc - http://192.168.0.1/DATALOG ...

When I ran the script it downloaded no new files, but created a file
'nc' of zero bytes. WTH? Clearly I have failed to grasp how the -nc
option is supposed to work. 

Are there any wget experts here who can lead me to the light?