You didn't miss understand -nc. You missed the -O option where that expects the next argument to be the output file retrieved from the URL.
On Tue, Nov 18, 2014 at 10:11 AM, John Jason Jordan <[email protected]> wrote: > 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? > _______________________________________________ > PLUG mailing list > [email protected] > http://lists.pdxlinux.org/mailman/listinfo/plug > _______________________________________________ PLUG mailing list [email protected] http://lists.pdxlinux.org/mailman/listinfo/plug
