Re: udev rules for webcam
On Fri, Nov 07, 2014 at 03:20:20PM -0500, Kevin Cummings wrote:
> On 11/06/2014 06:53 PM, Tom Horsley wrote:
> > On Thu, 6 Nov 2014 18:47:23 -0500
> > Fred Smith wrote:
> >
> >> not finding anything on that, I hit on writing a udev rule for the
> >> USB device to make sure it appeared as a predictable /dev/video.
>
> Did you try looking in /dev/v4l? My laptop builtin webcam leaves
> entries in there. The v4l directory has 2 sub-directories: by-id and
> by-path which contain entries for my webcam.
Hi Kev!
Yes, late yesterday I learned enough about udev to find the files
there, so I've modified my script to use those files to figure out
which /dev entry is the webcam I'm interested in. I suppose I could
use those files directly, too, and save a bit of computation.
an excerpt from the script that operates the camera:
# figure out which /dev/video entry is the camera we want.
foo=`ls -l --dereference-command-line-symlink-to-dir
/dev/v4l/by-id/usb-046d_0825*`
devnode=`echo $foo | sed -e "s;^.*> \.\./\.\./;;"`
# then snap it
${progdir}/fswebcam --png 9 -d /dev/${devnode} -r 800x600 -F 2 --save
${day}/img-%Y%m%d-%H%M%S.png
--
Fred Smith -- fre...@fcshome.stoneham.ma.us -
The Lord detests the way of the wicked
but he loves those who pursue righteousness.
- Proverbs 15:9 (niv) -
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Re: udev rules for webcam
On 11/06/2014 06:53 PM, Tom Horsley wrote: > On Thu, 6 Nov 2014 18:47:23 -0500 > Fred Smith wrote: > >> not finding anything on that, I hit on writing a udev rule for the >> USB device to make sure it appeared as a predictable /dev/video. Did you try looking in /dev/v4l? My laptop builtin webcam leaves entries in there. The v4l directory has 2 sub-directories: by-id and by-path which contain entries for my webcam. > I did something similar to recognize my 3D printer when I plug it > in, and it was quite challenging to make all my code work > because systemd runs things in magic "cgroups" that get killed > quickly and have limited permissions. I eventually got all the > complex stuff I wanted to do working. The full story is here: > > http://home.comcast.net/~tomhorsley/hardware/solidoodle/solidoodle-udev.html > -- Kevin J. Cummings kjch...@verizon.net cummi...@kjchome.homeip.net cummi...@kjc386.framingham.ma.us Registered Linux User #1232 (http://www.linuxcounter.net/) -- users mailing list users@lists.fedoraproject.org To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Fedora Code of Conduct: http://fedoraproject.org/code-of-conduct Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines Have a question? Ask away: http://ask.fedoraproject.org
Re: udev rules for webcam
On Thu, 6 Nov 2014 18:47:23 -0500 Fred Smith wrote: > not finding anything on that, I hit on writing a udev rule for the > USB device to make sure it appeared as a predictable /dev/video. I did something similar to recognize my 3D printer when I plug it in, and it was quite challenging to make all my code work because systemd runs things in magic "cgroups" that get killed quickly and have limited permissions. I eventually got all the complex stuff I wanted to do working. The full story is here: http://home.comcast.net/~tomhorsley/hardware/solidoodle/solidoodle-udev.html -- users mailing list users@lists.fedoraproject.org To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Fedora Code of Conduct: http://fedoraproject.org/code-of-conduct Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines Have a question? Ask away: http://ask.fedoraproject.org
