I've messed with this before trying to troubleshoot USB cams. It's highly dependent on the USB hardware. Not all USB devices implement "low power" mode.
Your best shot is to get a good USB 4 port hub - not a crappy one - a good one and the good ones Implement power control and can cut power to a USB device if you command them to. I went through several different USB hubs experimenting with this and ultimately gave it up as a waste of time. Depending on the hardware there can be side effects. Such as the entire USB bus freezing up and it won't even Come back with a warm boot of the computer. USB put the BS in peripheral interconnections. Ted -----Original Message----- From: PLUG <plug-boun...@lists.pdxlinux.org> On Behalf Of Vince Winter Sent: Monday, January 22, 2024 1:58 PM To: Portland Linux/Unix Group <plug@lists.pdxlinux.org> Subject: [PLUG] How to script USB device detection I will need to test but this may work. On Mon, Jan 22, 2024, 12:50 PM Tomas Kuchta <tomas.kuchta.li...@gmail.com> wrote: > Correction: recent kernels > 2.6 do not have ..../power/level --> use > .../power/control > > Or something like: > echo 1.4 /sys/bus/usb/drivers/usb/unbind > > -T > > On Mon, Jan 22, 2024, 15:42 Tomas Kuchta > <tomas.kuchta.li...@gmail.com> > wrote: > > > While not answering your question - this may solve your problem... > > > > You can cut power to usb device by something like this: > > > > echo suspend > /sys/bus/usb/devices/usb1/power/level > > > > That way, you could just make sure that nothing draws power > > regardless of plugged in or not. It could save you from unplugging > > stuff manually based on some message. > > > > Hope it helps, > > Tomas > > > > On Mon, Jan 22, 2024, 15:12 Vince Winter > > <thine.technoc...@gmail.com> > > wrote: > > > >> We are running power testing and we need to make sure their isn't > >> USB device plugged in it adds to the total system power by having > >> the USB > port > >> activate. > >> > >> I am trying to do a automated is USB plugged. > >> > >> We are using multiple generations of systems that are regularly > >> reinstalled. > >> > >> > >> On Mon, Jan 22, 2024, 9:42 AM Russell Senior > >> <russ...@personaltelco.net > > > >> wrote: > >> > >> > I don't quite understand. You are looking for a specific device? > >> > How > do > >> you > >> > identify the device? > >> > > >> > On Mon, Jan 22, 2024 at 9:35 AM Vince Winter < > >> thine.technoc...@gmail.com> > >> > wrote: > >> > > >> > > I need if USB device is plugged to not to continue the rest of > >> > > the > >> script > >> > > across multiple devices. I can't change every device and I am > >> > > trying > >> to > >> > > eliminate humans looking at which devices are plugged in. > >> > > > >> > > I do conceded that many laptop cameras are USB and Bluetooth > generally > >> > runs > >> > > on the USB bus. > >> > > > >> > > I have yet to find a good answer to this myself. > >> > > > >> > > On Fri, Jan 19, 2024, 3:54 PM Russell Senior < > >> russ...@personaltelco.net> > >> > > wrote: > >> > > > >> > > > Two things I will mention: lsusb and udev rules. > >> > > > > >> > > > I have a set of udev rules that match ttyusb devices by path > >> > > > (they > >> > don't > >> > > > implement serial numbers, which would be better) and give > >> > > > them a consistently named symlink. I use /dev/ttyRn, where n > >> > > > is a whole > >> > number. > >> > > > That means no matter what order they are enumerated in, I can > >> > > > find > >> the > >> > > > device. > >> > > > > >> > > > I don't know if that helps with your problem or not, but I > >> > > > have > >> found > >> > > them > >> > > > to be useful in adjacent problems. > >> > > > > >> > > > -- > >> > > > Russell > >> > > > > >> > > > On Fri, Jan 19, 2024, 15:17 Vince Winter < > >> thine.technoc...@gmail.com> > >> > > > wrote: > >> > > > > >> > > > > Hello, > >> > > > > > >> > > > > I am trying to write a bash script to detect if USB device > >> > > > > is > >> plugged > >> > > > into > >> > > > > a device and post a message with a device name that is > >> > > > > plugged > to > >> > > stdout. > >> > > > > > >> > > > > Complications are USB webcams, USB controllers, and this is > going > >> to > >> > be > >> > > > > used on large number of systems, so I can't customize to > >> > > > > each > >> system. > >> > > > > > >> > > > > >> > > > >> > > >> > > >
