At Mon, 13 Apr 2026 09:27:25 -0500 [email protected] wrote:
> > On Sun 12 Apr 2026 at 16:40:36 (-0500), Gregory Forster wrote: > > I guess I was expecting recognition like when USB flash drives, hard > > drives, my voice recorder, my cell phone are connected, > > All those devices probably have some mass storage onboard, so if > you're running a DE or an automounter, you may see some effect, > like drawing an icon on the screen. > More formally, what is going in is that the graphical file manager (eg the Linux equivelant of MS-Windows' "Windows Explorer" or MacOS's "Finder") is displaying an icon for a "file system". Flash drives and external hard drives almost always have a factory installed [empty] file system and smart phones have an internal file system where the phones operating system resides. An optical drive *by itself* never has a file system. Only when a disk is inserted is there the *possibility* of a file system. Generally speaking audio CDs don't have a "real" file system, just a collection of audio tracks (sort of like partitions containing "raw data"). Movie disks do have a file system, but it won't be flagged as a "data" disk and the graphical file manager might not bother with an icon. If you have an audio or movie viewer application installed, these apps might "recognize" these disks as a playable disk, but the graphical file manager might not show anything -- some do and some don't and it might be a configuration option. > > So, I tried it again. No, it wasn't recognized, but it seems to work. > > If it wasn't recognised, it wouldn't work. Yes, it was recognised, but > there was as little reason to disturb the user as there is when the > system recognises all the builtin devices shortly after booting up. > > To convince yourself, type: > > $ udevadm monitor -u -p -s block/disk > monitor will print the received events for: > UDEV - the event which udev sends out after rule processing > > Then plug in the device. You'll get some paragraphs from udev like: > > UDEV [2685.710126] add > /devices/pci0000:00/0000:00:14.0/usb2/2-1/2-1:1.0/host6/target6:0:0/6:0:0:0/block/sr1 > (block) > ACTIONd > > DEVPATH=/devices/pci0000:00/0000:00:14.0/usb2/2-1/2-1:1.0/host6/target6:0:0/6:0:0:0/block/sr1 > SUBSYSTEM=block > DEVNAME=/dev/sr1 > [ ⦠] > > and, instead: > > [ ⦠] > ACTION=remove > [ ⦠] > > when you unplug it. > > You can read what reacts to these events in /usr/lib/udev/rules.d/, > and write your own versions in /etc/udev/rules.d/, the two directories > being merged numerically to determine the order of running the rules > with each event. > > You can capture more events with just udevadm monitor -u -p > For example, type that line and then unplug your mouse or keyboard > momentarily (switch it off and on if wireless). > > Happy hacking. > > Cheers, > David. > > > -- Robert Heller -- Cell: 413-658-7953 GV: 978-633-5364 Deepwoods Software -- Custom Software Services http://www.deepsoft.com/ -- Linux Administration Services [email protected] -- Webhosting Services
