Questions tagged [devices]

devices refers to questions about the Unix/Linux device special files, normally these are under /dev. Do not use this tag for physical devices (for that use e.g. usb or pci).

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why does a device node need to be made in udev when you plug in a device into your computer?

Why does a device node need to be made in udev when you plug in a device into your computer? Why does a device node need to exist?
How To Linux's user avatar
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System not booting after resizing /dev/sda2 and creating a swap partition

Error Message: dev/sda2: The filesystem size (according to the super) is 31126889 blocks The physical size of the device is 29884416 blocks Either the superblock or the partition table is likely to ...
SatoruGojo's user avatar
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26 views

Changing keyboard backlight causes sound to stutter – why?

I'm on a Dell Vostro 16 laptop (running elementary OS 7.1 based on Ubuntu 22.04.3, kernel 6.5). The laptop has a backlit keyboard that can be controlled using /sys/class/leds. Specifically, to turn ...
m93a's user avatar
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what is the difference between a device node and a device file? [closed]

question, what is the difference between a device node and a device file? is there any difference or are they the same thing? or maybe is a device file a type of device node? can a device node be more ...
How To Linux's user avatar
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2 answers
55 views

Linux 6.7: /sys/class/graphics/fb0 is missing

What happened to this node/symlink? It used to be there for ages, linking to the primary display adapter, and I cannot find it any longer with Linux 6.7.4. I've not found anything relevant in the ...
Artem S. Tashkinov's user avatar
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22 views

What is the purpose of the symbolic device file named with the HCTL address in the bsg folder

"/dev/bsg – This folder is for Block Scsi Generic drivers." I'm not sure what that means. There are two symbolic device files named with HCTL addresses in that folder, but from what is ...
xnl2d's user avatar
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1 answer
31 views

What file is /dev/btrfs-control?

I can't find any explanation about this file in the official documentation, I just know from the official documentation in devices.txt that this file is: "234 = /dev/btrfs-control Btrfs control ...
xnl2d's user avatar
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-2 votes
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How to create a sound device

Are there for resources for how to create a sound output device in Unix? A software defined output that you could send audio to, instead of speakers or Bluetooth or the likes. I'm essentially looking ...
Fake51's user avatar
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1 vote
1 answer
64 views

What file is /dev/autofs?

I searched /dev/autofs from https://www.kernel.org/doc/Documentation/admin-guide/devices.txt I searched for /dev/autofs in and found that it is 10,235. I used debian and stat /dev/autofs shows 10,235 ...
xnl2d's user avatar
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Pseudo-terminals control each other, how to get the return display

The problem is: my pseudo-terminal is /dev/pts/0, the target pseudo-terminal is /dev/pts/4, and I'm trying to get the target pseudo-terminal to print text using the echo text > /dev/pts/4 command. ...
xnl2d's user avatar
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Why are the unit numbers changed when PCI cards are added or changed (Linux Zorin...)?

PCI card removal with nvidia processor Installation of a graphics card (AMD) in another PCI express slot. Moving another PCI card Reboot NO wifi... After some research, I discovered that the ...
6422languedoc's user avatar
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1 answer
19 views

Use libfido2 on macos to set PIN on usb security token

I have bought a FIDO-U2F/FIDO2 usb security token and managed to add it as passkey for github on my macOS (sonoma). It didn't work for another site and I suspect that it's because the key doesn't have ...
chmike's user avatar
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1 answer
50 views

Get /dev entry for USB on a Mac

I have never used a Mac before and have no idea what I'm doing. I need to run dd on a USB device to copy data off. I plug the device in, and it shows up in system_profiler SPUSBDataType. How do I ...
Nate's user avatar
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1 answer
23 views

Why does VPS with stock Debian contain cdrom device?

I recently set up a debian 12 VPS with a new hosting company. It has: /media/cdrom -> cdrom0/ /media/cdrom0/ And in /etc/fstab: /dev/sr0 /media/cdrom0 udf,iso9660 user,noauto 0 ...
lonix's user avatar
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2 answers
80 views

I messed /dev/tty ownership and permissions [closed]

I was flashing a Flipper Zero Wifi Dev Board and I needed to have /dev/ttyACM0 owned by dialout group... The thing is now I have tried to revert the stuff, making a chown root:tty /dev/tty*, and chmod ...
DaniWein's user avatar
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54 views

Udev rule randomly failing on boot

I have an embedded system with ubuntu running on it. Inside its /etc/udev/rules.d directory i put a file named 99-mydevice.rules: KERNEL=="video0", SUBSYSTEM=="video4linux", ...
Marco Montevechi Filho's user avatar
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0 answers
54 views

Why are /dev/sdX not persistent and we have to use udev rules? [duplicate]

Why are the /dev/sdX names not persistent and we have to use udev rules or something else? Why the name changes? Is it only the name and permissions or does something else change as well? Why?
Astora's user avatar
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106 views

Will a platform device with waiting for supplier eventually probe?

I have defined a platform device in the Device tree. The following shows the file tree walk for its folder. /sys/devices/platform/device /sys/devices/platform/device/uevent /sys/devices/platform/...
Bret Joseph's user avatar
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1 answer
76 views

Is there a way to permanently "assign" /dev/ names to removable USB devices

I have a GPS unit which attaches by a USB port to Raspberry Pi. Because of the "mysterious" (to me) way the Arch Linux system that powers the Pi assigns /dev/ filenames, I never know if I'm ...
Steve Cohen's user avatar
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152 views

How to read NAND OOB (including ECC) data in Linux?

I am working on an embedded Linux system (5.10.24), where there is a NAND FLASH as storage. The NAND FLASH supports internal ECC and has 128Bytes OOB. Its DS says if the ECC is enabled the last ...
wangt13's user avatar
  • 396
2 votes
1 answer
100 views

umount /chrootedpath /dev/pts after several chroot(s): target is busy

I've been doing several chrooted environments in parallel, each in separate folder (when the script with chroot exited I sometimes run another in same folder), and for a while it seemed fine. But now ...
Alex Martian's user avatar
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2 answers
57 views

Is there a kernel parameter to hide/disable disk at boot time?

I am looking to install a new linux distro in my computer and I'd like for it to not have access to other disks in my pc (e.g the disk where I have all my documents, other operating systems, etc.) ...
Juanjo's user avatar
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3 answers
134 views

Why can't I directly ls /dev/sda1

I have an external microSD card plugged into my machine via a USB stick. I believe it was auto-mounted because I can see $ ls /media/me 7538-3DFD I believe it is mounted to /dev/sda1 because I see $ ...
user1245262's user avatar
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37 views

Cannot start link in /dev with LD_PRELOAD and ffmpeg

I successfully start ffmpeg on my old webcam with: ssh my_host "LD_PRELOAD=/usr/lib/x86_64-linux-gnu/libv4l/v4l2convert.so ffmpeg -f video4linux2 -i /dev/video0 -f matroska -" | mplayer - -...
klpu39's user avatar
  • 11
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0 answers
145 views

HID events are received, but mouse input still not working

I'd like to understand what I'm missing between HID events and libinput. I have a device that is sending correct mouse events, recorded from hid-recorder: e.g. For a left-click: # ReportID: 11 / ...
Sam Bull's user avatar
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0 answers
26 views

Tool for monitoring kernel driver messages? What are the options?

I'm working on a kernel-level device driver that sends requests to an underlying piece of hardware. Those requests have a fixed length and a given layout (including multiple fields with encoded values,...
ismarlowe's user avatar
3 votes
1 answer
809 views

What's the reason to add a symlink to /dev directory with udev rules?

I understand that you can write custom udev rules to create a symlink in /dev directory. But what is the use of having a symlink in /dev? What is the symlink linking to? I know you can interact with ...
Dr. Chocolate's user avatar
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0 answers
153 views

Sometimes cannot boot because a disk is mounted under the wrong /dev number

Hopefully this is not a duplicate question, I have found some similar ones but none that exactly match. I have an Arch Linux installation dual booted alongside a Windows installation, both on ...
Jacob Garby's user avatar
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0 answers
108 views

Can an audio output priority list be defined?

Is it possible to set priorities for audio output devices, such that audio will be sent to the appropriate output, depending on what’s plugged in? (That is, hot pluggable: the priority list should be ...
Xophmeister's user avatar
0 votes
1 answer
135 views

dd not enough space

I have a drive that is about 1TB big. It is mostly free space. When you add up the size of all the partitions, it is less than 256GB. I have another drive that is 256GB. I would like to clone the data ...
user168226's user avatar
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0 answers
58 views

scsi timing out command, waited 300 seconds

I am booting rescue system on a server, which has defective HDD or controller. The kernel boot process times out with following messages: scsi timing out command, waited 300 seconds eventually it ...
Martin Vegter's user avatar
1 vote
0 answers
22 views

What happens behind the file system when moving the source of a loop drive into its mountpoint?

I moved the source of a loop drive into its mountpoint and umount it. Then the source disappeared. Note that after moving the source to its mountpoint (or other location), the source was shown as ...
PanJianhong's user avatar
4 votes
2 answers
168 views

Why does LVM not provide the function of recursive creation?

I tries to recursively create LVM on LVM but it seemed unable to provide this function. The way I did is like: Firstly, I created a physical volume and a volume group on a physical device by $ ...
PanJianhong's user avatar
1 vote
0 answers
37 views

Switch buttons on only the left-handed mouse (input devices)

I've got two Logitech M650 Mice hooked to by Debian 12 Gnome 44 Machine. One is a "Left-Handed" mouse. I would like to swap the buttons on just the left mouse so that I can use my index ...
gavstar's user avatar
  • 11
1 vote
1 answer
333 views

Which service creates /dev/fb0 node?

I want to update the console-setup.service to detect screen resolution using fbset -s and adjust console font size accordingly. For fbset, I need /dev/fb0 to be present, but I don't know which service ...
Tomasz Garbus's user avatar
0 votes
0 answers
343 views

Fingerprint doesn't work in linux (Pop!_OS 22.04 LTS)

I am trying to enable fingerprint, but when I run sudo fprintd-enroll it shows this Impossible to enroll: GDBus.Error:net.reactivated.Fprint.Error.NoSuchDevice: No devices available. can anyone help ...
Giorgi Tsignadze's user avatar
0 votes
1 answer
27 views

Are device nodes stored as files or just special entries in directories?

My question is related to the way device nodes are implemented in Linux. I know there are pseudo files systems like udev or devtmpfs available - in this case there is no real storage behind and the ...
mrn's user avatar
  • 149
0 votes
0 answers
47 views

Can I use POLL to determine when USB disconnected

I'm working on an old Linux 2.4 kernel and I'm trying to figure out how I can send a signal from the device driver to the application when the USB device has been disconnected. I've been reading my ...
Fratink's user avatar
  • 41
2 votes
0 answers
393 views

udev inside lxc container

I am running a privileged Debian LXC Container on Proxmox, and then running Docker inside that. I am attempting to run an Xserver in a Docker container with Sunshine to stream to a Moonlight client. I ...
Dennis George's user avatar
0 votes
1 answer
3k views

Docker Permissions issue accessing `/dev/dri` Device

I have a permissions problem. I am running Photoprism inside a Docker container on Ubuntu 22.04. I want to use Intel QuickSync hardware transcoding. To do this, the app needs to access the /dev/dri ...
Eddified's user avatar
  • 101
0 votes
0 answers
225 views

How to install and get RAID 0 to work on Rocky Linux 8.7 using AMD controller

Running this command I can see the RAID controllers for my motherboard in Rocky Linux 8.7 [root@richardserver ~]# lspci -nn|grep RAID 03:00.1 RAID bus controller [0104]: Advanced Micro Devices, Inc. [...
Rich007's user avatar
1 vote
0 answers
76 views

How to pass a character device to something expecting a named pipe

Is it possible to convert a special file corresponding to a character device into a pipe? Specifically if I had an embedded device connected to a linux system via USB, and the device could send/...
Peter Hull's user avatar
0 votes
1 answer
248 views

How to speed up sending event to /dev/input/eventX in Linux?

I am working on an embedded Linux system with kernel-5.10.24, and I want to send events to system by writing to /dev/input/eventX. With my testing of sendevent (sendevent.c), the event injecting is ...
wangt13's user avatar
  • 396
1 vote
1 answer
579 views

How to completely disable network interfaces in Ubuntu 16.04

On my Ubuntu 16.04 server, I need to disable the onboard NIC for troubleshooting before upgrading to 22.04. It's important that the entire NIC no longer shows up as a network controller in my device ...
Henry van Megen's user avatar
1 vote
1 answer
2k views

Can't disconnect nbd device

I made an .qcow2 image and mounted it as described here: https://bytefreaks.net/gnulinux/how-to-mount-a-qcow2-disk-image-that-does-not-contain-an-ubuntu-lvm-installation But I have a problem with the ...
MijatTomić's user avatar
0 votes
0 answers
271 views

How to determine which qdiscs a NIC can support?

I am currently trying to test out ETF qdisc scheduler. I am attempting to replace the current qdisc $ tc qdisc show dev em1 qdisc pfifo_fast 0: root refcnt 2 bands 3 priomap 1 2 2 2 1 2 0 0 1 1 1 1 1 ...
akastack's user avatar
3 votes
4 answers
284 views

Why can I still write to /dev/null even after /dev is mounted read-only?

I was surprised to discover that I can still write to /dev/null even after remounting /dev to be read-only. Here is a demonstration: # echo foo > /dev/null # echo foo > /dev/foo # mount -o ...
mpb's user avatar
  • 1,591
0 votes
0 answers
159 views

Should the "/dev" directory always be writable?

I have noticed that in a read-only kubernetes container, the /dev directory is still writable. I was wandering whatever the /dev directory should be writable by design? or is it possible to make it ...
Meir Tolpin's user avatar
0 votes
1 answer
413 views

How to change the major and minor number of a device file?

I am currently working with an Embedded Linux Board and need to use the serial port, which is represented by the device file /dev/ttyS0. Upon running the command ls -l, I observed that the major and ...
Joseph Pena's user avatar
0 votes
0 answers
34 views

What does it mean if /dev/null is not a character device? [duplicate]

I'm experiencing "weird" behavior on a Linux PC -- I don't know how to qualify the problem exactly, other than that it seems to have something to do with /dev/null, based on the error ...
StoneThrow's user avatar
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