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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Permanently grant permission to /dev/snd for all users?

After reboot ~$ arecord -l arecord: device_list:270: no soundcards found... and $ sudo arecord -l **** List of CAPTURE Hardware Devices **** Home directory not accessible: Permission denied card 0: ...
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My USB controller is not recognized (error 10) when I try to pass through it in a Windows 10 guest os with virt-manager and a QEMU-KVM vm

Actually I have a problem to fix. I want to attach two Kinect 2,one for each virtual machine with its own USB controller and GPU using virt-manager with a QEMU-KVM connection on Ubuntu 20.04. The ...
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1answer
34 views

Get major and minor from path's s

To get the major and minor device numbers a device node corresponds to, you use stat -c %T:%t <device file> To get the device number that a path is on, you use stat -c <%D|%d> <path>...
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“pkgProblem” error, can't install package

I have some problems while installing a package with apt (like gdb). Here is the error I am getting: The following packages contain unsatisfied dependencies : linux-headers-5.4.0-kali2-amd64 : ...
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device names in rfkill output do not match those from ip

The devices listed by the rfkill command are completely different from the device names listed by the ip command: > rfkill ID TYPE DEVICE SOFT HARD 0 wwan tpacpi_wwan_sw ...
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66 views

How does an open(at) syscall result in a file being written to disk?

I'm trying to learn as as much as I can about about the interplay between syscalls, the VFS, device driver handling and ultimately, having the end device do some operation. I thought I would look at a ...
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2answers
665 views

Reading from dev/urandom - system behaviour

When reading from dev/urandom, with say head or dd, it’s of course expected that the output is always random and different. How is this handled by UNIX at a low level? Is the file naturally truncated ...
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22 views

How do I troubleshoot my sd card reader?

My card reader doesn't seem to be able to recognise, let alone read, anything any more. lspci -v lists the device: 06:00.0 SD Host controller: O2 Micro, Inc. SD/MMC Card Reader Controller (rev 01) (...
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31 views

SATA disk drive behind Adaptec RAID 5405 can't be detected as block device

Due to shortage of free built-in SATA 3.0 plugs (6 totally) on my motherboard (Gigabyte 970A-DS3 rev.3) I've got an Adaptec RAID 5405 (3G SAS/SATA RAID) to move all "slow" SATA 1.0/2.0 ...
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67 views

cfdisk: cannot open /dev/sda

Background Info I am currently trying to build a Linux From Scratch (LFS) partition. This is my first attempt and I'm doing this to challenge myself, but I'm having trouble getting started. I'm using ...
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1answer
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How does the i2c subsystem match devices against drivers?

My understanding of this is fairly minimal so bear with me. From what I gather so far, the i2c subsystem on Linux identifies devices that are attached, and then matches them against loaded driver ...
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truncate linux kernel

firstly sorry for my English. I want to truncate kernel options like Bluetooth, mouse, keyboard etc.. except for my use. but how can I know that kernel options related to devices that I want to remove?...
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How to monitor read & write speed to specific device or mount point

How can I monitor the read & write speed to a specific device or mount point in Linux, for example /dev/sdc2 which is mounted to /mnt/data/? Would like to display the speed in MB/s for example and ...
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1answer
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ls says file exists, but file says no such file or directory

So when I were tweaking my laptop touchpad input, I came across this directory, and I found something weird. Maybe checking the command output is better than me trying to describe it: [root@T480-arch ...
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Where can I see the difference in those mounts?

# mount | grep 'rootvg-var\b' /dev/mapper/rootvg-var on /var type xfs (rw,relatime,seclabel,attr2,inode64,noquota) /dev/mapper/rootvg-var on /var/lib/docker/containers type xfs (rw,relatime,seclabel,...
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Create mountable device /dev/sd originated of a directory

From a directory how can we create mountable device /dev/sd... (as if usual partition) so simply a virtual device of a directory, by use of command line ? All must be by script/command line
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How to set /dev/ttyUSB device on a specific constant device number?

I use several Linux servers hosts, in which multiple serial-to-USB links are plugged in. They look like /dev/ttyUSBx devices, where x is a number starting from 0. Client devices are often rebooted or ...
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OpenStack machine mounting first volume as /dev/vdc

I have a virtual machine in an internal OpenStack environment. Today, it started misbehaving when a volume is removed and re-attached. In the following, the first two are correct, but the third is not:...
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Partition Table Entries is not in disk order

How bad is the effect of Partition Table Entries is not in disk order, will it just like nothing so won't need any fix ?
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1answer
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How are minor device numbers assigned for unnamed/non-device mounts (major number 0)?

I generally get how the whole major/minor device number thing works for a given device (though please correct me if I'm way off here), and how a major device number essentially relates to a class of ...
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evdev events not showing up in libinput or X11

Some background: I'm using a VEIKK A50 graphics tablet with a custom patched version of this driver to add button support. The tablet registers 3 evdev devices upon being plugged in - pen events come ...
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1answer
179 views

How to direct /dev/hidraw output to python application and not terminal

I have a USB barcode scanner and am running a python script that collects data from /dev/hidraw0 and inputs the data into a database. The issue is that every time the scanner collects a code it ...
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Is it possible to have SSH display an “active” banner, by running a script to generate the banner each time, rather than read a static file

The sshd_config banner directive reads a file, but I want it to run a script, and ideally personalize the banner to the user... is this possible with ssh, or is there a way I can create a device file ...
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1answer
72 views

Writing a simple misc char device driver with read and write operations

thank you for taking a look at this question. I am writing a simple misc char device with read and write operations. Please keep reading ... The following code prints the required text in TEXT only ...
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1answer
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Is it okay to create multiple instances of a device in centos?

I have a usecase to create multiple char devices of the same type. When I used the same major and minor number of the initially created device, the devices were duplicated and the functionality was ...
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Writing udev rule for 2 devices on same subsystem and same ATTRS{name}

I'm really new to udev. I've been using Debian with yoga book (with special kernel branch) for half year now. And the maintainer of this kernel (and the debian image) implemented the force feedback ...
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31 views

Why does “/dev/dsp” output with a 'Pulse-density modulation' (sort of)?

My understanding is that the input to /dev/dsp should be an 8-bit unsigned PCM signal/character stream. yet $ cat a.c #include <stdio.h> #include <math.h> int main(){ uint32_t t; ...
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33 views

How do I tell where a new device is mounted?

I have a usb GPS, I plug it in, and according to the indicator lights, it is working. Somewhere, on some device I should have a stream of GPS data comming in. How do I tell where that is? From dmesg: ...
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1answer
18 views

How can I map file IO from a file to an existing device?

As the title asks, how can I I map file IO from a file to an existing device? I am using a higher level programming language on one of these common SoC single board computers running Linux. This ...
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16 views

Why root user is not getting “Device or resource busy” response?

I am working with GSM modem and using /dev/ttyUSB2 device. Device is having proper rights: $ ls -alh /dev/ttyUSB2 crw-rw---- 1 root dialout 188, 2 May 25 19:44 /dev/ttyUSB2 I am in dialout group ...
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Bluetooth not getting recognized on newer kernels (works on 4.19)

I have windows 10 installed on my pc. I installed many linux distros including Ubuntu, Elementary OS, Pop os and debian in dual boot. Out of all of these, bluetooth worked only on debian. I checked ...
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326 views

systemd-shutdown[1]: Failed to finalize DM devices, ignoring

Each time I reboot my laptop, that's running Kubuntu 20.04, I see this message right before it reluctantly reboots: systemd-shutdown[1]: Failed to finalize DM devices, ignoring Also, rebooting takes ...
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25 views

Can I share a SCSI device with another machine over the network?

I have a SCSI Controller which is connected to a Tape changer/LTO Drive: # lsscsi [12:0:2:0] tape HP Ultrium 4-SCSI W61U /dev/st0 [12:0:2:1] mediumx TANDBERG StorageLoader ...
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27 views

Kernel boots with NULL pointer exception for a device

My goal is to use RTDM SPI driver with Raspberry Pi 3B. I have built Xenomai 3.0.8 on Linux 4.9.80 with Real-time SPI support enabled as a module. Afterwards I have edited device-tree file (bcm2710-...
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1answer
39 views

How can I create a pseudo-file that gets its content from a command everytime it is read

I want to create something file-like (that can be read like a common file), which everytime it is read, it gets its output from a command. For instance, if I do echo $RANDOM > test, then I can ...
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37 views

Can I run ADB/FASTBOOT command from Android to Android

I was curious to ask that can I run ADB or FASTBOOT commands form Android device to another Android device (the host device is rooted). And if so then how... any ideas or help will be appreciated 😊.
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1answer
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Help identifying this device (Sunflower tablet pp3333) and required linux drivers

Hello, I received this device as pictured some years ago, but was never able to figure out what drivers to use for it. My computer does not have the AT connector or serial port, but I do have a serial-...
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SSD not found anymore (not listed by parted, nor lsblk etc, but bus found in lshw)

I have a dual-boot Windows 10 / Ubuntu 18.04 on my laptop (HP Omen 15-5000 NF) with a PCI-e SSD (I think so). After putting my Windows in sleep mode, it was taking forever so I hard switched it off, ...
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1answer
26 views

__report_bad_irq not getting hit

I am stucked in one issue, in which i am getting __report_bad_irq callstack inconsistently. AFAIK, whenever we have 100000 unhandled interrupts this stack kicks in. Output from cat /proc/irq/128/...
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63 views

how /dev/stdout is pointing to different process separately in linux?

I can understand each process fd 0,1,2 is pointing to /dev/stdin, /dev/stdout, /dev/stderr. If I write some data to /dev/stdin to I was able to receive data from fd 1 of the respective process only. ...
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19 views

What are steps for after debugging the device into linux Hardware?

I wanted to know more about the naming conventions used for naming device files in linux , I have done some search and I found there are some rules and command line tool called udevadm , but I could ...
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1answer
110 views

What does PS in ttyPS* stands for?

What does PS in ttyPS* stands for? Where, in general, can I find the expanded names of devices under /dev?
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1answer
50 views

Suddently my peripherals devices(through thinkpad dock) stop being detected. And strange behaviour

From few days ago, suddenly and randomly my devices disconnect through the thinkpad dock (all at the same time). Sometimes they connect again, but for the monitor (in i3wm) I have to restart the ...
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26 views

Bluetooth device no longer recognized

A few days ago I remove my Bluetooth device on my Linux operating system (Ubuntu 18.04), and when I connect again that device not shown (not output on the screen). How can I undo the "remove device" ...
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57 views

How can I concatenate thousands of files into a single device

I'am using split to cut a an iso into multiples chunks. Then a can use cat to rebuild initial iso that I can convert into a mountable device with losetup and then mount. The problem is when initial ...
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rtl8812bu driver: can only access non encryped ssid's

I installed rtl88x2BU on a new installation of MINT 19.3 (kernel 5.3.0.40), source: github cilynx/rtl88x2BU_WiFi_linux_v5.3.1_27678.20180430_COEX20180427-5959, using the README.md instuctions for DKMS ...
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1answer
112 views

How to check the device number of a device in `/proc/1/ns/{ns}`?

How to check the device number of a device in /proc/1/ns/{ns}? I've read the code for a Go library (see below), which states that it's possible to determine, if a container is in the host namespace ...
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1answer
40 views

External USB-HDD became /dev/sda after power off, how to pin it to /dev/sdc?

Today a fuse blew out which turned off a small server. This server has an USB-HDD connected to it, but since I connected it about 3-4 months ago, I never turned the server totally off (no electricity)...
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1answer
28 views

How to find out the real name of mountable devices?

When I open Nautilus and I go to the other locations I can see my unmounted hdd wich name is /dev/sda1 and it's real name is HDD. How can I found the real name of /dev/sda1 from the command line?
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How to specify reproducible disk partitions in Debian preseed file when device file ordering (sda, sdb …) may change?

I'm about to automate the installation of Debian by using the preseed mechanism (preseed file added to initrd). The computers to be provisioned have multiple SATA disks. I would like to specify in ...

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