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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canonical/non-canonical vs raw/cooked?

In the context of terminals, what is the difference between the two opposites canonical/non-canonical and cooked/raw? This thread says that they are synonym. But that's weird because one of the "...
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debugfs on a NAS

# debugfs -R 'stat <INODE>' /dev/sdaX or # debugfs -R 'stat FILENAME' /dev/sdaX> display file creation time etc. How to run this command if the DEVICE is a NAS mounted e.g. on /MOUNTPOINT/VOL-...
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How can I permanently change a network device name in CentOS8?

I want to permanently change the device name of a network interface using a portable script. The interface gets the ugly name of enp02fghjkl1. I want to give a pretty name of netface1. I have tried ...
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Find physical machine associated with /dev/pts/N

If i have an operating system with multiple users logged in via ssh, is there any way i can find which physical machine is associated with each /dev/pts/N (where N is an integer)? All i know is the ...
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Change underlying device of mount or dm-crypt without unmounting

I have an external, encrypted USB-drive that was mounted through dm-crypt: The device was /dev/sdb, decrypted as /dev/mapper/external (which is a symbolic link to /dev/dm-5) and mounted as /mnt. After ...
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When is mandatory use /dev/zero over /dev/null for write/discard purpose?

According with the FHS about /dev at: 6.1.3. /dev : Devices and special files it contains: The following devices must exist under /dev. /dev/null All data written to this device is discarded. ...
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Automatically lock my Linux computer when I walk away from it

I would like to lock my Linux (GNOME) machine after I walk away from it. Ideally, it should be a small Bluetooth tag / card that I carry in my pocket with a proximity sensor. Is there some software ...
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Why does device registration not create a device file?

I'm currently learning about Linux device drivers and feel as if I have a fundamental misunderstanding on how devices are instantiated in Linux. Within a Linux module, I can call alloc_chrdev_region() ...
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What's the difference between structures "cdev" and "inode" in the context of device driver programming?

I am currently studying device drivers in an operating systems course and am getting confused regarding the difference between the "inode" structs and "cdev" structs. Could someone ...
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Why aren't my audio devices recognized?

On my laptop, only Dummy Output appears in Sound Preferences. This is Mint 20.3, but similarly, nothing is found when running on with an Endeavor or Fedora live-USB-stick. Headphones in the AUX do ...
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What happens when Linux goes out of letters for drives?

Let’s say I have 50 USB flash drives. I assume they get to be /dev/sda to /dev/sdz. What comes after /dev/sdz?
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Does a PCI device like PCI card reader or PCI usb host controller need to have a device attached to it to perform DMA attack

Am beginner to Unix systems and i have a simple idea about DMA attacks. While trying to install Qubes OS i want to know if it's safe to install it directly from the hard disk, assuming the PCI devices'...
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How do I "get write permission for device files" in Linux?

I have just install brightnessctl to control my screen brightness, but can only run it as root. Doing otherwise prints the suggestion I "get write permission for device files". What is the ...
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dev/rfkill and PyRIC library, rfkill.py: rfkill_list() problem not all devices found

I am playing with a piece of code from : https://github.com/wraith-wireless/PyRIC/blob/master/pyric/utils/rfkill.py, trying to get rfkill_list() using Kali-linux (should be Debian rolling ... ??) #!/...
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Printing out the contents of /dev/nvme devices : what does it represent?

Out of curiosity I've decided to call cat on one of my nvme devices with the following command : sudo cat /dev/nvme0n1p1 It started printing out gibberish but now I wonder : what data does this ...
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How to increase size of software RAID0 Arrays?

My Raid0 array consists of two partition components. [root@rhel-85 ~]# mdadm --detail /dev/md0 /dev/md0: Version : 1.2 Creation Time : Sun Jan 9 17:25:26 2022 Raid Level : ...
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How to get a PCIe Mini-SAS card working in Linux?

I can't seem to get this PICe card working and I can't find any info/drivers about it on the internet. All the SATA HDDs in my server are connected using this card which came with the system. It works ...
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/dev/ttyACM0 and lsusb

Can someone explain me the connection between /dev/ttyACM0 and the output of lsusb? I am following this instructions. It says "Update ttyACM0 to match your adapter location." I do not know ...
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Search full device for magic number as hex

I am currently trying to solve a forensic file hunt training question. There were hints given, that there is a LUKS container and that we need to find the LUKS header in order to go on with the next ...
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UHID Keyboard not interacting with Window Manager

I'm trying to get the following UHID device code working on my machine. It is supposed to be sending random keystrokes to my Window Manager, but it isn't. I wonder if this has to do with udev not ...
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How to find the complete path of a usb device connected via multiple hubs

0 My linux pc(ubuntu 20.4) is connected to 3 cloud ripper device.This cloud ripper has 3 UART port which inturn is connected to a hub and the hub is connected to another hu and the hub is connected to ...
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How to disconnect/disable MMC SD card

I have non USB MMC/SD reader slot . If a user inserts SD card, I want to be able to disconnect the SD card, or Disable the reader. (in case I detect malicious card). How can I do this? With umount, I ...
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How to block all wireless non-bluetooth devices using udev

How to block all wireless non-bluetooth devices in udev (that require an USB adapter to attach to computer) ? I want to block permanently all wireless HID devices such as wireless mice or keyboard .
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Are there specific folders in the file system that cannot be written to?

Leaving aside the need for that, I wanted to write (create a file) into /sys/devices/pci0000:00/{one-of-the-devices}/. Running touch a returns touch: cannot touch 'a': Permission denied. (I read ...
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How to change sdb label into sda (if possible)?

I have recently installed 3 Ubuntu 20.04 nodes. In one of them the system was installed on /dev/sdb instead of /dev/sda (apparently the sda label was used by the usb stick from where I installed the ...
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How to mute/unmute default sound output

What's the generic way to mute/unmute my system's default sound output? $ amixer set Master mute amixer: Unable to find simple control 'Master',0 $ amixer scontrols Simple mixer control 'IEC958',0 ...
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Possible reasons for redirection to /dev/null suddenly breaking

I am using a Bash loop to monitor a process that I spawned, and after some time (hours/days) it sometimes produces an "operation not permitted" error trying to redirect output to /dev/null: /...
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Discrepancy of disk size in fdisk command output

I have created CentOS 7 VM in oracle VM box with the disk size of 10 GB. When I run fdisk -l /dev/sda command, it reports that the disk size is 10.7 GB. Can someone explain why fdisk shows higher disk ...
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How can I find out which device or resource is busy?

I'm looking for advice troubleshooting an issue related to 'cgroups' on Ubuntu 18.04. An application (Mullvad) gives the following error in journalctl: [mullvad_daemon][ERROR] Error: Unable to ...
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What happens when an SD card gets connected to a Linux computer

I'm still quite confused as to how this works exactly. When we connect an SD card to a computer running a Linux system, this is my understanding (Please feel free to correct on the smallest of details ...
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What does the output of `ll /proc/self/fd/` (from `ll /dev/fd`) mean?

Related, but not duplicates: /dev/fd inconsistency How does /dev/fd relate to /proc/self/fd/? Why does process substitution result in a file called /dev/fd/63 which is a pipe? On Ubuntu 18.04 and 20....
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When is the devicetree parsed to populate the device list on arm64 architecture?

This question comes from my attempts to understand how a built-in platform device driver is initialized at boot time. I am using an embedded linux distro (Yocto) on a SoC (ARM + FPGA). The device ...
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How to merge unallocated disk space in a device in another device?

when I'm doing "fdisk -l" we can see : Device Start End Sectors Size Type /dev/nvme0n1p1 2048 1050623 1048576 512M EFI System /dev/nvme0n1p2 1050624 500117503 ...
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My external HD corrupted after forced reboot

After update kernel, I forced reboot and canceling jobs what running in shutdown. The external hard drive is corrupted and does not display in /dev. Relevant information in log: [sda] 0 512-byte ...
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USB 3.1 hub doesn't work properly on Thinkpad laptop

for quite a long time I was using USB 3.0 hub with my mouse, keyboard, Audio DAC, and xrl to usb interface. Everything was working fine but recetly I decided to buy new USB 3.1 hub, this time with a ...
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Listing on board/integrated devices on Linux - for instance, on board keyboard

Relevant to laptops only - I am trying to list all on-board (integrated) devices on laptops - such as on board keyboard, mouse touchpad, video card, etc shipped with the machine. What is the best ...
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How can I find the usb devices camera?

I am begginer in LINUX, sorry if my question isn't the best. I have a c++ app that uses OpenCV lib. This app runs at startup via a service(using systemctl). My app needs as arguments, the id of usb ...
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Packet redirection between two network device

To run a particular application on openwrt, I would need to get a bidirectional fifo (direct transmission of network packets) between a device tun0 (openvpn) and br-lan (Ethernet). In other words, the ...
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Reading an infinite data in Python and feeding to another external process

I am using Python to read data from a TRNG (true random number generator) device, and I want to feed this data to an external utility (e.g., dieharder). The data itself is an indefinite stream, but ...
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What would need to be changed to create a new standard stream?

Hopefully this question isn't too abstract, it touches on a bunch of software throughout the stack. We all know about /dev/stdin, /dev/stdout, and /dev/stderr. What if I wanted to create a new ...
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Is it possible to make a device accessible exclusively by certain programs?

I have a device (a video card) that I need only two programs (expressed as paths, e.g. /usr/bin/myprogram) to access. The device has a /dev file (e.g. /dev/mydev1), but I can also use other references ...
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What is the preferred way to read data from kernel space devices into user space processes?

I am currently querying my sensors by first opening a file descriptor of the device node, calling read() on it and closing the file descriptor again. For dynamic sensor data I would repeat this ...
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When ever new i2c device(slave) is inserted/poweredON, kernel/host has to detect slave device dynamically just like USB. How to achieve it?

The power conditions are that the i2c device(slave) is powered off and the host controller is on. And kernel module should be loaded while booting. When ever new i2c device(slave) is inserted/...
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How I can distinguish whitch /dev device is the phon1 in my router running openwrt?

In my router (Fritzbox 7360) I havce installed openwrt, and I want to access at low level the port used for analogue telephony, so I can output some audio via it using a custom script or software. In ...
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i2c port change randomly

I'm using an Up squared computer. I connect a device via the i2c port in the HAT connector. When using i2cdetect I detect the same device (identified by the address) on different ports. Changes occur ...
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How do I combine two "devices" so that I can expand a partition that I want to span both on Ubuntu 20 LTS without a GUI / GParted. (SSH only.)

I have been looking all over to figure out how to expand a partition on one "device" to use space on another "device". I am putting quotes around device because that is what it ...
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How do I remove a manually added webcam entry?

I'm using Manjaro, and my system information is given below: OS: Manjaro Linux x86_64 Host: HP Pavilion Notebook Kernel: 5.10.42-1-MANJARO Uptime: 18 hours, 2 mins Packages: 1586 (pacman), 11 (snap)...
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Block special file for first session of multisession CD

I have a multisession CD. The first session is CD audio tracks and the second is an SVCD q.v. "CD Extra" and "Blue book". When played on a CD player, the audio tracks are (until ...
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Audio devices on vncserver Tigervnc

Hi i have a question about audio devices on a vncserver "TigerVnc" I have done the Follow and it woks i don't want to create a virtual audio server not at all i just want to the audio ...
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How to press a key of a peripheral device (not keyboard) from terminal/python?

I have recently acquired a dial indicator and a keyboard like device that when attached to the dial indicator it types the value of the dial indicator on the computer. It is similar to a keyboard. ...
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