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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6
votes
2answers
69k views

/dev/sdb: No such file or directory (but /dev/sdb1 etc. exists)

I'm not sure what is wrong here but when running fdisk -l I don't get an output, and when running fdisk /dev/sdb # I get this fdisk: unable to open /dev/sdb: No such file or directory I'm ...
5
votes
1answer
22k views

Kali Linux and RTL8812AU

Currently I am running into an issue where I can't seem to find a way to identify which WiFi adapter I want to use as my primary in Kali (v 2017.1) My laptop has a normal PCI WiFi card inside however ...
-3
votes
1answer
88 views

Time and again I forget the meaning of a single hyphen in the end of some utility commands [duplicate]

Time and again I come across old codes and recognize a single hyphen in the command's end: mysqldump -u root -p --all-databases | zip "$drt/db-$date.zip" - or wget ${target_url} -O - | tar -xzv --...
0
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0answers
30 views

FreeBSD: how can I check if `/dev/random` is blocking?

So this exact question has been asked many times about Linux's implementation of /dev/random, but I am struggling to find an answer that is FreeBSD specific. From the FreeBSD random(4) man page: ...
0
votes
1answer
27 views

MDADM creates additional block devices

I noticed a strange issue when creating RAID array with mdadm. As far as I see, it creates additional devices of md type. According to the kernel.org documentation, the md device type is Metadisk (...
0
votes
0answers
40 views

Kernel randomly maps storage device to different device file

So this is kind of strange. I was trying to put a screenshot into my Videos/ directory, and while trying to cd where I wanted to go, I was getting I/O errors. For context, I have a storage drive ...
7
votes
1answer
888 views

How to rename devices for graphical output such as VGA0

On my Laptop the names of my graphical outputs change depending on what chip is activated in the BIOS. This leads to problems in some scripts where outputs such as VGA-0 or LVDS-0 are specified. So I ...
0
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0answers
28 views

Query the target device for installed PCI devices on ubuntu

Is there a way to query the target device for installed PCI devices on ubuntu. I use VideoCapture Card and 8 cameras. Every time /dev/video* changes but I would like to assign a camera to specific /...
18
votes
3answers
61k views

How to Reset/Cycle Power to a PCIe Device?

I have a PCIe device that only works correctly when the computer is fully powered off then on again. Issuing a simple reboot or reboot -p command does not appear to cycle the power to the PCIe card, ...
1
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0answers
35 views

Jetson TX2 device tree, i2c nodes and camera driver loading

I am a bit confused with behavior of Jetson TX2 when loading drivers for camera. Here is definition of IMX274 in device tree: i2c@3180000 { reg = <0x0 0x3180000 0x0 0x100>; ...
1
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0answers
12 views

Automatically remove a device from /dev

I am having keyboard problems, with a laptop built in keyboard. I have an external keyboard, so wish to disable the internal one. So far I have discovered that I can disable within X11 using xinput ...
1
vote
1answer
998 views

(Linux) unable to mount from initramfs [closed]

I am trying to install Linux (Debian) on a new laptop. This requires special care because the laptop keyboard needs a kernel patch (and I have not compiled a kernel for about 10 years). Also, because ...
2
votes
2answers
57 views

How can I disable an input device?

I have a broken laptop built-in keyboard (The shift-button sometimes gets stuck down). I exclusively use an external keyboard, but the internal keyboard interferes with it. (I can not unplug the ...
0
votes
1answer
961 views

Udev Rules Not Running

I'm playing with Udev Rules on OpenSuse Leap, and I'm trying to run a simple and small script once a USB device is plugged into my system. However, my script which I added in my keyword "RUN+=" does ...
1
vote
1answer
1k views

Disable Ethernet Hardware Devices at start-up

To startup vm called "sys-net" in Qubes on my laptop need to write "1" in file echo -n "1" > /sys/bus/pci/devices/0000\:04\:00.0/remove also 0000:04:00.0 and 0000:04:00.1 are conflicts and need ...
0
votes
0answers
9 views

eCSPI with different MOSI, MISO and SCK per spi_device

The manufacturer's device tree setup for ecspi1: &ecspi1 { fsl,spi-num-chipselects = <1>; cs-gpios = <&gpio2 30 0>; pinctrl-names = "default"; pinctrl-0 = <&...
1
vote
1answer
62 views

What is the use of the dummy device?

I am checking the code of the dummy device driver. The dummy_xmit() function destroys the packet. I want to ask what is the real use of the dummy device or is it not useful today and is a legacy ...
3
votes
2answers
5k views

How to prevent /sda /sdb changes between boots?

I am going to install Gentoo Linux onto an old hardware, which motherboard is having both IDE and SATA hard drives. I have two IDE and one SATA hard drives connected, and plan to do RAID on them. ...
-1
votes
1answer
42 views

make a pseudo device like /dev/random that outputs primes?

/dev/primes is what I want without writing C code just python which I have known and easily written the program. The device file should be similar to /dev/urandom that outputs primes instead of ...
4
votes
1answer
28 views

How to I set the permissions necessary to make the ioctl CDROM_SEND_PACKET command run?

I've run into an error stemming from lacking permissions when using the CDIO library to issue an eject command to my USB CD-ROM drive. I always get an error message like this: INFO: ioctl ...
0
votes
1answer
17 views

Sort block devices by most recently connected?

How can I block devices by the most recent added ones? No option in lsblk seems to have that functionality.
5
votes
1answer
1k views

Remote Mouse netcat (/dev/input/mice)

I was playing around with nc and I'm discovering how powerful and versatile this tool is. I was wondering how the file /dev/input/mice works because when I do cat /dev/input/mice you see the output, ...
1
vote
1answer
56 views

How can I check the model of a device connected to a specific COM through a ssh connection

I am trying to access a remote machine through ssh and check the model of a device that it is connected to a specific COM port; I know what port it is. I have tried some commands, but they either don'...
13
votes
2answers
1k views

Why are < or > required to use /dev/tcp

When trying to call /dev/tcp/www.google.com/80, by typing /dev/tcp/www.google.com/80 Bash says no such file or directory. When looking at other people's code online, they use syntax such as 3<&...
0
votes
1answer
35 views

How do I see that a device is mounted with `exec` option using either mount or /proc/mounts?

I've mounted a cdrom device with mount -o exec /dev/sr0 /media/cdrom0, since I couldn't execute files on it, when the drive was initially mounted by the virtual machine. Now, when I run cat /proc/...
0
votes
1answer
577 views

KDE Connect to Sync Android Device with CentOS 7

What are the KDE Connect process and packages that needed to sync android devices with centOS 7. I want to bridge centOS and android but couldn't find any solution online.
3
votes
1answer
1k views

Can I use a parallel port as a CUPS input device?

I have an old piece of a hardware that does diagnostics on medical equipment. It prints out results over a parallel port. Is there any way to have CUPS accept jobs from a parallel port and redirect ...
1
vote
1answer
1k views

How to associate physical usb port with usb device number

I'm using Ubuntu 12.04. I need to send a command to a device that I have connected on a port of my PC. I can send the command by finding out what the Bus and Device number are. For example, lsusb ...
0
votes
1answer
43 views

Partition table & filesystem for a USB flash drive

I've got a USB flash drive I want to use on printers, audio equipment, and other various devices. In my experience, most Linux is very forgiving about what partition table and FS type I use on my ...
0
votes
1answer
2k views

Unable to connect to USB CDC device

I have an 8 channel USB Relay board which I have connected via USB. The manual for the board states that: To use this product with Linux, USB CDC driver needs to be compiled in with the kernel. ...
4
votes
5answers
11k views

No space left on device on CentOS7

My machine which OS is CentOS7 have to backup 50G data into MySQL. But, there is no space left on the device. But there are many spaces on /home. How can I make user that there are enough space for ...
8
votes
2answers
11k views

Map physical USB device path to the Bus/Device number returned by lsusb

I need to get the title of the attached USB device. I can do that with lsusb. udev allows some substitutions when I write rules: say, we can use $kernel to get name of the device, or $devpath to get ...
2
votes
1answer
55 views

FreeBSD: /dev/dsp exists (“ls -al /dev/dsp”), but does not show in “ls -al /dev”

I'm using FreeBSD-12.0-RELEASE-amd64, when I list all the files in /dev, I don't see /dev/dsp (note there's no output after the first command), but when I list the file by explicitly specifying its ...
0
votes
3answers
1k views

how to know which device was open

is there any shell command, can let me know, current open device or device already in operation. For example, I use minicom to open a device /dev/ttyUSB0 or /dev/ttyS0, after I use program open this ...
0
votes
1answer
46 views

Is there a kind of '/dev/null' to fake output file path?

Let says that I have a CLI which transforms a file_a into a file_b like so: transform --input /path/to/file_a --ouptut /path/to/file_b I have developed a program that use this CLI and need to unit ...
15
votes
1answer
1k views

What are nvme namespaces? How do they work?

I've recently begun supporting Linux installed on devices with built-in nvme ssds. I noticed the device files had an extra number, beyond a number identifying the drive number and the partition number....
0
votes
0answers
21 views

How does linux arbitrate access to devices

I would like to know the different methods linux uses to control access to a peripheral device. e.g. for example you have a spi temperature sensor. And multiple threads are trying to get a reading. ...
0
votes
1answer
784 views

What part(s) of the TTY subsystem control the active /dev/ttyN (TTY device driver N)? [closed]

The TTY subsystem contains the TTY driver, line discipline(s) and hardware drivers (keyboard driver, display driver). Let's say I use a virtual terminal/console. So, my current session uses ‍/dev/...
1
vote
1answer
1k views

Run Out Of Space On /dev/sda2

My Linux (Mint 13) laptop reported that 'The volume "Fiilesystem root" has only 0 bytes disk space remaining'. When I ran a 'df' I got the following result:- HP-255-G1-Notebook-PC # df Filesystem ...
3
votes
0answers
421 views

Multiple /dev/video for one physical device

First some specs: my computer is an HP EliteBook 8460p. It comes with an integrated Chicony HP HD webcam. My issue is that a lot of applications (well, at least Skype and guvcview) are displaying ...
2
votes
1answer
104 views

Difference between writing file from /dev/zero and truncate

$ timeout 1 cat /dev/zero > file1 $ wc -c file1 270422016 file1 $ du file1 264084 file1 Questions : (1) How do 270422016 null characters come out to be 264084 bytes (i.e 258M). $ truncate -s ...
14
votes
2answers
43k views

PKCS#7 signature not signed with a trusted key

Installed Ubuntu with SIP disabled on MacBook 2017 - 0 issues, booted in seconds. I have been building it out and created a problem while trying to make the WiFi work. At some point (it was very late)...
50
votes
3answers
45k views

Understanding /dev and its subdirs and files

$ ls -l /dev/stdin /dev/fd/0 lrwx------ 1 tim tim 64 2011-08-07 09:53 /dev/fd/0 -> /dev/pts/2 lrwxrwxrwx 1 root root 15 2011-08-06 08:14 /dev/stdin -> /proc/self/fd/0 $ ls -l /dev/pts/2 /proc/...
3
votes
2answers
84 views

lsblk column “RAND” aka “adds randomness” - what does it mean?

Running lsblk (an excellent command for getting info about the disk configuration from within scripts and OS-agnostic high-level languages) on Fedora 29 like so: $ lsblk --output NAME,FSTYPE,ROTA,...
4
votes
1answer
395 views

Why are there two entries per device on /dev/input/by-path

If I go to /dev/input/by-path I can see my input peripherals. I've got one keyboard and one mouse, and on my platform the output is: pci-0000:05:00.0-usb-0:1.2:1.0-event-kbd pci-0000:05:00.0-usb-0:1....
0
votes
0answers
129 views

Who is causing extremely high CPU usage when writing to SSD?

When writing to SSD (regardless if over file system or directly into /dev/sda) I observe extremely high CPU usage, with top showing CPU: 0% usr 53% sys 0% nic 9% idle 27% io 0% irq 9% ...
14
votes
2answers
3k views

Are /dev/{udp,tcp} standardized or available everywhere?

I've recently learned about the /dev/udp and /dev/tcp pseudo-devices here. Are they specific to some GNU/Linux distributions or can I find them on other unix systems? Are they standardized in some ...
9
votes
2answers
10k views

How to get device filename from lsusb output or by device path

Related question: USB connect/disconnect notification When the device is plugged/unplugged, I get instant notification, that's great. But to make it (almost) perfect, I also want to get device ...
5
votes
3answers
22k views

GSM modem does not create /dev/ttyUSB file

I installed Kannel in a server, and I want to use a GSM 3G USB modem to send/receive SMS messages, as described in section SMS Centers > GSM Modem of the Kannel User Guide. I have already installed, ...
70
votes
3answers
80k views

What is stored in /dev/pts files and can we open them?

According to my knowledge, /dev/pts files are created for ssh or telnet sessions.