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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2
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1answer
95 views

Access iphone storage as device/partition

I am working on a project, in which the ultimate goal is to successfully wipe iOS from an iPhone and install TinyCore Linux in it's place. I expected the iPhone to function like an external drive when ...
1
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0answers
91 views

when running `udevadm test`: `no db file to read /run/udev/data/+gpio_sw:PA7: No such file or directory`

I am trying to write an udev rule that matches a GPIO Pin of my Orange Pi (the GPIOs use the gpio-sunxi kernel module). My ultimate goal is to let users who are member of a particular group access ...
16
votes
1answer
7k views

Difference between /dev and /sys/class?

What is the difference between the device representation in /dev and the one in /sys/class? Is one preferred over the other? Is there something one offers and the other doesn't?
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0answers
73 views

Linux doesn't recognize the SSD it's booting from!

I've extended a computer by a SSD and the BIOS recognizes it (and shows its name), but neither Ubuntu 14.4 nor Knoppix 7.6 show it in fdisk's output. Then I copied Fedora 23 WS Live to that SSD (on ...
0
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0answers
16 views

Devices for Analog I/O gone from /dev after reboot

I have a system using Centos 6.6 and another system using RHEL 6.6 on the same architecture that both need analog I/O drivers to communicate with sensors that will be attached to the device. Thus, I ...
1
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1answer
31 views

Are device files implemented by device drivers or OS kernels?

Device files are interfaces of device drivers to user programs. In Linux, is a device file implemented directly by its corresponding device driver, or by the OS kernel (excluding the device driver)?
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0answers
57 views

Write my own sound card driver [closed]

I would like to write my own sound card driver, in order to use my output jack as a PWM (to control a motor). When I run "lspci", the sound card is : Audio device: Intel Corporation 5 Series/3400 ...
9
votes
2answers
14k 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, ...
2
votes
2answers
808 views

Arch linux can't login

My problem is that I can't login. If I try to loggin with correct username and password it doesn't do anything. I have error message on boot failed to create static device Nodes in /dev . This ...
2
votes
1answer
54 views

How to swap out the driver of a network device on a running Debian Linux box?

I've got an embedded/headless Debian Linux box which boots from a read-only filesystem image. The configuration is set up so that I can (seemingly) write to the filesystem, but any changes to the ...
1
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0answers
58 views

There is no /proc/bus/usb directory

I'm running a centos VM on ESXi. Does the /proc/bus/usb directory not show up until a USB device is connected? I just added a USB controller to the VM (it previously had non) and ran lsusb: $ ...
83
votes
6answers
6k views

How are “/dev” Linux files created?

There are special files in Linux that are not really files... The most notable and clear examples of these are in the dev folder, "files" like: /dev/null - Ignores anything you write to the file ...
0
votes
1answer
84 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. ...
1
vote
1answer
56 views

What is /proc/dma? Is it just for legacy support?

I reading a Linux book that told me I can check the dma channels by reading /proc/dma. This is what I see when I run cat /proc/dma: 2: floppy 4: cascade I'm confused because that looks like old ...
1
vote
1answer
85 views

In udev, what kind of device events match ACTION==“change”?

The udev rules I've created so far only deal with devices being added or removed, i.e.: ACTION=="add"... or ACTION=="remove"... I've come across an example of a rule that seems to deal with device ...
3
votes
0answers
29 views

Enumerate valid values for mknod

I have access to an embedded device which has a bunch of block/char files under /dev. However, this is not a satisfying description of the hardware, because since the firmware is shared with small ...
0
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0answers
47 views

Tweaking the tripwire policy to stop checking for /dev/pts/x

Trying to streamline my Tripwire policy file, I see that I get a lot of chatter in every daily check report about ------------------------------------------------------------------------------ Rule ...
4
votes
1answer
150 views

What happened to /dev/raw/?

I am reading an article on LWN and it has an important statement: Raw devices (/dev/raw/rawN) are a special case of O_DIRECT I/O. These devices can be opened without specifying O_DIRECT, but ...
10
votes
1answer
1k views

How do I let an SDL app (not running as root) use the console

I want to use an SDL-based program to display graphics on the console, without having to log on from the console, and without running the program as root. For example, I want to be able to run it via ...
0
votes
0answers
47 views

How to switch Huawei CDMA 2252+ to usb from cd-rom?

I have Huawei CDMA 2252+ phone and i want to connect it to linux to send sms. In Fedora 15 (64bit) it is taken as cdrom. This is the output of dmesg after the phone plug in. [10887.524339] USB Mass ...
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0answers
178 views

Unable to find Documents on iPad device when mounted

It seems that this is a common problem, but there haven't been any satisfactory solutions posted yet, despite existing for years. Briefly, the problem is that when I mount my iPad in Linux Mint, I ...
0
votes
2answers
173 views

Where do the logs directed to /dev/console go?

I'm studying RHEL 7. If I add this line to rsyslog.conf: kern.notice /dev/console Where will the messages with facility "kernel" and priority "notice" be logged? If I run this command: ...
4
votes
1answer
103 views

Where is the default device name (e.g. /dev/ttyUSBx) specified?

I'm investigating dynamic device name mapping via udev. The goal: On a multi user system, each user can allocate and free devices like usb-serial converters or PCIe cards (FPGAs). If an user ...
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0answers
39 views

Can you create a read only encrypted partition that root cannot write to (or remount)?

I have an encrypted partition that I would like to be mounted as read only. The catch is that I do not want a root user to be able to remount the partition as read-write unless they have the ...
2
votes
2answers
84 views

Changing ownership on /dev/fuse - security issues?

In some distributions /dev/fuse is owned by root:fuse while in other distributions /dev/fuse is owned by root:root. I'm using CentOS which belongs to the former set of distributions. And I'm wondering ...
4
votes
1answer
9k views

How do I find out which process is using my V4L2 webcam?

I tried to run the following: $ vlc -I dummy v4l2:///dev/video0 --video-filter scene --no-audio --scene-path webcam.png --scene-prefix image_prefix --scene-format png vlc://quit --run-time=1 ...
1
vote
2answers
129 views

Is UUID really unique? why can we assign multiple UUIDs to single slice of disk

All the web content and its acronym explains it as Uniquely identifier. But when i try to create another device, lets say swap in my case and assign the UUID, i am able to assign many UUIDs to single ...
0
votes
1answer
145 views

No /dev/ttyusb* in Linux

I want to do some serial programming using Python Serial, and all examples I've seen online for USB set the port parameter to "/dev/ttyUSB*" . But on my system, there is no "/dev/ttyUSB*" inspite of ...
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0answers
122 views

udev: Passing parameters via $attr{key} does not work. How to solve it?

I want to enumerate my USB-UART bridges with my own script. The script shall be called with some attributes and return a new devfs node name. I tested the script on console: ./rc3e.py -d ...
7
votes
1answer
505 views

Why does a device show up as hidraw instead of hiddev?

I read the kernel documentation for hidraw and hiddev, and I understand the differences, but I am wondering how the kernel decides whether or not a device should show up as /dev/hidraw* or ...
0
votes
3answers
689 views

Creating a character device file

How to create the character device files? I have tried cat > xxx^c But I can't create a character device file
5
votes
2answers
1k views

Udev rule to match multiple node USB device

I have a 3G/GPS device that creates 5 tty nodes, although it's only one physical USB connection. Basically, a multi port usb-serial adapter. I'm trying to create some udev rules to make sure those ...
0
votes
1answer
284 views

A Start Job is running for dev-md1.device

Hello everyone I'm with the following error on my CentOS 7 I restarted the server is now the boot time is with this message is already so minimum 40 minutes, what should I do? Please Help-me?
5
votes
2answers
1k views

How Linux uses /dev/tty and /dev/tty0

I can see the difference between /dev/tty and /dev/tty0 by testing the provided method from this question. But I really wonder about the practical usage of those devices (like situations they will be ...
0
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0answers
59 views

PCI Device Missing After Reboot

I have a DVBSky T9580 PCI tuner card. My problem is that after rebooting,, the device dissapears, lspci does not list it any more. I tried rebooting with reboot command as well as shutdown -r 0. ...
2
votes
3answers
310 views

/dev/console points to tty0?

I've been trying to understand the /dev/console device, but there are a few things I'm not clear on: What is the purpose of this device? From what I can gather it's just a place for the kernel to ...
1
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0answers
66 views

Disable embedded keyboard when in a tty

I've been lately working on a netbook. I like to connected an external keyboard and mouse to it whenever I can, and I put the keyboard over the embedded keyboard. When on X, I used xinput to disable ...
3
votes
2answers
92 views

How to temporarily disable mouse device?

I have wireless USB keyboard and mouse combo. I need a way to disable mouse while leaving keyboard function working and a way to enable it again after some time. I don't use X and I can't make it in ...
0
votes
0answers
114 views

(Linux) unable to mount from initramfs

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 ...
0
votes
1answer
109 views

Linux UART IO File

How bytes received on UART device are stored in some serial Linux devices /dev/ttyS? How to read them? What is the procedure? Should that device file be closed, when new data is arriving?
2
votes
1answer
59 views

How many distinct video cards do I have?

I'm logged on to a remote machine and I'm trying to determine how many video cards are installed. The machine was built for CUDA operations so it's likely to have more than one NVIDIA card. > ...
0
votes
1answer
171 views

how to set i2c bus to soc audio codec

I'm working on an audio codec driver for cs4245 device. It's controlled by i2c. I have 2 hardwares (devel-board), one of the them has the codec attached to i2c-1 and another to i2c-2. The first one is ...
3
votes
1answer
61 views

Which device is working

I have one dvb-t and one dvb-s card in my system which are in /dev/dvb/adapter0 and /dev/dvb/adapter1 Is there a way to find out which card is currently working? and which one isn't?
1
vote
0answers
64 views

Write shrunken .img file to device file

I have a backup image of a device file /dev/sda3 that I created using: dd if=/dev/sda3 of=~/sda3.img. The image is very large, so I have re-sized it to remove empty space. My question is can I ...
21
votes
3answers
13k 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 ...
2
votes
1answer
319 views

Webcam Device Driver to support H.264

I have a Creative Live Cam Connect HD (id: 041e:4093) and this webcam has an on-board H.264 encoder. Unfortunately v4l2 only inputs the feed as MJPG. $ v4l2-ctl --list-formats ioctl: VIDIOC_ENUM_FMT ...
1
vote
0answers
71 views

Help me to find my speakers and headphone paths (name of PCM device)

I am really confused trying to get my speakers and headphone device PCM names like a "hw:x,x" or something like that; cat /proc/asound/devices 2: [ 0] : control 3: [ 0- 0]: digital audio ...
5
votes
2answers
2k views

How can I create a direct 8khz audio pipe in Ubuntu?

I'm interested in creating musical programs like these: http://www.youtube.com/watch?v=GtQdIYUtAHg&feature=player_embedded Essentially these programs just generate sequences of integers, which ...
0
votes
0answers
27 views

KVM and peripheral devices

How does KVM work with peripheral devices? Are devices emulated in user space or in kernel space through the device driver? The host and guest operation system cannot claim both a device, and how ...
0
votes
1answer
178 views

What is the difference between loop device and block device? [closed]

I want to create a loop device myself, I want it to have a special name, say /dev/loop-test-0. I want it to be up after I reboot the machine. I though that I can use mknod for this, but this doesn't ...