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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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
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1answer
455 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
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3answers
246 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
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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
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1answer
170 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
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2answers
630 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 ...
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0answers
40 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
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3answers
291 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 ...
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0answers
44 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
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2answers
73 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
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0answers
67 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 ...
38
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2answers
11k views

How to create /dev/null?

I successfully deleted my /dev/null. How can I restore it? The OS is Ubuntu.
0
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1answer
83 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?
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1answer
50 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
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1answer
106 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
56 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?
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0answers
49 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 ...
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3answers
11k 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
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1answer
295 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 ...
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0answers
58 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
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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
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0answers
24 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
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1answer
114 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 ...
2
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1answer
333 views

How to get /dev/ttyUSB* to show up?

I've been using FTDI usb serial cables on OSX with really no thought for years. Now, I'm trying to get the same cables working on Linux (Linux Mint, Debian Edition 2). What I understand so far is... ...
90
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12answers
371k views

How do I find out what hard disks are in the system?

I need to know what hard disks are available, including ones that aren't mounted and possibly aren't formatted. I can't find them in dmesg or /var/log/messages (too much to scroll through). I'm hoping ...
3
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1answer
51 views

Is there any way to prevent a bad drive from disappearing from /dev?

I'm trying to recover a partition on a bad drive with ddrescue. I run: $ sudo ddrescue -r -1 -v /dev/sdd3 OUT.img dd_rescue_logfile and it seems to do great for a while, but after about an hour, ...
3
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1answer
30 views

give group permissions to specific device

I have a panning web camera I built, (future robot arm). The camera pans via a web interface (cgi scripts and JS interface) which access an arduino. To enable sending of commands via the interface, I ...
0
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1answer
107 views

Platform Device Drivers

I was just going through the code of kernel. I have a raspberry Pi board. I want to interface the touch screen with my board. I want to develop the Platform driver for that. As per the documentation ...
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1answer
146 views

Is the device tree compiler tied to the kernel version?

I have a situation in which same device trees are used with different kernels. Can the device trees be build only once and used with all kernels? The reason I ask this is because I found the device ...
1
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1answer
52 views

To which device file is particular storage device mapped?

I noticed that I never figured this out completely. Linux maps SATA and USB (and many more kind of) storage devices to /dev/sd[a-z] device files in the order in which they were "found". Now given that ...
2
votes
1answer
81 views

Redirect or trigger on dev node input event

Is it possible to trigger an event when data is available at a dev node? Very simply, if some widget device sends information over usb to my linux box, would it be possible to trap into some event ...
2
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1answer
84 views

How can I give a user the CAP_MKNOD capabillity?

Following on from this question: rsync's relationship with special files In order to back up device files, rsync at the destination needs to be able to call mknod. The usual approach would be to ...
4
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1answer
225 views

rsync's relationship with special files

I'm trying to transfer some existing backups from one system to another. The older backup system seems to have managed to back up special files like /dev/hda, /dev/tty0, and /dev/null which look like ...
13
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4answers
6k views

Can I setup a loopback audio device?

If I can send audio to the output devices, then I can record the same audio as a wave. With filesystems, you can just setup a loopback filesystem and write binary data on a file instead of a device. ...
0
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1answer
1k views

What are high level and low level device drivers

Recently I read that there are two types of drivers (at least for disk), one that are called high level drivers and another called low level device drivers. Can some one tell me what these are, and ...
3
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2answers
416 views

How to skip special / socket files during rsync transfer?

Using the following command. rsync --archive --delete --partial --progress --recursive --no-links --no-devices --quiet source target Using --no-links and --no-devices already. Getting the error ...
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1answer
69 views

What are some common use cases for creating block/character device files from the shell with mknod?

I understand that block/character device files are created programmatically (by the drivers themselves?) to facilitate communications with device drivers using standard I/O calls. But why one would ...
2
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1answer
598 views

Changing the /dev/tty* permissions at startup

My solution (ArchLinux ARM on RaspberryPi) requires that a non-privileged user has to have access to the /dev/ttyAMA0 port. In final implementation that user will be automatically logged in and a ...
4
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1answer
186 views

why isn't monitor listed under /dev in linux?

If /dev is suppose to list all the devices that is connected, like usb, hdd, webcam, how come on my ubuntu 15 VM I don't see a monitor? I am running the desktop edition so there should be a monitor. ...
3
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3answers
364 views

USB device to be detected at the “same” /dev point always?

In Linux (actually I'm with CentOS v6.5), whenever I plug in my USB Terminal/Character Device (some kind of USB Adapter) for the first time (after booted), it is detected at: /dev/ttyUSB0 But ...
5
votes
4answers
5k views

Prevent claiming of novelty usb device by usbhid so I can control it with libusb?

I have a USB rocket launcher that I wish to experiment with through libusb. However, libusb cannot claim the interface; presumably because the output of usb-devices lists 'usbhid' as the driver for ...
0
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0answers
8 views

Discrepancy in Owncloud drive size

I have ownCloud running on Debian Raspberry Pi with an 8Gb USB as the drive. Checking the USB is mounted correctly: df -h /dev/sda1 7.3G 20M 6.9G 1% /media/owncloud But my ownCloud Mac ...
3
votes
1answer
105 views

How do I check if sound card is in use and, if possible, which process is using it?

I want to know if a program is using my sound card without my knowledge. I thought about building a program that uses low-level device driver code to do the trick, but am now interested in seeing if I ...
8
votes
3answers
11k views

How can I tell whether a network interface is physical (device) or virtual (alias)?

I have a small home router running OpenWrt (Kind of embedded Linux for routers). It has five Ethernet ports, one labeled WAN and four labeld LAN 1 to 4. It has the following Network Interfaces defined ...
2
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2answers
166 views

How do I recreate /dev/ttyUSB## devices that I deleted?

Background It seems I only know enough linux to get myself in trouble. I'm working on a couple of embedded systems (two different models) both running linux. I've been troubleshooting a modem ...
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1answer
237 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 ...
2
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1answer
139 views

mmap /dev/random

Why is it that I cannot mmap /dev/random or /dev/urandom on Linux? I get errno 19 which is ENODEV. When I try the same code with /dev/zero it works. int fd = open(path, O_RDONLY); assert ...
0
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1answer
503 views

Lvreduce online on RHEL 6 or centos 6 with ext4 file systems

Is it possible to reduce a mounting lv safely at RHEL6/CentOS6 with ext4 file system? If it is, how can I do that?
1
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1answer
87 views

OSX: MBP: How does system detect sd card inserted?

I have a MacBookPro running Mavericks. I can insert one sd card into the slot and it mounts just fine. Another sd card I slip in and nothing happens. It does not appear in disk utility. It does ...
1
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1answer
4k views

Why is my Mac, upgraded from Mavericks to Yosemite, no longer giving VMware Fusion needed resources?

I have a Mac upgraded from Mavericks to Yosemite. When I tried to run VMware Fusion, I got an error stating: Could not open /dev/vmmon: No such file or directory. Please make sure that the kernel ...