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).

learn more… | top users | synonyms (1)

0
votes
0answers
49 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
152 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 ...
0
votes
0answers
51 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 ...
3
votes
2answers
270 views

sysfs and devtmpfs

Ulrich Dangel explains very well the difference between devtmpfs and udev. What about sysfs? I understand that the kernel uses sysfs to export device nodes to user space to be used by udev. So ...
0
votes
2answers
211 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: ...
1
vote
0answers
42 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
88 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
108 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 ...
0
votes
1answer
164 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 ...
1
vote
2answers
143 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 ...
1
vote
0answers
136 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 ...
0
votes
1answer
326 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?
2
votes
2answers
856 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 ...
0
votes
3answers
874 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
0
votes
0answers
66 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. ...
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 ...
1
vote
0answers
73 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 ...
0
votes
0answers
140 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
122 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
62 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
184 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
63 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
67 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 ...
1
vote
0answers
184 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 ...
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 ...
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 ...
2
votes
1answer
659 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... ...
0
votes
1answer
193 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 ...
3
votes
1answer
77 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, ...
1
vote
1answer
64 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
132 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
votes
1answer
120 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
votes
1answer
442 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 ...
19
votes
8answers
3k views

How can I put a bit mask on /dev/zero so that I can get bytes other than zero?

How can I put a bit mask on /dev/zero so that I can have a source not only for 0x00 but also for any byte between 0x01 and 0xFF?
3
votes
2answers
663 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 ...
1
vote
1answer
81 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
votes
1answer
1k 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
votes
1answer
288 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. ...
0
votes
1answer
130 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 ...
3
votes
1answer
131 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 ...
2
votes
2answers
217 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 ...
1
vote
1answer
386 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
votes
1answer
198 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
votes
1answer
746 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
vote
1answer
104 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 ...
6
votes
2answers
107 views

Can a linux filesystem be backed up by copying the file structure tree only?

This might be considered to be more of an academic question but here goes. Returning to Linux after some years away, I installed Ubuntu 15.04 Desktop on a small PC. Looking around the file system ...
0
votes
1answer
584 views

How to get a list of major number -> driver associations

http://www.nostarch.com/tlpi states: "Each device driver registers its association with a specific major device ID, and this association provides the connection between the device special file and the ...
1
vote
0answers
491 views

USB bar code scanner not working on Raspbian

My USB bar code scanner (SYMBOL LS2208) is recognized as a HID. hid-generic 0003:05E0:0600.000F: hiddev0,hidraw0: USB HID v1.10 Device [\xffffffef\xffffffbe\xffffffa9\xffffffbe\xffffffa9Symbol ...
1
vote
1answer
3k views

LVM unknown device: how to recover?

I have a server with two hard drives that I thought I had correctly installed with LVM, until I discovered that the second hard-drive did not actually seem to be used. I investigated the problem and ...
2
votes
1answer
67 views

Why can X11 access the video card?

This one is maybe a bit theoretical, but... How the heck can X11 touch the video hardware? As I understand it, X11 is an unprivileged user-mode program. But only kernel-mode software can access the ...