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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4
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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
0answers
181 views

Mount partition with truecrypt using the commandline

I'm trying to mount a encrypted HDD with truecrypt, but I cann't find the device. Where can I finde my HDD and what is the command to mount it in truecrypt? I'm using Raspbian on Raspberypi.
2
votes
2answers
4k views

Allow non-root user to read/write /dev files

In my /dev folder, I would like the following files to be user readable and writable: /dev/ttyUSB0 /dev/gpib0 How do I do this without using chgrp? I can edit /etc/udev/rules.d but I do not know ...
1
vote
1answer
201 views

Disable emulated scroll wheel (EmulateWheel) for specific programs

Is it possible to disable evdev's EmulateWheel option when using specific programs? In my use case, I would like to be able to interact with the Acme text editor and with some VMs using my Thinkpad's ...
3
votes
1answer
372 views

Why does the SELinux filesystem have it's own null device?

Looking through /sys/fs/selinux, I found this: # ls -l /sys/fs/selinux/null crw-rw-rw-. 1 root root 1, 3 Jan 24 02:47 /sys/fs/selinux/null Which is identical to /dev/null: # ls -l /dev/null ...
1
vote
1answer
127 views

Getting message “Error trying to open /dev/dvd exclusively” at the end of a DVD burning process when using growisofs

I am using Linux Fedora Core 4 (have to work with a legacy system) and trying to burn DVDs as a non-root user using the growisofs utility. I seem to be getting this error message at the end of the ...
1
vote
1answer
203 views

Permission of DVD device file not being retained when machine is rebooted

I am using Linux Fedora 4 and would like a non-root user to be able to write to DVDs using the DVD drive. I was able to do this by adding write access to the group of the device file /dev/scd0 and ...
1
vote
0answers
117 views

Create a fake read only device like file with incrond

I need to generate UUID with uuidgen (not through any function call, but external command, because processes which will read the file cannot call any APIs or external commands directly). My idea is ...
4
votes
1answer
2k views

can not create /dev/shm

I need to create /dev/shm on an embedded ARM system. From "Installed The Latest Changes to Current and......". I see that it can be created with mkdir /lib/udev/devices/shm, but I'm wondering what ...
4
votes
1answer
5k views

How creation of new USB device file in /dev/bus/usb/001/ directory work?

I noticed that every time I connect a USB device, a new device gets created in the /dev/bus/usb/001/ directory. Further on each reconnection of the same device, the "Device Number" and "ID" change. ...
3
votes
3answers
417 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 ...
3
votes
2answers
187 views

Is there a uniform way to discover information about devices?

UPD: Changed question title from manage devices to discover information about devices One of the frequent thing I do is look up info about devices on my systems. And I am constantly find myself ...
2
votes
1answer
83 views

What happens under the hood when some data is sent/received on an uart (or similar)?

I am trying to understand how computers work and I was thinking about peripherals. Here is what I understand so far but some parts are missing. Using an Arduino, I send some text every second (a then ...
6
votes
3answers
4k views

Why won't Linux let me play with /dev/dsp?

I'm working through a Linux textbook, and it's telling me about devices. It says that if I send the appropriate output to /dev/dsp, then it will play a sound. The example is cat file.wav > ...
0
votes
1answer
520 views

How to debug a device that changes from /dev/ttyUSB0 to /dev/ttyUSB1 at will?

I have a device plugged to a CentOS server that changes randomly from /dev/ttyUSB0 to /dev/ttyUSB1 and vice versa. The device I'm trying to connect is this one. How can I debug this?
2
votes
1answer
4k views

Difference between Device file and device drivers

I am beginner in device driver programming. I don't get the difference between device drivers and device files in Linux. Can anyone explain the difference?
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 ...
2
votes
1answer
330 views

2 or more programs in same USB serial converter

Having a network of lets say 10 devices in RS-485, connected to the linux PC with a RS-485 to USB Converter. Already there is a C program interacting with the serial converter at /dev/ttyUSB0. My ...
1
vote
0answers
143 views

Which Unixes support cross-device filesystem links (in particular for rename)?

Just read the following on the FreeBSD man page for the rename syscall: ... [EXDEV] The link named by to and the file named by from are on different logical devices (file systems). Note that ...
2
votes
0answers
615 views

Debian Wheezy USB2 ehci_hcd

I have a friend who decided to switch to Linux from Windows. I was helping her to get up and running as quickly as possible but we ran into a problem which I can't seem to solve. She uses Debian ...
5
votes
2answers
328 views

Can you identify transport via sysfs?

I'm writing a script, and I'm interested in being able to identify the transport class (fc - "fibre channel", scsi, iscsi, etc.) for a given block device. I can retrieve this information via ls -l ...
3
votes
2answers
509 views

Permissions to print directly to USB printer

I've a netbook with Linux. I've a usb/serial printer and I added the line chmod 666 /dev/tty* to rc.local and it prints straight after a reboot. When I close the lid of a netbook for a while and then ...
4
votes
0answers
220 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 ...
35
votes
3answers
31k 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.
3
votes
1answer
3k views

Unable to use busybox implementation of hwclock

I have a buildroot generated kernel (3.6.11) and root file system running on an x86 device. It uses busybox and I am trying to set the BIOS hardware clock using hwclock. I get this error whenever I ...
0
votes
1answer
95 views

Random bug in Linux

Some time ago, I remember reading an article on randomization in computing, and how random you can actually get a system to be. The article came about, if I'm not mistaken, because of some seemingly ...
0
votes
2answers
188 views

ECC on a single block device

I have an SSD that I suspect failing silently now and then. I have run badblocks on it and it is clear that it is not bad sectors but might instead be some race condition in the electronics, in which ...
2
votes
1answer
906 views

udev Unable to Rename Network Device: Device or Resource Busy

I'm trying to use udev rules in order to give my network interfaces static, consistent names. However, it seems like there is some race condition happening preventing these rules from consistently ...
0
votes
2answers
491 views

IO utilization for /dev/null redirection?

I always use nohup to start my system. However, the output to nohup is so big that I'm thinking to redirect it to /dev/null. My concern is, will redirecting to /dev/null also incur some I/O operations ...
2
votes
1answer
256 views

GPS Device Attached to Linux Mint 15

I purchased a Silvercrest GPS device from Lidl recently, but the software that came with it is a tad "underpowered" to say the very least and has no Linux support. I'm attempting to get at the raw ...
1
vote
1answer
2k views

“Permission denied” when writing to /dev/stdout

Why cannot I write to /dev/stdout? I am logged in as the root user, what greater permission could I have? root@ubuntu:/# tcpdump -i 2 -w /dev/stdout tcpdump: /dev/stdout: Permission denied The ...
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 ...
1
vote
1answer
1k views

Beaglebone Black Device Tree for LCD4 cape

The device tree for LCD4 cape is located at /lib/firmware/BB-BONE-LCD4-01-00A1.dts When I looked into it, the declaration of those GPIO buttons confuse me. There are five buttons according to ...
2
votes
1answer
1k views

ffmpeg webcam to device driver , output 8 bit grayscale

With the following command i'm trying to capture 10fps and send them the device driver. Now i want 8 bit gray raw frames (640x480= 307200 bytes per frame) to be send to the device driver. I can't ...
6
votes
2answers
6k views

/dev/hidraw: read permissions

What do I need to do to have read permissions on /dev/hidraw*? I'm seeing stuff about udev rules and saw this on the net, but the world of udev is like a foreign land to me, and if there's some sort ...
5
votes
2answers
2k views

How to take sha-1, sha-256 or MD5 of CDs / DVDs?

I just tried burning both a Debian CD and a Debian DVD from their .iso files and I've got a weird behavior: the checksum of the CD is correct but the one of the DVD ain't. Here's what working: ...
4
votes
2answers
4k views

What is a device controller, and where does it fit in between the kernel and the device?

Can someone please explain the concept of a device controller (hard disc controller, NEC PD765 compatible controller etc.). Here are some definition of key terms which might be needed for the ...
1
vote
1answer
724 views

dd outputting: “function not implemented” when trying to write to /dev/sg11

I'm trying to use the following command: dd if=/dev/urandom of=/dev/sg11 bs=16K count=1 But when executing it, I get the following error: dd: writing `/dev/sg11': Function not implemented When I ...
1
vote
1answer
89 views

Need list of HDD devices excluding my os HDD

I want list out whole HDD device excluding my os running device attached to my system. I did lot's of googling and fired many more commands in command line of linux. but can't gating proper output. ...
3
votes
1answer
691 views

How to get the actual keyboard device given the output of /proc/bus/input/devices?

When I run: cat /proc/bus/input/devices ...I receive the following output: ... I: Bus=0003 Vendor=040b Product=2000 Version=0110 N: Name="Generic USB Keyboard" P: Phys=usb-0000:00:1d.0-1/input0 ...
1
vote
2answers
1k views

Meaning of “target” in virsh XML VM definitions.

I recently found that the target=hda tag in virsh was actually not translating into guest OS (guest OS's use /dev/sdX as the disk device names, in general, it seems). virt-install and /dev/hda vs. ...
1
vote
2answers
2k views

virt-install and /dev/hda vs. /dev/sda

It appears that my virt-install xml file (i.e. created when defining a VM) specifies targets "hda", "hdb", and so on as the devices for disks, however, the VM, once created, lists /dev/sda, /dev/sdb, ...
3
votes
1answer
758 views

Why are devd rules applied before devfs rules?

My problem I have the following lines in /etc/devd.conf which execute the usbhidaction for a /dev/uhid* device with the named vendor and product id. attach 100 { match "vendor" "0x046a"; ...
0
votes
2answers
891 views

Cheap 100% Debian compatible ultrabooks [closed]

I'm looking for relatively cheap ultrabooks with 100% Debian compatible features. I have several ultrabooks on my list but they contain some additional features which i don't need (additional ...
6
votes
1answer
2k views

Find out if a specific device is an USB mass storage

Context I'm automating SD card imaging from an existing dd factory image. The SD card is always connected through an external USB card reader and thus appears in the system as a SCSI block device ...
1
vote
0answers
927 views

Check if Keyboard and Mouse are plugged in

Is there a way to detect if a keyboard and a mouse is plugged in (and working) in Linux? This will be embedded in a PXE setup, so I only have Kernel + Modules and Busybox available. Bonus question: ...
2
votes
1answer
3k views

“PS/2 Generic Mouse” gets lost. How to reload without reboot?

I am running Ubuntu 12.04LTS on a ThinkPad E420s. My Trackpoint is recognized as "PS/2 Generic Mouse". My problem is that it doesn't load/disappears after booting or after suspension. I can't move ...
6
votes
2answers
619 views

Can I query which processes (if any) are currently accessing the microphone?

I'm running Debian (technically Raspbian), trying to get a Star-Trek style voice-command system. I've got it mostly up and running, but in the interests of privacy and all that jazz, I don't want my ...
2
votes
1answer
130 views

Assigning static device path

I have 4 flash cards plugged in, sequentially named by system: /dev/sda1 /dev/sdb1 /dev/sdc1 /dev/sdd1 I want to assign static pathes to them, so every time the system boots up their pathes will ...
-1
votes
1answer
708 views

what type of device drivers are available in linux [closed]

The different types of device drivers used in linux are character device and block device. Is there another classification?