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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7
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1answer
9k 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
1answer
100 views

Capturing data from a Fluke 1620a via Bash /dev/tcp file descriptor

I am currently trying to develop a script that will connect to a Fluke DewK 1620a Themo-Hygrometer and pull the current temperature and humidity readings from the device. While these devices have a ...
39
votes
4answers
5k views

Why are network interfaces not in /dev like other devices?

I'm mostly curious, but why aren't network interfaces in /dev? Are there any other kinds of devices that aren't represented as a node under /dev?
2
votes
1answer
52 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 ...
1
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0answers
45 views

FreeBSD: Permanent nodes for usb devices

In FreeBSD, USB devices appear in /dev as (for example) /dev/ugen2.5, /dev/ugen2.6, etc... However, I noticed after a reboot sometimes these are pointing to different devices. Is there a way to lock ...
2
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0answers
104 views

Why reading from and writing to framebuffer shows no effect ?

I read a very short description of how to make a Screenshot by making use of the file which represents the framebuffer /dev/fb0. in order to write the screen content: cat /dev/fb0 > file in ...
3
votes
3answers
1k views

How to know if /dev/hda2 is Primary partition or Extended partition

If all four primary partitions exist on an IDE drive, they are numbered as follows: /dev/hda1 /dev/hda2 /dev/hda3 /dev/hda4 We have also the partitions on a disk with one primary partition and ...
4
votes
2answers
1k views

Using bash's `/dev/udp`, how would I know if the port was open?

I do not have access to netcat or nmap so I'm trying to use bash and the /dev/udp/ special files to test ports. I could do something like: echo "" > /dev/udp/example.com/8000 But $? is always 0 ...
0
votes
1answer
67 views

Sunix Low Level Parallel port driver not working

Background: I am currently in the process of updating a Industrial PC + software from Debian 4 (etch) to Debian 7 (Wheezy) due to hardware obsolescence, one of the few pieces of hardware being shared ...
1
vote
1answer
122 views

Can you scp a device file?

My flash is partitioned as /dev/mtd0 /dev/mtd1 etc....And I want to scp one of the partitions over to my pc so I can analyze it with a hex editor, but everytime I try to copy it with scp I get -not a ...
0
votes
1answer
90 views

Debian Fresh Install: IO_Page_Fault

I recently tried to install Debian alongside the mint installation I am using to type this. However, I keep getting this strange error whenever I try to boot it, even after a fresh install ...
2
votes
1answer
290 views

Why is “nodev” in /etc/fstab so important? How can character devices be used for hacking?

I am learning about linux security and struggling to understand why a USB stick with a character device on it is potentially dangerous. If I have a USB stick with a bash executable that has setuid ...
1
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0answers
66 views

Suse 10 - Same disk showed as IDE (hda) and SCSI (sda)

I have a strange problem with disk detection. I installed a Suse 10 and I see the same disk (scsi) showed as /dev/hda and /dev/sda. Here the fdisk output: sl0slmkmsd00:~ # fdisk -l /dev/hda Disk ...
1
vote
0answers
107 views

Bluetooth keyboard not showing up in /dev/input

I've just installed an Apple Wireless keyboard on a Debian system. I used this guide and only console tools — no X on that machine yet. The keyboard works fine. Now I want to remap a right Cmd key ...
1
vote
1answer
1k views

Why isn't sda1 showing up in dev and how can I fix that?

I have an embedded Linux device and I was trying to copy some files to it. I plugged in a USB stick, the dmesg shows that it was recognized, but for some reason /dev/sda1 never showed up. I'm trying ...
0
votes
0answers
127 views

No USB flash drive / dev / Galileo Intel Gen2

I have intel Galileo Gen2 and Debina installed on it from here: http://sourceforge.net/p/galileodebian/wiki/Home/ And I also have a problem with that, it does not appear in the / dev / any of the usb ...
12
votes
4answers
5k views

If I connect a physical device, how can I ever know which device file belongs to it?

Say I plug in several USB drives which don't get automatically mounted. How can I find out which device file belongs to which physical device, so I can mount it for example? I'm running Mac OS X but ...
-1
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1answer
34 views

Which of the following is a Linux representation of a physical USB device?

I'm trying to figure out which of these could be a physical USB device: /dev/hda /dev/hda1 /dev/bin /dev/sda /dev/sda2 What's the difference between hda and sda? Between hda and hda1? Which could ...
1
vote
0answers
74 views

Pipe a device via USB or wlan

I have an Android phone and I want to use some of its onboard device from PC. To be more clear, there is a node in /dev/ and I want to have on PC a file (or named pipe which is accessable as a file) ...
0
votes
1answer
45 views

How to figure out primary/secondary IDE channel via sysfs (if possible)

Though I've got quite a good basic understanding of sysfs meanwhile, there are still things I cannot solve on my own. For a starter, I'd like to figure out via sysfs (later by scripting of course) ...
0
votes
1answer
253 views

RHEL7: Why does 'nmcli conn show' & 'ip addr show' display different connections?

My 'nmcli conn show' & /'etc/sysconfig/network-scripts' config files don't match up, showing just one connection/devices of each: [root@ciroc network-scripts]# ls |grep ifcfg ifcfg-enp0s3 ...
1
vote
1answer
164 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 ...
4
votes
1answer
429 views

Why did sshd delete my /dev/zero?

When I do lsof +c 0 | grep /dev/zero, I see the following two lines: sshd 19064 root DEL REG 0,4 497862 /dev/zero sshd 19064 root DEL REG 0,4 498725 /dev/zero ...
1
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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 ...
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0answers
31 views

Detecting and categorizing device drivers in a running system

How can I obtain what device drivers are incorporated in a running kernel? More than this, how can I categorize these device drivers? For instance, this is a Linux kernel conceptual map, from ...
2
votes
1answer
248 views

What are the two values in < > in a device tree .dts file?

Following is the code snippet in a device tree file: flash@0 { compatible = "n25q128"; reg = <0x0>; spi-max-frequency = <50000000>; ...
2
votes
1answer
81 views

execute chmod on boot time on headless debian

I am programming a (web based) POS system, dedicated to be running on a debian based ITX-server with apache2 etc. Currently I am using Lubuntu 14.04 LTS for development (and for the 1st customer) with ...
3
votes
3answers
5k views

Creating eth0 with consistent network device naming

From my understanding, Arch Linux uses Consistent Network Device Naming where the network devices are no longer named eth0, eth1, etc. I use the proprietary MATLAB software which requires a device ...
1
vote
1answer
26 views

Pushing changes to driver repos

My understanding of dkms is that its a way to dynamically manage all connected/disconnected device drivers on a Linux system. If that's correct, then I have to imagine that it allows you to configure ...
1
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2answers
56 views

Creating a device similar to /dev/random from a script

I am writing a program for which I will create a script to generate test data in a specific format. How can I create a /dev/myprogram device that would work similar to /dev/random (preferably in ...
9
votes
5answers
8k views

Why does “cat ttyUSB0” not produce output?

I connected an infrared receiver to a USB port ... (the last line of dmesg tells device file) $ dmesg [10496.596063] usb 7-2: new full-speed USB device number 2 using uhci_hcd [10496.751112] usb 7-2: ...
10
votes
4answers
816 views

Trouble with understanding the concept of mounting

Having read both What is meant by mounting a device in Linux? and understanding "mount" as a concept in the OS, I have a problem where it is stated that All accessible storage must have ...
44
votes
9answers
6k views

Why do we need to mount on Linux?

I understand what mounting is in Linux, and I understand device files. However I do not understand WHY we need to mount. For example, as explained in the accepted answer of this question, using this ...
19
votes
3answers
19k 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.
1
vote
1answer
85 views

Why does tapping a TTY device only capture every other character?

So, I came across the ttyname function (unistd.h) and had to test it out. #include <unistd.h> #include <stdio.h> int main(void) { printf("%s\n", ttyname(0)); return 0; } On my ...
2
votes
0answers
91 views

How to know when a device is ready

I have firewire mixing console and I wrote an udev rule which calls a script to set up the whole audio chain (alsa -> pulseaudio -> jackd -> firewire) as soon an the console is switched on. Now I ...
0
votes
2answers
36 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 ...
1
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0answers
332 views

Editing a device tree to disable driver loading

Below is a section of device tree. ps7_ethernet_0: ps7-ethernet@e000b000 { #address-cells = <1>; #size-cells = <0>; clock-names = "ref_clk", "aper_clk"; clocks = ...
1
vote
2answers
399 views

What is a device tree and a device tree blob?

What exactly is a device tree, and a device tree blob? Where can I get its source code for a particular linux version? I found such name while running linux on xilinx chips (having ARM 9), for ...
1
vote
1answer
34 views

Does programmer use device files as interface to device drivers in their programs?

In Linux shell, a user can access a device driver, via its device file as the interface. When a Linux C programmer want to access a driver in his C program, does he also access the driver, via its ...
2
votes
1answer
431 views

How can I set device rw permissions permanently on Raspbian?

I'm using the Raspbian (a distribution made for Raspberry Pi, which is based on Debian). I have some scripts that use i2c. Normally only root has read and write permissions for i2c. I'm using this ...
1
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0answers
134 views

Raspbian: USB storage device name changing after USB device power cycle

I'm running Raspbian 7.4 on a Raspberry PI that has two USB storage devices connected to it. This Raspberry PI will remain running during a power failure because it has console cable connected to it ...
1
vote
1answer
29 views

Is the directory that a file-system is mounted on (mount point) a device file of the file system's type?

A device file is an interface to the device driver of the device. When we mount a file system to a directory, is the directory considered a device file (of the file system's type)? If the ...
0
votes
0answers
68 views

Pegasus R6 Thunderbolt raid with CentOS 6.5

We have ourselves a rather expensive Mac Pegasus R6 external thunderbolt raid and a CentOS box that we would love to use it. On a Mac it's plug and play, however on our CentOS box it's not recognized ...
3
votes
3answers
284 views

How to inspect the contents of /dev/sdt?

I have what I hope is not a huge problem, but could end up being a very large problem. For some context, I mistakenly ran this command on my 27'' iMac: sudo dd if=ubuntu-rescue.img of=/dev/sdt ...
4
votes
1answer
290 views

Difference between /dev and /sys

Exactly what is the difference between devfs and sysfs? Both seem to maintain a list of hardwares attached to the system. Then why the need for 2 separate fs even arose? As far as I can get /sys ...
6
votes
1answer
435 views

Why does the UNIX system need so many [0-byte] drives at /dev/* [duplicate]

So I recently asked this question, which lead me to run this command: $ du -sk /dev/* Which outputs about 353 different entries that look like this: 0 /dev/sdt 0 /dev/stderr 0 /dev/stdin 0 ...
2
votes
2answers
2k views

Mount an ISO virtually using /dev/sr0 device

I'm doing a study about how CD-ROM can be mounted virtually and all I could find out was mounting using loop devices. mount -o loop disk1.iso /mount-point This is fairly easy. I understand that ...
1
vote
1answer
3k views

What is the difference between /dev/sda and /dev/hda? [duplicate]

Sometimes internal harddrives are available as /dev/sda (with subsequent media located in /dev/sdb etc), and other times available as /dev/hda. What is the difference between the two? Does it vary ...
7
votes
1answer
2k views

USB connect/disconnect notification

I use Linux Mint 13 MATE, and I'm trying to set up notifications when I plug/unplug devices. First of all, I found udev-notify package, but unfortunately it almost doesn't work for me: it works for ...