Tagged Questions

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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3
votes
0answers
185 views

How to route one video device to multiple programs

I'd like to direct the output of a single capture card (Hauppauge PVR-150) to two programs: VLC (for streaming on LAN) and MythTV for scheduled recording. I think it's possible to do this with the ...
1
vote
4answers
5k views

Updated Fedora 18 - no sound devices, just dummy output

So, yesterday I updated the recently released Fedora 18, this has been done: Packages Altered: Updated grubby-8.20-1.fc18.x86_64 @?fedora Update 8.22-1.fc18.x86_64 ...
2
votes
1answer
83 views

Standard way to expose device file to userland applications running on an unprivileged user account?

I just finished the first version of a Linux kernel module I've written in C. The module creates a device file (/dev/wn0) that controls a USB device with three LED lights. For example, running as ...
5
votes
4answers
625 views

Testing, from a script, if audio devices are in silent?

Is there a default program where I can check if my audio devices are in silent? Edit: By silence, I mean that if there is something playing on that (not just activated or opened) Something like ...
0
votes
2answers
147 views

What files are being updated or written in /dev/sda?

root@host [/etc]# iostat -xk Linux 2.6.32-279.19.1.el6.x86_64 (host.superhostsite.com) 01/13/2013 _x86_64_ (24 CPU) avg-cpu: %user %nice %system %iowait %steal %idle ...
5
votes
2answers
1k views

Why are there so many virtual terminal devices?

I've been reading the Advanced Linux Programming book and it mentions about virtual terminals which, if I understood it correctly, it is a Linux-specific feature (not in Unix) to allow multiple login ...
10
votes
2answers
11k views

What are character special and block special files in a unix system?

How are character special files and block special files different from regular files in a Inix-like system? Why are they called “character special” and “block special” respectively?
2
votes
0answers
183 views

Connected Android device - brings the network down?

I have dealt with sensitive development under Android, and have recently decided to switch to Linux now sit under (Mint 13 - KDE). But strangely, when the Android device is connected, my network goes ...
2
votes
2answers
138 views

Why I have two /dev/sdx entries with a single disk?

In my laptop (running Linux) I have only one SSD, connected to the SATA3 port. Why I have two sdx entries in /dev directory? In particular I see /dev/sda and /dev/sdb, and /dev/sda is the SSD: # ...
3
votes
0answers
490 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 ...
8
votes
2answers
4k 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 ...
4
votes
1answer
10k views

/dev/sdb: No such file or directory (but /dev/sdb1 etc. exist)

I'm not sure what is wrong here but when running fdisk -l I don't get an output, and when running fdisk /dev/sdb # I get this fdisk: unable to open /dev/sdb: No such file or directory I'm ...
5
votes
2answers
4k views

What causes /dev/disk/by-label to be populated?

I've noticed that Linux distributions typically have a /dev/disk/by-label directory, but this isn't always the case (For example, the CirrOS Linux test image doesn't have one). What's required on a ...
3
votes
2answers
3k views

Prevent usbhid from claiming USB device

Directly related: Prevent claiming of novelty usb device by usbhid so I can control it with libusb? I want to access an RFID reader (works as HID device) from a program that uses libusb-0.1. In the ...
3
votes
1answer
1k views

How do I setup more then 10 loopback device?

From this answer the solution is to modprobe loop max_loop=64 Which makes me allowed to use 64 loopback devices then mknod -m 660 /dev/loop8 b 7 8 To create the devices. I did this for 8, 9, 10 ...
2
votes
1answer
519 views

Why are there symlinks in /dev? (LVM)

[root@SERVER ~] ls -la /dev/vg/root lrwxrwxrwx 1 root root 17 2012-10-28 10:29 /dev/vg/root -> ../mapper/vg-root [root@SERVER ~] QUESTION: Why are there symlinks? Why there couldn't be only 1 ...
4
votes
0answers
2k views

How do I find out the device node corresponding to my device in SuSE 8?

I'm forced to work with a bunch of point-of-sale systems running SuSE 8. They are my client's computers. We are stuck dealing with these old systems until they get to upgrade their whole fleet to SLE ...
3
votes
3answers
630 views

Disk size management

I am using Fedora 16. My /dev/sda2, mounted on / (root) with something like 50G got filled 100%: [foampile@~ 13:13:39]> df Filesystem 1K-blocks Used Available Use% Mounted on rootfs ...
3
votes
1answer
73 views

Is 'device' synonymous with 'drive' in Unix-like OS's?

In Unix/Linux terminology, are the words 'device' and 'drive' synonymous?
2
votes
1answer
271 views

Why slowusb and scandelay?

I'm running linux-3.4.9 compiled with genkernel, and booting from a USB HDD. I was slightly annoyed by the slow boot process, in particular, during the execution of genkernel scripts at the modprobe ...
2
votes
2answers
746 views

Chroot Risks w/ /dev and /proc

I am planning to set up a few chroot jails for some users to run/test Java applications (lets just assume each application is untrusted). Is there any risk involved with mounting /dev and /proc into ...
15
votes
2answers
2k views

bash script to detect and record mouse movements?

I need to be able to record the mouse movements every so often (every .2 of a second for example) and have them in a coordinate representation instead of a diff. I found the following script: ...
3
votes
3answers
8k views

GSM modem does not create /dev/ttyUSB file

I installed Kannel in a server, and I want to use a GSM 3G USB modem to send/receive SMS messages, as described in section SMS Centers > GSM Modem of the Kannel User Guide. I have already installed, ...
9
votes
1answer
714 views

What happens when I do “cat debian.iso > /dev/sdX”?

I'm creating a live-USB and don't understand precisely: what happens when I copy a file (or even a file system) directly to a device node (as opposed to a file system)?
0
votes
1answer
152 views

Using USB hub for keyboard and mouse in multiseat

I want to configure a 2 user multi-seat in Linux. Is it possible to configure keyboard and mouse for second seat with a USB hub on a single USB port or I need to connect each of them to a separate USB ...
5
votes
1answer
147 views

Does the suid bit have any meaning for device files?

Does the suid bit have any special meaning for device files in Linux ?
3
votes
0answers
272 views

How to know the event by looking at /dev/input/by-id

I want to access the keyboard device driver. I usually accesses it by looking at /dev/input/by-name but the event provided by it gets changed every time I log in. After searchin on the Net, I found ...
2
votes
1answer
962 views

Debian USB automount

Got my USB flash automount broken after reboot. Using Debian 6, GNOME 2 My NTFS hard disk is still mounting correctly. When i connect my Android smartphone (with SD and local drive) my messages log ...
9
votes
1answer
6k views

Understand output of `udevadm info -a -n /dev/sdb`

I plug an external HDD into my laptop. I try to find out the information by $ udevadm info -a -n /dev/sdb Udevadm info starts with the device specified by the devpath and then walks up the chain of ...
3
votes
1answer
469 views

FreeBSD: Remove symlinks in devfs

Background I have been rebuilding a small home NAS. This server represents my first 'real' foray into the world of server administration and it has taught me quite a bit already. Originally, the ...
9
votes
1answer
853 views

What driver is behind a certain device file?

Given a device file, say /dev/sdb, is it possible to determine what driver is behind it? Specifically, I want to determine what driver my storage devices are using. fdisk -l lists 2 devices: /dev/sda ...
1
vote
1answer
344 views

Do I need ephemeral storage?

I was running a small instance on Amazon EC2. I'm trying to migrate it to a micro as it requires very minimal processing power. One thing I just learned though, is that micro instances do not come ...
2
votes
0answers
58 views

Limiting write rate of a device

How does one go about limiting the write/read rate of a device, E.G., USB drive, SD card? Motivation behind this question is covered here (superuser.com).
1
vote
0answers
103 views

“nopage” method for ISA vs PCI [closed]

This is with reference to LDD3 ch. 15, section "Mapping memory with nopage". I am having trouble understanding the third paragraph on page 429. It says: Note that this implementation works for ISA ...
2
votes
0answers
65 views

What are the differences between the current Linux kernel and the Unix SVR4 kernel in terms of device drivers+i/o and virtual files systems?

Yes I realize that Linux supports many more file systems and recognizes more devices than Unix SVR4. I'm interested in what the differences are in the abstraction on top of an actual file system, or ...
5
votes
1answer
388 views

Does the kernel delete entries in /dev on an initramfs?

I have a fully custom, minimal, embedded Linux (vanilla, 3.3.8, i486, Vortex86dx) system that boots from an initramfs image. No standard distribution scripts are used, just a single rcS file that does ...
1
vote
1answer
616 views

Can I use a parallel port as a CUPS input device?

I have an old piece of a hardware that does diagnostics on medical equipment. It prints out results over a parallel port. Is there any way to have CUPS accept jobs from a parallel port and redirect ...
0
votes
1answer
264 views

Hidden ext4 partition?

Is there a way to hide an ext4 partition from e.g Thunar? And the open file/save dialog , I think they come from the same source.
3
votes
1answer
3k views

How can I uniquely identify which device is on USB `hub 6-0:1.0: port 2`?

How can I uniquely identify which device is on USB hub 6-0:1.0: port 2? I receive messages in my dmesg every now and then and I want the system to tell me which device is connected to that port. ...
10
votes
2answers
6k views

set baud speed for tty

How do I set the baud speed for a specific tty (in this case a serial port)? I tried using stty -F /dev/tty.iap ispeed 19200 But get the error Invalid argument for every speed I try (2400, 4800, ...
3
votes
0answers
597 views

Build an Affordable Linux Tablet [closed]

I have 3 young children and my wife has asked that the girls get a tablet, for basic gaming, and online web tutorials (school work usually). Has anyone created or built a good affordable Linux ...
3
votes
5answers
3k views

GNU/Linux (Debian): detecting hard-disks mappings?

Let's suppose you have two hard-disks: one internal (boots GNU/Linux); one external (USB). "fdisk -l" detects both, but will not tell you which is /dev/sda and which is /dev/sdb. "lsusb" will tell ...
0
votes
0answers
137 views

problem exporting /media as an nfs share: why does it happen?

I've got two netbooks. One netbook has two installed Linux systems: openSUSE 11.04 and Debian testing. By default, in Debian, gnome mounts the /home filesystem for openSUSE, which shows up in gnome's ...
15
votes
3answers
3k views

Monitor what is being sent to /dev/null?

Just for fun: Is there a way to monitor/capture/dump whatever is being written to /dev/null? On Debian, or FreeBSD, if it matters, any other OS specific solutions are also welcome.
2
votes
1answer
218 views

Is there any way to control the light value of the Apple logo on a MacBook?

I'd like to mess around a bit with controlling the Apple logo on the outside of my MacBook Pro from Ubuntu. (I'd like to hook it up to my music and have it light up and down with the decibels :]) ...
1
vote
1answer
2k views

What's the difference between 'no caching page mode present' and 'assuming drive cache. write through.'

Post-POST, post-BIOS screen, post-GRUB; when I boot Debian with a SD card or USB stick plugged in, one of the first things to pop up on the screen (so quickly that usually I don't even notice) looks a ...
2
votes
1answer
404 views

udev weirdness: /dev/hda1 mounted but file not present

I think my question is related to udev and/or udisks, but I am really not sure at all what's going on here. To start with, my system works more or less fine. The less part is due to the fact that, ...
3
votes
2answers
456 views

Choosing a device name under /dev from the kernel command line

I am booting CentOS via a USB install. The boot method is simply booting the ISO from GRUB2 installed on the USB Key. The USB key always gets the "name" /dev/sda. Can I change that name from the ...
23
votes
2answers
6k views

How to create /dev/null?

I successfully deleted my /dev/null. How can I restore it? The OS is Ubuntu.
0
votes
0answers
480 views

Silicon Wave USB Bluetooth Adapter doesn't work

I have been trying to use my usb bluetooth adapter(silicon wave) on ubuntu 11.10 server, it appears in the lsusb list but it doesn't work Bus 005 Device 003: ID 0c10:0000 root@i5-PC:/home/john# ...