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3
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2answers
1k views

Linux : Major and Minor device numbers

What types of devices fall under the major device number category and what types of devices fall under the minor device number category. What is the real difference between the two categories?
6
votes
1answer
4k 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, ...
7
votes
2answers
1k views

wlan number assignment

How or where does Linux determine the assignment of a network device? Specifically, wlan0 or wlan1 for wireless USB devices. I plugged in a TP USB wireless a while ago, and it was assigned wlan0. I ...
3
votes
2answers
216 views

Automated partition selection in bash script

I'm trying to write a bash script to run from Linux on a CD or flashdrive that can mount Windows and change stuff, but I don't know how to go about detecting which partition/drive is Windows. My best ...
7
votes
2answers
5k views

How does cat know the baud rate of the serial port?

I regularly use cat to view debugging information in the console from my FPGA development board over the serial connection, but I never have had to tell linux what the baud rate is. How does cat know ...
3
votes
2answers
2k views

How to grant non-root user access to device files

I have device file that appears in /dev when a specific board is plugged in. The read and write operations to it work just fine, but in order to open the device file the program needs to be executed ...
0
votes
1answer
146 views

programming an Atmel Board with a USB to Serial converter, in Eclipse

I am actually trying to program an Atmel Evk1100 board directly from Mac OSX. My MCU is UC3A0512 I used to use Atmel32 Studio on Windows, but It looks like there no Mac Version. So, from what I've ...
2
votes
1answer
242 views

open() console for default file descriptors

I'm reading a shell program implementation in C ( the xv6 shell from MIT's 6.828 Operating System Engineering course ). The main() function for this shell starts with the following code: //Assumes ...
2
votes
0answers
132 views

Block Devices & Partitions

I partitioned a microSD card (mmcblk1) into two partitions mmcblk1p1 and mmcblk1p2. If use a dedicated card reader I am able to see the entire SD card and its partitions using various disk management ...
1
vote
2answers
175 views

Perform an action when a wireless keyboard is connected

I need to perform a command when I connect a bluetooth keyboard. How can I 'listen' this event?
0
votes
0answers
21 views

How to associate device to sata port disk [duplicate]

I have 2 hard disks connected to 2 sata ports. The disks are associated to /dev/sda and /dev/sdb. These hard disks are in software raid so it happens that the system can go for some time with only ...
2
votes
0answers
169 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 ...
1
vote
1answer
203 views

A drive changes device file name after resuming from suspend (Linux Mint 14)

I'm running into a very odd problem: When I resume Mint 14 from suspend, one of my drives (/dev/sdc) changes letter / device file name (to /dev/sdd). fdisk -l shows that it has the same partitions, ...
2
votes
2answers
382 views

Why doesn't xsetwacom work from udev?

I made a script to rotate my Wacom Bamboo tablet 180 degrees. It works fine when I execute it as myself (user) or root, but when started from udev (i.e. when plugging the tablet into a usb port) it ...
0
votes
2answers
70 views

Changes to files don't show up until the partition is unmounted

I have a FAT32 filesystem mounted. After changing a file on it, I can read the file back and still see the old version. My changes don't actually persist until I unmount and remount the partition. Is ...
2
votes
1answer
118 views

What is the source of truth for currently active tty/pts connections?

I'm looking for a simple way to determine the number of currently logged in users, using only the filesystem and basic bash functions (instead of using binaries). The uptime binary appears to be ...
5
votes
1answer
2k views

Writing /dev/random to file?

If you ran the following, what would happen? cat /dev/random > ~/randomFile # don't run Would it be written until the drive runs out of space, or would the system see a problem with this and ...
0
votes
1answer
515 views

remove /dev/mapper/fedora-root and /dev/mapper/fedora-swap

I want to replace Fedora 18 with Ubuntu but I have these devices listed when partitioning. I only have a hard disk labelled sda, where does these virtual device come from? How I do remove them?
4
votes
1answer
1k views

Query USB current

How can I obtain information about the amount of current negotiated by a device attached to a USB port? I am looking for information similar to this presented by OS X in terms of current available ...
0
votes
2answers
322 views

Problem mounting my iRiver story HD on Ubuntu

I would like to connect my iRiver Story HD to my ubuntu 12.04 machine but as I connect it I get this error: Unable to mount Story HD Error mounting: mount: wrong fs type, bad option, bad ...
3
votes
0answers
162 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
74 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
479 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
139 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 ...
4
votes
2answers
945 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 ...
7
votes
2answers
8k 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
168 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
127 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
370 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
3k 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
7k 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
2k 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
439 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
1k 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
499 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
72 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
248 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
643 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 ...
14
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
7k 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
674 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
137 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
143 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
243 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
852 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 ...
7
votes
1answer
5k 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
440 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 ...