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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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
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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
223 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
410 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
460 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
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2answers
6k views

How to create /dev/null?

I successfully deleted my /dev/null. How can I restore it? The OS is Ubuntu.
0
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0answers
486 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# ...
0
votes
1answer
117 views

Applying an IO redirection&audio device example in Fedora

Here is an example I saw in a webpage which uses IO redirection to make the audio device make sound. less sound.wav > /dev/audio But I cannot do it in Fedora. It outputs the input data format is ...
11
votes
2answers
8k views

How do mouse events work in linux?

This is mostly out of curiosity, I'm trying to understand how event handling works on a low level, so please don't reference me to a software that'll do it for me. If for example I want to write a ...
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votes
2answers
8k views

ttyUSB0 permission changes after restart

I'm trying to install a device. I plug in the device which creates a ttyUSB0 file. When I open it in the program I need it for, it says the permission is denied. I type in terminal sudo chmod 666 ...
3
votes
1answer
2k views

Change the number of generated /dev/tty devices

I'm building an embedded Linux system, based on Gentoo. Using udev, all tty devices are probed with a PROGRAM stanza to determine if they are a modem. Right now the system boots up with 64 /dev/tty*. ...
9
votes
3answers
6k views

Mount printers at /dev/usb and still use CUPS

Due to a new version of CUPS, I suddenly lost the direct path to my printers that was previously available under /dev/usb/lpXXX. I used this to print directly from the command line. echo "test" > ...
4
votes
3answers
2k views

What do first column in /proc/mounts really mean in Linux?

Run cat /proc/mounts and I get this (simplified): rootfs / rootfs rw 0 0 proc /proc proc rw,relatime 0 0 /dev/sda1 / ext3 rw,relatime,errors=continue,barrier=1,data=ordered 0 0 io /etc/blkio cgroup ...
34
votes
3answers
4k 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?
3
votes
2answers
294 views

PCI configuration registers problem

I'm trying to get my new Realtek RTL-8169 NIC (over CardBus) to work, but I'm having this weird problem. My lspci -x output looks like this: [root@comp]# lspci -x -d *:8169 07:00.0 Non-VGA ...
5
votes
2answers
1k views

How can I create a direct 8khz audio pipe in Ubuntu?

I'm interested in creating musical programs like these: http://www.youtube.com/watch?v=GtQdIYUtAHg&feature=player_embedded Essentially these programs just generate sequences of integers, which ...
6
votes
2answers
998 views

What’s the difference between a “raw” and a “cooked” device driver?

Does this concept only apply to terminal drivers (which is what most sites cover) or to any driver in general?
5
votes
3answers
641 views

How to get my USB key to auto mount

I'm currently working in a command line only environment. When I plug my USB key in, I see a new device file in /dev: ... sdi sdi1 ... If I simply sudo mount /dev/sdi1 /media/tmp, and umount it ...
3
votes
1answer
385 views

Vanishing permission on device file (RHEL 6.1)

I want to set world read/write permissions on a raw block device file (yeah, I know). I can set the permission to 666, but it goes back to 660 immediately after I touch it or write to it. Why? ...
23
votes
1answer
2k views

What do the device files in /dev actually do?

(Not a duplicate of Understanding /dev and its subdirs and files) I was browsing around my filesystem and for the first time I took a second to analyze my /dev directory. I was surprised by the ...
4
votes
2answers
2k views

How does /dev/fd relate to /proc/self/fd/?

$ ls -l /dev/stdin /dev/fd/0 lrwx------ 1 tim tim 64 2011-08-07 09:53 /dev/fd/0 -> /dev/pts/2 lrwxrwxrwx 1 root root 15 2011-08-06 08:14 /dev/stdin -> /proc/self/fd/0 $ ls -l /dev/pts/2 ...
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3answers
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Understanding /dev and its subdirs and files

$ ls -l /dev/stdin /dev/fd/0 lrwx------ 1 tim tim 64 2011-08-07 09:53 /dev/fd/0 -> /dev/pts/2 lrwxrwxrwx 1 root root 15 2011-08-06 08:14 /dev/stdin -> /proc/self/fd/0 $ ls -l /dev/pts/2 ...
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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 ...
9
votes
4answers
8k views

Find out what device /dev/root represents in Linux?

On linux, there is a /dev/root device node. This will be the same block device as another device node, like /dev/sdaX. How can I resolve /dev/root to the 'real' device node in this situation, so ...
2
votes
1answer
1k views

How do I access a digital camera drive via usb after safely removing it?

In Ubuntu 11.04, I unwisely right clicked and "safely unmounted the drive" of my Sony HDR-XR150 connected via USB. Now, when I plug my digital camera into my computer via USB, Ubuntu either doesn't ...
1
vote
1answer
371 views

logical volume, logical disk, volume, partition, physical disk and filesystem

I was wondering how logical volume, logical disk, volume, partition, physical disk and filesystem are related and correspond to each other? I am confused about these concepts and would like to have ...
1
vote
4answers
4k views

cfgmgr like command under Linux?

cfgmgr is a command under AIX/ksh that checks for new hardware; e.g. new HDD's that have been added without a shutdown. Question: Are there any similar commands under Linux? If "fdisk -l" doesn't ...
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3answers
2k views

Mounting a device — role of /dev, /media and /mnt, and the mount command [closed]

I have several closely related questions about what happens when I insert a CD. The files on the CD /media/Ubuntu\ 11.04\ i386/, but from what I've seen /dev/cdrom is also involved. What is the ...
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3answers
3k views

Prevent claiming of novelty usb device by usbhid so I can control it with libusb?

I have a USB rocket launcher that I wish to experiment with through libusb. However, libusb cannot claim the interface; presumably because the output of usb-devices lists 'usbhid' as the driver for ...
10
votes
4answers
4k views

Can I setup a loopback audio device?

If I can send audio to the output devices, then I can record the same audio as a wave. With filesystems, you can just setup a loopback filesystem and write binary data on a file instead of a device. ...
5
votes
2answers
340 views

Unclaim a device

So I am using Ubuntu and trying to use some hardware which I had some problems with before. The problem before was that the company who made my hardware sold their internal parts to another company ...
25
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4answers
18k views

What is the mknod command used for?

I just started using Ubuntu as my main OS and I wanted to learn about things I should not do, and learn by the bad things people have done in the past. I came across these email about horror stories ...
5
votes
1answer
993 views

How to be notified when a USB device was plugged in?

My system has to auto-mount USB devices; how can I be notified when a USB device is plugged in? Where can I read more about this subject? I would like to handle this problem via C or a shell script. ...
16
votes
2answers
3k views

Manipulating `/dev/video`

I'd like to take the video stream from /dev/video0, apply some effects or changes and make the result available on /dev/video1. /dev/video0 ---> Apply Effects ---> /dev/video1 For example, mplayer ...
5
votes
2answers
2k views

Can I share a device from under /dev across hosts?

Here's the situation. I have a video device /dev/video0 on a VMware Server and I want to access this device from within a virtual machine. However for whatever reason I can't connect the device ...
10
votes
4answers
4k views

Shell command to read device registers?

On a single-board computer running Linux, is there a way to read the contents of the device configuration registers that control hardware? I think it would be a wrapper for inw(), more or less. I'm ...
61
votes
12answers
194k views

How do I find out what hard disks are in the system?

I need to know what hard disks are available, including ones that aren't mounted and possibly aren't formatted. I can't find them in dmesg or /var/log/messages (too much to scroll through). I'm hoping ...
4
votes
1answer
3k views

Why do my SATA devices show up under /proc/scsi/scsi?

I have 3 SATA devices on my system. They show up under /proc/scsi/scsi, although these are not SCSI devices. Why do my SATA devices show up under the SCSI directory? $ cat /proc/scsi/scsi Attached ...