General :: Read From A Character Device?

Oct 5, 2009

i studied the program chardev.c from 'The kernel module programming guide'. The text tells me that by doing a :

1. 'cat' the character device is opened.

2. hi > /dev/hello the character device is written into.

now i wanted to know how to 'read' from the character device !

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General :: Use The Man / Info / Apropos Pages - Character Instructed The Shell To Interpret A Special Character As An Ordinary Character?

Mar 27, 2010

1.What character instructd the shell to interpret a special character as an ordinary character?

2.What directory contains some of the utilities available on the system in the form of binary files?

3. What command is used to search the location of a utility?

4. What command is used to instruct the editor to write the file and quit the editor?

5. What key quits the more utility and displays the shell prompt?

6. What command starts a child shell as the super user, taking on root's identity and environment?

7. Which wildcard characters can be used for searching all the files in the system that start with "A"?

8. The user name or login name of the super user is????


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General :: Serial Input Read Into A Character App?

Oct 27, 2009

I have a character app running on a Linux server with a telnet thin client. This app requires 3 input values that I would like to be filled in from a scale indicator that is connected via serial to the PC running this app. I feel like this is doable but not sure how. The app is running in Progress 10.1B. Currently I can see the 3 values coming from the serial port with hyperterminal but I do not want to have to rekey into the app.

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General :: How To Unregister A Character Device

May 17, 2010

I'm reading linux device drivers,
and I'm creating a scull-like driver.

I alloc a chrdev region

how can i deallocate it ? I tried with
unregister_chrdev_region but it does work only for
statically allocated devices.

i want to deallocate it so that only a single major number is assigned to my driver and

cat /dev/devices | grep $dev_name
returns no more than 1 line.

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Debian :: Unable To Read Japanese Character From One Day To The Other

Mar 3, 2016

From one day to the other, I can't read Japanese anymore. I could yesterday, I can't anymore, be it with firefox or chromium that I just installed ! This is madness. With one browser I have empty white square, and the other white squares containing four numbers.

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General :: Make The Root Device Read/write?

Mar 4, 2011

I need to change a filename but when I boot up I get the message root device is read-only. Is there a way of changing this so that I can change the filename. I have a Mac Pro running Leopard OSX. The graphics card an NVIDIA 7500GT or driver has failed. It was suggested elsewhere that I change the relevant kext files to filename.kext.old, which I did, now when I try to boot start in OSX I get a message in various languages telling me to restart. I have tried booting in safe mode and from original Installation CD. In Safe Mode I get the same multi language splash screen, from CD I still have the graphic card problem, screen freezes and artifacts appear. So I boot up straight into CLI by holding down CMD-S hoping to be able to change filenames back but it says device read-only.

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OpenSUSE :: Find What Device To Use For A Character Something Plugged Into USB

Apr 27, 2011

There are so many system information tools i figure that this one would be in the set. I just can't seen to find it.

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Programming :: Character Device Driver And Mknod?

Mar 31, 2010

I've a problem with character device mounting. I've a character device module code. Here is the code

Code: /* chardev.c: Creates a read-only char device that says how many times
* you've read from the dev file
#if defined(CONFIG_MODVERSIONS) && ! defined(MODVERSIONS)
#include <linux/modversions.h>


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Programming :: Character Device Driver For Communication Between Two Pc's In Code?

Apr 3, 2010

i woul like to know if i could get help in writing a charater device driver for communication between two pc's in linux using RS-232 serial port.

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General :: Usb/external Drive Problems Redux - Read-only - Does This Suggest Device Failure

May 22, 2010

I initially thought the problem had to do with the Lucid Lynx upgrade, a lot of people have been reporting similar issues with drive mapping and things along those line. My issue is that an external drive, formatted in FAT32 appears to be corrupted, and overtime begins to read or mounts as 'read-only.'

What I've read, and deduced, is that this is ultimately and issue with the drive. I've backed it up, reformatted, and been able to write to the drive successfully, but I've been moving a lot of files (backing up) and the system has been reporting input/output errors in transferring some files (through the GUI).

The only thing I can think of, is that the device itself is corrupted or damaged, and that I need to be thinking of other back-up options for the future. Any suggestions on disk-doctoring? I'm hoping to do a clean-install of the OS once I back up my files manually.

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Fedora :: Usb 2-1: Device Descriptor Read/64, Error -62

Apr 23, 2010

I tried to get 3d hardware support in my FC12 install. I grabbed the latest appropriate drivers from the nvidia website for my Geforce 6800 XT graphics card. I changed the inittab file to boot to command line, ran the .run file as root and ran into a couple errors doing so.

I then proceeded to use yum (which i do like but this is a bad scenario for me thus far) to update my drivers to the suggested kmod-nvidia drivers that exist out there. Once all of the installation was completed I rebooted and got the following error displayed at the top of my screen after the fedora loading bubble disappeared. The system just seems to hand at this point....

"usb 2-1: device descriptor read/64, error -62"

I did a hard boot on the machine and tried again, this time i pressed the esc key to watch the interactive startup screen and noticed that after "enabling local filesysem quotas: [ OK ]" i get a

***Warning -- SELinux targeted policy relabel is required.
*** Relabeling could take a very long time, depending on file
*** system size and speed of hard drives.

This will continue with asterisks across the screen until eventually it stops and then I am stuck as to what to do from here on out. What could possibly be causing all of this mayhem?I have tried to use the fedora core 12 install cd to launch it into "rescue mode" and from the bash command line proceed with modifying my grub.conf to not use the "newly installed kernel (" that was installed with yum during my kmod-nvidia driver installation.

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Programming :: Timer Of 10 Ms For Read / Write A USB Device?

Apr 13, 2011

I need programmer a timer of 10 ms for read/write a USB device

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Ubuntu :: Current Users Mounts USB Device As Read Only?

Dec 18, 2010

I am trying to add/delete files from my HTC Evo through ubuntu via enabling file sharing on the device. Ubuntu detects the drive, and mounts it up so that I can browse/read files off the device. However, I am not able to do any writing to the device because it is mounted as "read-only". The only wierd thing is that it worked last week, and I have not changed any settings on my system. Where should I start? Is the auto-mount for USB drives located in "/etc/fstab"? because here is the contents of that file, and I dont see anything for usb mounts:

# /etc/fstab: static file system information.
# Use 'blkid -o value -s UUID' to print the universally unique identifier
# for a device; this may be used with UUID= as a more robust way to name


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Hardware :: Webcam 'dummy' Device Can Only Be Read By Mplayer

Aug 13, 2009

I'm playing a little bit with OpenCV but the webcam that i have on my desktop isn't app-friendly... so i could not get it working with OpenCV, it's a 0ac8:301b Z-Star Microelectronics Corp. ZC0301 WebCam and it worked out of the box with Cheese and after a little bit of tweak i get it working with camorama also.But some apps, like Skype and OpenCV demos doesn't work, believe me, i tried everything to get it working, i tried even upgrading to a very new kernel.

So i had the idea to create a "virtual" video device and using some app that can read the wcam i could print the wcam's output on such device, which should be compatible and app-friendly, so i would use that device always.

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Server :: Mount - Block Device Giving Read Only

Mar 15, 2011

I want to keet some data on windows dir. I have tried the below command and giving the below error.
[root@xyz0044 ~]# mount -t cifs // -o username=domainv.kumar3,password=xxxx /mnt/backup
mount: block device // is write-protected, mounting read-only
mount: cannot mount block device // read-only

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CentOS 5 Hardware :: USB Device Descriptor Read Errors

Aug 20, 2010

I'm designing an embedded USB device. When I connect the device to the computer, I get the following messages:

usb 1-3: device descriptor read/64, error 2
usb 1-3: device descriptor read/64, error 2
usb 1-3: device descriptor read/64, error 2
usb 1-3: device descriptor read/8, error -71
usb 1-3: device descriptor read/8, error -71
usb 1-3: device descriptor read/8, error -71

Note that other USB devices work fine. I am fairly certain that the problem is with my hardware. I'd like info on what these error messages mean to help my debug. Searching Google I wasn't able to find any explanations about what these errors mean exactly.

I'm running Cent OS 5.4 with kernel 2.6.18-164.el5 on an i686

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CentOS 5 Hardware :: Device Descriptor Read/64, Error -110

Feb 2, 2011

I'm having issues with getting my USB ports to work on my server. USB keyboards, mice, drives, flash drives, card readers, etc. will not work on this server.

Linux version 2.6.18-194.32.1.el5 ( (gcc version 4.1.2 20080704 (Red Hat 4.1.2-48)) #1 SMP Wed Jan 5 17:53:09 EST 2011
BIOS-provided physical RAM map:


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OpenSUSE Hardware :: Finding A External USB CD/DVD Read/write Device?

Jul 30, 2011

My wife is purchasing a netbook with no internal CD/DVD writing device, so we plan to purchase an external CD/DVD USB-2.0 read/write device. Our local PC shop has the following 3 external USB-2.0 DVD read/write devices:

(a) Samsung DVD-Burner SE-S084F/RSBS [not listed on Samsung site - too old ? ]

(b) LG DVD-Burner GE24NU21 USB2.0 [not listed on LG site - too old ? ]

(c) Super-Multi Portable DVD Rewrite (GP10 Lite USB2.0 Slimline) GP10NB20 (mentions Mac OS/X support, which is encouraging)

None of those are listed in the openSUSE HCL. Has anyone successfully used any of these with GNU/Linux (my google surfing on this revealed no GNU/Linux complaint nor any success stories) ? Or is there another such external USB-2.0 read/write DVD burner device that is recommended ?

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Ubuntu :: Unable To Mount Device, Write Protected & Read Only?

Feb 17, 2011

I used dual booting with Windows Xp and Ubuntu 10.04. Because errors, I reinstall Windows and then I could not enter GRUB, and Ubuntu partition disappear. I tried to reinstall ubuntu using live CD but I could not detect last ubuntu partitions. After I installed fresh Ubuntu on new partition, I got error message like this:

Unable to mount floppy0 Mount: block device /dev/fd0 is write protected, mounting read-only Mount: could not determine the file system type, and none was specified

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Software :: In Platform \ Use Ioctl Function To Read/write Data To Hid Device?

Jun 24, 2011

Now i have a problem.I want to used a hid usb device under linux 2.6.11.But i can't know how to used ioctl function to send and receive data to a hid device

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Slackware :: Optical Drive Not Identified - Get Permission To Read / Write In The Device

Aug 6, 2010

On one of my machines the DVD/DVDRW/CDROM drive appears as /dev/hdc and is not identified as an optical drive by HAL. It is owned by root: disk and thus no users get permission to read/write in the device (not even those in the cdrom group). This stops playing DVDs, ripping CDs, no notifications appear when a disk is inserted, etc. etc. When I set the permissions for all to read/write from the device then users can access but still no notifications are shown.

On all my other machines the optical drive is identified as /dev/sr0 and is owned by root:cdrom . All have Slack 13.1 . Previously with Slack 12.2 this machine still had the drive in /dev/hdc but the permissions were right (I think because I added it to /etc/fstab with options for users to access it). I believe the problem is down to HAL not setting this drive to the correct group, but how do I fix it? I hate HAL, it has a mind of its own, just like in the scifi movie

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Ubuntu :: Frozen Panel - Messing Around With The Alternate Character Panel App And Made A Custom Character Set

Jun 12, 2011

I was messing around with the alternate character panel app and made a custom character set. I then wanted to put it on a new panel and created a new panel. I moved the character set to that panel, and then started to mess around with the panel settings (auto hide, show hide buttons, and expand, to be specific.) So far so good, until I moved the panel from the right side of the screen to the top. I already had a panel here, and it seemed not to like hiding a panel when there was already one on the top.

When the new panel hid itself, all my panels stopped responding (any clicks on them did nothing) and my processor started going at 100%. I tried a reboot and the only thing that changed is that now I can't even see my panels. I'm guessing I need to change the settings back manually through the prompt, but I don't know how to do that. I am using 10.04 and have not upgraded gnome since upgrading to 10.04.

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Ubuntu :: Fatsort - Sort_fs: Device Or Resource Busy - Cannot Read Boot Sector Or Headers

Feb 14, 2011

I have an audio recorder that doubles as a music player. It can play WAV files. So I put in some WAV files and they are out of order, even if they are named numerically. Read somewhere about a little CLI software called fatsort so I installed. The device is located at /dev/sdc. So naturally I write fatsort /dev/sdc, it says something about permission. So sudo fatsort /dev/sdc. Thing is, it says:

Code: sort_fs: Device or resource busy! If I "eject" it (unmount) then it says something about cannot read boot sector or headers. On Windows there is FAT Sorter. It does not work in WINE. So every time I put something in, I have to get to a Windows computer to sort it. It seems like fatsort is the only program that sorts FAT systems in Ubuntu/Linux.

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General :: Samba Does Not Keep Windows Attributes (read Only Files As Read Only For Example)?

Jul 16, 2011

I want my samba to keep my windows attributes exactly what the user setted in windows I mean if it has read only file in win box and copy it to samba share ,samba keep it read only and same for other attributes but it does not do it now with my configuration:Quote:

workgroup = DOMAIN
server string = File Server


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General :: VI And Vim And Set Default Character?

May 11, 2011

1,i access my server via secureCRT, when i typed the Code: vim in it, it shows Code: -bash: vim: command not found . how to install the vim? my linux version is centos.

2, when i typed some chinese characters in VI, it shows unnormal. maybe i should set the default character to UTF-8. but i don't know how to set it.

3,i want to copy a html file code to VI, how do i do?

4,how to create a file. like this? Code: mkdir filename ?how to rename the file, which i created by VI and had some contents in the file.

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General :: Sed Add A Character To The End Of Each Line

Aug 5, 2010

I am using the following command to add a comma to the end of each line in my file:

but for some reason the comma gets placed on a new line in between each line in the file. Why is this?

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General :: Bind / Map Character To Alt+?

Dec 23, 2009

In programming and various terminal programs (Screen, Vim) the [, ], { and } tends to be used a lot. I'm using a Norwegian keyboard where these are placed such that I have to stretch my fingers a bit too long for whats comfortable. To make it easier I though I'd try to make alt+[some key] be one of these characters. Is there a way that I can bind, say alt+� (Norwegian letter) to '{' system wide?Btw, is such thing called binding, mapping or something else? I'm getting a bit confused by the terms...

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General :: Cut Only 2nd Line And 2 Character?

Apr 6, 2010

i have a trouble here to cut a file

cut -c1-2 /etc/hasil.log


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General :: 567 Is A 3 Character Number Why The O/p Is 4

Jan 11, 2011

look into the following command...

asit@ubuntu:~/script$ echo 567 | wc -c

though 567 is a 3 character number, why the o/p is 4 ??

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General :: Ubuntu - Find The Device Node File For USB Device?

Aug 23, 2011

I've bought an X10 Home Automation USB interface: the CM15.

This is the information lsusb gives:

skerit@KIP-DU-SKER:~$ lsusb Bus 008 Device 002: ID 0bc7:0001 X10 Wireless Technology, Inc. ActiveHome (ACPI-compliant)

But this tells me nothing about where the device file is! How can I find that, or create one myself?

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