Monday, January 20, 2014

Nonsensical minor long-running bug in Ubuntu

The file containing a default Ubuntu wallpaper is still named 'warty-final-ubuntu.png' (in honor of the first Ubuntu release, 4.10 "Warty Warthog"), but this PNG image actually became a JPEG one sometime in 2008!
The following "bug" still affects the "ubuntu-wallpapers" package versions found in the current Ubuntu stable (13.10 "Saucy Salamander") and development release (14.04 LTS "Trusty Tahr") repositories:
Nobody cares. Enjoy! :)

Friday, December 27, 2013

Cool method to test analog & digital (DVB-T) TV receivers?

There seems to be a cool unconventional method to test your analogue (PAL / SECAM) or digital (DVB-T) TV receiver (set-top box, unit, tuner etc.);
all you need is a PC running Linux with X11 and a video card with analog VGA output (preferably not very old one),
just read the following article (by Fabrice Bellard, 2005):
(I've not tested it personally yet, but it looks promising enough).

Monday, November 25, 2013

dd utility: the rescue versions

Apart from the traditional implementations of a Unix dd utility (e. g., one found in the GNU Core Utilities), there are some special versions of it, dedicated for rescuing the data from damaged (badly readable) disks:
  1. GNU ddrescue (by Antonio Diaz Diaz);
    seems to be the best choice from these two ones [1, 2];
    there's a GUI log viewer for it (ddrescueview), and also some other helper utilities (ddrutility);
  2. dd_rescue (by Kurt Garloff);
    there's also a wrapper script for it called dd_rhelp.
The Debian distribution software archives, starting from version 7.0 ("Wheezy"), have only the GNU ddrescue; you can install it the following way:
# apt-get install gddrescue
The convenient way to use this utility is to make an image (a binary dump) of the whole defective disk (FDD, HDD, CD, DVD etc.) with its help, and then apply data recovery / content extraction programs (e. g., TestDisk) directly to the disk image.

Anyway, regular backups & redundant data storage solutions should save you from data recovery problems :-)

  1. Disk drive recovery: ddrescue, dd_rescue, dd_rhelp - System Administration Bits of Knowledge (by John Gilmore)
  2. Damaged Hard Disk - CGSecurity
Last updated: 2013-12-08

Tuesday, October 8, 2013

Seagate: download finder

Just in case you're looking for downloads for your Seagate product (i. e., HDD firmware updates, manuals & software), here's a useful link:

Friday, October 4, 2013

MS Windows installation on Sun / Oracle computer with SPARC CPU (video tutorial)

MS Windows XP & 7 (and more): installation on Sun Fire V240 server (with UltraSPARC IIIi CPU) — video tutorial (in Russian) :-)

Monday, September 30, 2013

LCD display optimized video mode: CVT-R & Linux

Many modern LCD displays (ones with 60 Hz vertical refresh frequency) should support an improved video mode with reduced blanking intervals (CVT-R), which can save some signal bandwidth and reduce the cost of the cabling (sometimes you can use a single-link DVI / HDMI cable instead of a dual-link one to support some of the high-definition resolutions; due to reduced signal bandwidth, a longer, cheaper cable with a non-perfect shielding can be used with reduced risk of electromagnetic interference).
Unfortunately, the best mode sometimes can be missing from the display's EDID ("extended display identification data" accessed by computer through DDC), so your computer won't be able set the best mode automatically, and you'll need to do some manual configuration.
(The sample commands are for Debian GNU/Linux 7.0 "Wheezy", but should work for many other systems).
  1. First of all, find out the native resolution (e. g., 1920 x 1080) and refresh rate (should be a multiple of 60 Hz: 60 Hz, 120 Hz etc.) for your display.
  2. Try to calculate a suitable video mode string using cvt utility (from the xserver-xorg-core Debian package); 60 Hz is the default refresh rate, so it can be omitted:
    $ cvt -r 1920 1080
    # 1920x1080 59.93 Hz (CVT 2.07M9-R) hsync: 66.59 kHz; pclk: 138.50 MHz
    Modeline "1920x1080R"  138.50  1920 1968 2000 2080  1080 1083 1088 1111 +hsync -vsync
    $ cvt -r 1920 1080 120
    # 1920x1080 119.88 Hz (CVT) hsync: 137.14 kHz; pclk: 285.25 MHz
    Modeline "1920x1080R"  285.25  1920 1968 2000 2080  1080 1083 1088 1144 +hsync -vsync
  3. Check the current video mode of your display through the display's menu (and write down those values somewhere for reference). If the actual clock values are higher than calculated by cvt, then it's reasonable to test the freshly calculated video mode.
  4. For quick video mode changes, you can use xrandr utility (from the x11-xserver-utils Debian package):
    $ xrandr
    Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 8192 x 8192
    DVI1 connected 1366x768+0+0 (normal left inverted right x axis y axis) 456mm x 123mm
       1920x1080      60.0*+ 
       1024x768       60.0  
       800x600        60.3     56.2  
       640x480        59.9  
    VGA1 disconnected (normal left inverted right x axis y axis)
    HDMI1 disconnected (normal left inverted right x axis y axis)
    $ xrandr --output DVI1 --mode 800x600
    $ xrandr --newmode "1920x1080R"  138.50  1920 1968 2000 2080  1080 1083 1088 1111 +hsync -vsync
    $ xrandr --addmode DVI1 1920x1080R
    $ xrandr --output DVI1 --mode 1920x1080R
  5. For permanent effect, you'll need to change X11 settings by putting the generated modeline into the proper section of the /etc/X11/xorg.conf config file:
    Section "Monitor"
        Identifier     "Monitor0"
        VendorName     "Vendor1"
        ModelName      "Model2"
        HorizSync       30.0 - 150.0
        VertRefresh     50.0 - 160.0
        Option         "DPMS" "true"
        Modeline       "1920x1080R"  138.50  1920 1968 2000 2080  1080 1083 1088 1111 +hsync -vsync
    Section "Screen"
        Identifier     "Screen0"
        Monitor        "Monitor0"
        DefaultDepth    24
        SubSection     "Display"
            Depth       24
            Modes      "1920x1080R"
    Don't forget to restart the X server for updated configuration to take effect.
  6. The video mode for Linux console probably can be changed using KMS (kernel mode setting); there's some good info about KMS settings on nouveau Wiki.

See also:

Saturday, August 31, 2013

HOWTO: configure the OS to use a 100 Hz refresh capable CRT monitor in Linux

  • Test environment.
    • Hardware
      • Monitor: Samsung SyncMaster 959NF
        • Test display resolution: 1024 * 768 @ 100 Hz
      • Video card: based on Nvidia GeForce2 MX400
        $ lspci | grep -i nvidia
        01:00.0 VGA compatible controller: NVIDIA Corporation NV11 [GeForce2 MX/MX 400] (rev b2)
      • CPU: x86-compatible (some old AMD Athlon one)
    • Software
      • OS: Debian GNU/Linux 7.0 "Wheezy" / i386
      • Video driver: nouveau
  • X11 graphical mode configuration.
    1. Use cvt utility to generate a modeline for X11:
      $ cvt 1024 768 100
      # 1024x768 99.97 Hz (CVT) hsync: 81.58 kHz; pclk: 112.25 MHz
      Modeline "1024x768_100.00"  112.25  1024 1096 1200 1376  768 771 775 816 -hsync +vsync
      Note: 100 Hz is a non-standard refresh rate for CVT.
      If CVT timings don't work for some ancient monitor, you can also try to use gtf utility to generate somewhat older GTF timings:
      $ gtf 1024 768 100
        # 1024x768 @ 100.00 Hz (GTF) hsync: 81.40 kHz; pclk: 113.31 MHz
        Modeline "1024x768_100.00"  113.31  1024 1096 1208 1392  768 769 772 814  -HSync +Vsync
      Both cvt & gtf utilities are part of xserver-xorg-core Debian package.
    2. Change X11 settings by putting the generated modeline into the proper section of the /etc/X11/xorg.conf file:
      Section "Monitor"
          Identifier     "Monitor0"
          VendorName     "Samsung"
          ModelName      "SyncMaster"
          HorizSync       30.0 - 110.0
          VertRefresh     50.0 - 160.0
          Option         "DPMS" "true"
          Modeline       "1024x768_100.00"  112.25  1024 1096 1200 1376  768 771 775 816 -hsync +vsync
      Section "Screen"
          Identifier     "Screen0"
          Monitor        "Monitor0"
          DefaultDepth    24
          SubSection     "Display"
              Depth       24
              Modes      "1024x768_100.00"
    3. Restart the X server for updated configuration to take effect.
  • Here are the sample settings for non-X11 user interfaces, put into /etc/default/grub (the GRUB2 config).
    For modified settings to make effect, don't forget to execute update-grub2 as superuser and then reboot.
    # The resolution used on graphical terminal
    # note that you can use only modes which your graphic card supports via VBE
    # you can see them in real GRUB with the command `vbeinfo'
    1. The Linux command line option mentioned aboves allows to set a desirable video mode for virtual console using kernel mode setting (KMS).
      There's more info about KMS settings on nouveau Wiki.
    2. Display refresh rate doesn't seem to be specifiable for GRUB bootloader graphical mode. This initial graphic mode depends heavily on VBE.
    3. Other caveats: video play in console framebuffer (i. e., using mplayer) has not seemed to work for me in this test setup.

See also:

Sunday, August 4, 2013

HOWTO: get a high-quality image from an eBay listing

Well, sometimes you can find an interesting item on eBay, and then you want to take a nice look at the photos. Unfortunately, the pictures are often displayed in a low resolution (and without a "zoom in" option). Luckily, often you still have a chance to get good quality images (with resolutions up to 1600 * 1200; it depends on the quality of a picture the seller has uploaded).
  1. First of all, copy an URL of the needed image; you'll get something like this:$GaRb4gE~~60_12.JPG
  2. Then you'll need to modify the URL a little; just replace the last number found in the URL (it's preceded by a '_' and followed by a '.'; in this sample, it's "12") with "10":$GaRb4gE~~60_10.JPG
    or with "57" (I don't know what's actually better):$GaRb4gE~~60_57.JPG
  3. Just paste the modified image URL into your browser's address bar and enjoy!

  1. getProductDetails : thumbnail How can I get high resolution picture of catalogued item. - eBay Developer Support / Customer Help
Last updated: 2013-09-18

Thursday, July 18, 2013

TestDisk & PhotoRec: nice tools to recover lost partitions & files

TestDisk + PhotoRec is a nice toolset to recover lost disk partitions (or at least rescue some files from corrupted filesystems) in case of storage media failures, re-partitioning errors etc.
Works for disk images too.
More to say, it's a free & open source (GPL v2+) cross-platform (Linux, *BSD, Apple Mac OS X, Oracle / Sun Solaris, MS-DOS, MS Windows) software.

Presently, in Debian-based Linux distros, TestDisk & PhotoRec have been packaged into a single testdisk package, so you can install both tools at once:
# apt-get install testdisk