General dumping ground for computer-related notes

To convert video formats: ffmpeg -i foobar.avi -s 320×240 -r 23.98 output.avi

-s 320×180 for wide screen

The -r 23.98 is to fix this error: Seems stream 0 codec frame rate differs from container frame rate: 23.98 (65535/2733) -> 23.98 (23976024/1000000

which usually causes this one: Error while opening codec for output stream #0.0 – maybe incorrect parameters such as bit_rate, rate, width or height

Also handy is cpu frequency throttling or scaling, needed to keep my thinkpad T41p from overheating and automatically shutting down: First, change the governor to “userspace” us ing the gnome CPU frequency scaling monitor. Then, as root, do: echo 1100000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed

For some reason this is 1.2 Ghz, but close enough. Maybe an SI units vs Gibi style units issue? But it works. Cpu temp pegged at 73 celcius instead of hitting 90+ and overheating at the full 1.7Ghz this machine runs. More information at this link.


25 December 2007

To get Fedora 8 liveCD to boot on a Thinkpad T61p: Since the video won’t work, hit tab at the boot menu to edit the entry and add a 3 to set the runlevel. This prevents X from starting. Then issue:

system-config-display –set-driver=vesa, and then startx. Then it will run, and the installer should work as well.

When you boot into the new system you will again have to add a 3 on the kernel parameters line and run system-config-display –set-driver=vesa. Then run startx or gdm. When you log in you can then run system-config-display graphically and select a generic LCD panel 1900×1200. Log out and when gdm makes X come back you should be in business.


5 January 2008

To enable emacs key bindings in gnome and firefox:
gconftool-2 –set /desktop/gnome/interface/gtk_key_theme Emacs –type string

(found at mozillazine.)


5 March 2008

To batch covert a bunch of flac files to mp3:
for file in *.flac; do $(flac -cd “$file” | lame -h – “${file%.flac}.mp3″); done

(found at


19 March 2008

To remove emacs splash screen/startup screen:
(setq inhibit-splash-screen t)

Or, by using the “customize” system:
M-x customize-variable inhibit-splash-screen

(found at and others)
30 June 2008

To tunnel through the firewall and run vnc:

ssh -f -N -L 5901:localhost:5901 -X
vncviewer localhost:5901

Voila: VNC connection, secured by SSH. When you are done just
(found on slashdot)

killall ssh


Note that 5901 means the :1 VNC session, 5902 means :2, etc.

11 July 2008
If a linux system comes up in single-user mode and STILL won’t let you edit things (filesystem is READ ONLY, even if the output from mount tells you rw) try

mount -o remount,rw /

(found at
31 July 2009
Fix for firefox being really slow on DNS lookups: Enter
in the location bar. Then find the key network.dns.disableIPv6 and set it to true.
This disable IPv6 lookups which usually don’t work, at least not way back in 2009.
(found at WilksNet Tech Blog. Thanks!)

23 August 2011
To edit pdf files by putting text on top of them use flpsed.


1 June 2012

Getting this error with virtual machine using virt-manager:

Error starting domain: internal error Network 'default' is not active.


So here is how to fix that:

sudo virsh net-start default
sudo virsh net-autostart default


14 July 2010:  unetbootin is a really useful tool for making bootable USB sticks from linux ISO images.


22 January 2014:   To get LaTeX formulas in Inkscape on Fedora, you need to pstoedit package installed.  Then extensions->render-latex formula will be there.  Fix found on

Update 15 July 2015: May also need
sudo ln -s /usr/lib64/pstoedit /usr/lib/pstoedit
found on

25 June 2015:

Sometimes firefox will come back with:

**Secure Connection Failed** The connection to <whatever> was interrupted while the page was loading. The page you are trying to view cannot be shown because the authenticity of the received data could not be verified. Please contact the website owners to inform them of this problem.

Sometimes it will give a button to add a security exception, other times nothing.  When this happens you can get it to work by falling back to an older version of the security protocol.  Type “about:config” into the url bar and hit enter.  Agree that you’ll be careful.  Then search for the setting security.tls.version.fallback-limit and decrease the value by 1 (or more, if 1 doesn’t work).

answer found at: