This is where I put interesting bits of source so I can find them again. Maybe they will be useful to you. Don’t expect consistency, documentation, bike messengers, or aspiring actors.
Gumstix wifi (wlan1: link not ready)
I just spent a long time trying to diagnose an issue with a Gumstix Overo Fire and brining up WiFi (802.11b/g) on boot. I did all the standard things (when using a desktop image, you must uninstall NetworkManager and then set up your configuration in /etc/network/interfaces. I could get a connection sometimes, but it was very unclear why it would or would not connect. So unclear that I couldn’t write a script that would bring the WiFi up on boot.
I kept getting this issue:
ADDRCONF(NETDEV_UP): wlan1: link is not ready
occasionally followed by the better:
ADDRCONF(NETDEV_CHANGE): wlan1: link becomes ready
Also, something odd was going on that I don’t understand because when the interface would configure on boot, it would rename to wlan1:
[... boot messages ...] libertas_sdio: Libertas SDIO driver libertas_sdio: Copyright Pierre Ossman Remounting root file system... libertas: 00:19:88:21:59:1c, fw 9.70.7p0, cap 0x00000303 libertas_sdio mmc1:0001:1: wlan0: Features changed: 0x00004800 -> 0x00004000 libertas: wlan0: Marvell WLAN 802.11 adapter udev: renamed network interface wlan0 to wlan1 Caching udev devnodes [...]
Finally, I found a solution: use an image from 2010. I’m using the omap3-console-image-overo-201009091145 build found here and mirrored locally here.
10/16/11
Colors in `ls`
How to make (a gumstix say) show colors for ls (assuming your login shell is bash). Edit ~/.bashrc and ~/.bash_profile to match these files:
Make sure your shell is bash (if it’s not, you can change it in /etc/passwd):
root@overo:~# echo $SHELL /bin/bash
In ~/.bashrc:
root@overo:~# cat .bashrc export LS_OPTIONS='--color=auto' eval `dircolors` alias ls='ls $LS_OPTIONS'
In ~/.bash_profile:
root@overo:~# cat .bash_profile source ~/.bashrc
10/16/11
Recursively get (or set) a property in svn
Edit: There’s an easier way to delete properties recursively:
svn propdel -R rlg:email robotlib-mydev
Use find to traverse recursively through the directory structure:
find . -type d \! -path *.svn* -exec echo {} \; -exec svn propget rlg:email {}@ \;
To print out the current directory:
-exec echo {} \;
To find only directories:
-type d
To ignore svn folders:
\! -path *.svn*
To execute the propget command:
-exec svn propget rlg:email {}@ \;
The {} is the place find puts the path and the @ at the end causes SVN to parse correctly for paths that have “@” in them.
08/12/11
Firefox 5 extension compatibility check
The old preference for disabling compatibility checks (extensions.checkCompatibility) is now gone. The new one marks the version you chose to do this at:
To re-enable your broken (but likely still working) add-ons in Firefox 5.0, add the extensions.checkCompatibility.5.0 preference in about:config:
1. Type about:config into the firefox URL bar.
06/27/11
Enable editable shortcut keys in Gnome
There used to be a checkbox for it, but it’s gone now. You can still enable the option by opening
gconf-editor
and checking the box under
/desktop/gnome/interface/can_change_accels
06/22/11
Reload udev rules without restarting udev
sudo udevadm control --reload-rules
06/17/11
Email CPU usage
Say you’re going to be out of solid contact for a while, but you’d like to monitor your CPU usage (so you can make sure to SSH in and fix something if the CPUs go idle, indicating a simulation crash.)
Solution: a quick script to email me my CPU load every hour. Then all my sessions are on screen, so I can SSH in with my phone and edit/restart what I need over 3G. If it looks bad, I’ll know to get to a real net connection ASAP.
Here’s the script (requires sudo apt-get install sendemail)
#!/bin/bash
while true; do
echo `uptime` | sendemail -f abarry@abarry.org -t abarry@abarry.org -u "Uptime report (auto)"
sleep 3600
done
05/28/11
video conversion with mencoder
With sound:
mencoder VIDEO0046.3gp -ovc x264 -oac mp3lame -o VIDEO0046.ogg
No sound:
mencoder VIDEO0046.3gp -ovc x264 -nosound -o VIDEO0046.ogg
05/6/11
Reverting to old versions in SVN
If you want to revert everything to a previous version (ie revision 72):
svn merge -rHEAD:72 .
Note the “.” at the end!
If you want to revert all local changes (ie say go back to the head revision):
svn revert -R .
Again, note the “.” at the end.
To view the diff between two versions (ie what changed between revisions 72 and 73), use:
svn diff -r 72:73 file.java
05/2/11
Resize with imagemagick
convert pic.jpg -resize 50% pic.png
or
for file in *.png; do convert $file -resize 15% thumbs/$file; done
or
convert ../task1.png -resize 300x100 task1.png
File conversion is also nice:
for foo in *.jpg ; do convert ${foo} ${foo%.jpg}.png ; done
03/21/11
Browse old revision in SVN using the web interface
Append
!svn/bc/[revision number]/
to the URL of the repository (not just any folder in the repository).
So in other words:
https://svn.csail.mit.edu/locomotion/!svn/bc/681/
03/7/11
Export Cinelerra Video to YouTube
I took me a while to figure out the best Cinelerra export settings for YouTube. I ended up going with MPEG4 and an AVI container.
03/1/11
Use mencoder to convert from recordmydesktop to dv format that cinelerra can open
mencoder -vf crop=720:576:0:0 -ovc lavc -lavcopts vcodec=dvvideo seeded-1.ogv -o scaled2/colorized.avi
crop options: width:height:x:y
where x and y are the top left coordinates of the cropping box.
03/1/11
Antialiased rings / filled circles in pygame
This shouldn’t be hard. But it is.
If you want to have a filled circle / ring in pygame you need to draw the antialiased part yourself. This is a terribly complicated way to get antialiased circles.
Unfortunately, pygame does not implement an antialiased filled circle, so you basically have to create them yourself. Also, the antialiased circles that pygame does implement seem to only antialiase to white, so they cause further problems by encroaching on the colored parts of the image.
def DrawTarget(self):
# outside antialiased circle
pygame.gfxdraw.aacircle(self.image, self.rect.width/2, self.rect.height/2, self.rect.width/2 - 1, self.color)
# outside filled circle
pygame.gfxdraw.filled_ellipse(self.image, self.rect.width/2, self.rect.height/2, self.rect.width/2 - 1, self.rect.width/2 - 1, self.color)
temp = pygame.Surface((TARGET_SIZE,TARGET_SIZE), SRCALPHA) # the SRCALPHA flag denotes pixel-level alpha
if (self.filled == False):
# inside background color circle
pygame.gfxdraw.filled_ellipse(temp, self.rect.width/2, self.rect.height/2, self.rect.width/2 - self.width, self.rect.width/2 - self.width, BG_ALPHA_COLOR)
# inside antialiased circle
pygame.gfxdraw.aacircle(temp, self.rect.width/2, self.rect.height/2, self.rect.width/2 - self.width, BG_ALPHA_COLOR)
self.image.blit(temp, (0,0), None, BLEND_ADD)
02/28/11
terminal redirection
wxProcess *process = new wxProcess(this); // by giving the process this frame, we are notified when it dies process->Redirect();
this is a bit tricky (and took 5 hours to figure out). It turns out that many systems act differently when output is redirected to a file than to a terminal. For example “ls” gives different results than “ls > t” and looking at “t”.
This is an issue for us, because the way the buffering works makes many printf statements get buffered so nothing shows up. The workaround is the program called “script” which is used to write down a script of terminal commands to a file. We can invoke it with the -c option to run a command, and act like a terminal. We then tell it to send its file to /dev/null and then capture its output through standard output redirection.
Finally, we must invoke the process with wxEXEC_MAKE_GROUP_LEADER so we can later kill it with wxKILL_CHILDREN, which causes everything to close correctly.
wxString processStr = wxT("script -c ") + m_current_dir + m_text_ctrls->Item(index)->GetValue() + (wxT(" /dev/null"));
int pid = int(wxExecute(processStr, wxEXEC_ASYNC | wxEXEC_MAKE_GROUP_LEADER, process));
02/28/11