Dropbox is a fantastic application for unobstructive synchronization of files between multiple computers running different operating systems. Everything happens seamlessly behind the scene. The more I use it the more I feel thankful to the creators and devs. Today I found out a new use of Dropbox — a simple remote control tool. All you need is Dropbox and some shell scripts.

The Scenario

Why I would have come up with such an idea? The story is: I have a PC at home which I would like to access from the lab in the institute. It is reachable only if it’s connected to the VPN network in the campus. However, the VPN connection is sometimes not very stable and could die with no reason, not to say the server will automatically terminate a connection from outside of the university every 4 hours.

Therefore I really want to find a way to remotely issue commands on my home PC (which is unreachable), let it connect to the VPN network and report the IP address to me. With Dropbox, its very easy to do.

The Solution

I create a cron job on the home PC, which checks a text file (command.txt) inside my Dropbox folder every minute, when its not empty, execute the content of the file (and clear the file). On the lab PC, I can simply put the command I want to execute into the same file — since its synchronized seconds after I made the modification, it will soon be executed at home. And for reporting IP address, I wrote a wrapper script which runs on home PC to check the VPN status after connecting and redirect the IP address information into another text file (ip.txt) inside Dropbox folder. So when I am in the lab, I put the VPN wrapper script’s name inside the command.txt, maximum a minute later, I check the ip.txt. Now I can ssh to my home PC and do what ever I want.

The Script

I put up together a script which does both the adding command and the checking-then-running command job. I call it “dbrun” which is short for “Dropbox Run”. It can be download here (right-click and save).

Installation & Usage:

1. Make sure Dropbox daemon is up and running in both systems.
2. Put dbrun in both the controlling and controlled systems. I prefer the directory ~/.local/bin.
3. Make it executable if it’s not. chmod +x dbrun
4. Create a cron job to run dbrun in a short interval (e.g. 1 min) in the controlled system. I do this by creating a file crontab inside ~/.local/etc and then run crontab ~/.local/etc/crontab. The content of the file is:

   PATH=/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/sbin:/usr/local/bin:/home/pdeng/.local/bin
   */1 *   *   *   *   dbrun

   You may have noticed since I put dbrun in ~/.local/bin, I include this directory in the $PATH environment variable. (Actually other scripts like my VPN wrapper is also there, so I have to do this).

5. Now to issue a command, run dbrun 'new command' in the controlling system, you will notice the Dropbox systray icon start animating to indicate the synchronization of the modified command.txt file. The “new command” will be executed soon in the controlled system.

The default location I use to store the command.txt file in the script is ~/Dropbox/command.txt. You can change it to whatever you like by opening the script and changing the value of cmdfile(around line 11).

Security Concern

It is possible to modify the script to let it only run filtered safe commands you selected yourself. But as long as you are not stupid enough to mark the command.txt as “shared” in your Dropbox and you don’t run the script as root, I don’t see (for now) too much danger. Maybe I am too naïve so please let me know in the comment if there is any potential security issue that I overlooked. After all, I only let it help getting my home PC reachable and SSH will be used to finish all other things afterward.

Update: I just did a quick check on Dropbox’s wiki (didn’t know about this wiki before) and there is already a similar solution for remote control. The advantages of that one is a) it has smaller granularity as it runs in a big loop and check the file every 10 seconds. b) it redirect the output into another file which can be very useful sometimes. Maybe next I should do some search in Google before writing on my own, hehe …

Today’s Lifehacker has an article about how to integrate Google’s Apps into Evolution, which reminds me I always want to integrate Remember The Milk’s task list into evolution and eventually let it show in the nice looking drop down window of the clock applet on GNOME’s panel.

It should be easy because with the latest (at least, don’t know about previous version) Evolution you can create new task list of the type “On The Web”, for which you will need a webcal URL which you can find at Remember The Milk’s Info page (Using the Settings link in the upper right corner of your RTM webpage, and you will see the Info tab).

Well if you just fill in the URL and your username, you probably will get an error about some sort of authorization problem. Here is the workaround: simply add username & password combination into the address string as seen in the picture below.

After the task list is created, you will be asked for the password again (you may want to choose remember it as well), and then you should see all the tasks in you RTM account, incomplete or completed, be retrieved from the server. And meanwhile in the drop down window of the clock applet, all incomplete task should appear.

Quite like how Evolution handled Google Calendar before, the RTM task list is, for the time being, read-only, i.e. you can only see them but not add/remove/mark as complete etc. However, for me, this is exactly where RTM plugin of GNOME Do should play its role, the integration just gives me a better way to keep an eye on the tasks.

I should say that WordPress is always my favorite blog application and now with the release of 2.7, it becomes even more awesome! That is actually what motivated me to have this blog (I’d rather say a mirror of my blogger site) created.

Some new experience about the new release: I like the new design of the admin interface particularly. The quick edit and quick post feature are also very useful. And it also makes the management of comments fairly efficient. Although I don’t remember if I have ever used the blogger-to-wordpress converting tool, this time when I tried, it worked quite good, having all the post, comments and the labels converted. The labels are imported as categories by default which resulted in a huge amount of categories. Luckily there is another nifty tool to convert the categories into tags inside WordPress. The only glitch I encountered so far is some img tags lost their src attribute after converting.

WordPress.com

As I don’t have plan to host my own blog any soon, I used WordPress.com because it saves all the fuss to setup a blog and just works for a quick start. However I miss the plugin section in the admin interface as I wanted to use Markdown to write posts.

By the way, I noticed WordPress.com also uses Amazon’s S3 service, which is suppose to provide scalability, high availability, and low latency. This should make the access to the web interface reliable in most cases. (Except in mainland China, due to the freaking stupid GFW blocking wordpress.com)

Peng.u.i.n

I don’t blog so often nowadays but having a habit to keep noting something down turns out to be very helpful sometimes: I was having trouble with the Firefox performance in Fedora 9 two days ago and I googled around for help. Eventually I found the solution from my own blog post–it feels a bit strange, but anyway it makes me keep this nice little habit.

Regarding the name, I haven’t decide what the “u.i.n” stands for. But to have my name in “penguin” feels always nice to a 24/7 Linux user and FLOSS lover. Possible answers could be:

• Peng usually is nerdy :b
• Peng utters in nonsensse
• Peng utters in nowhere
• … (more to come?)

I just don’t want to stick with any of those yet, just leave some space for imagination and let the randomness bring some fun!

I always like to have nice looking icons for my application launchers. Especially when using GNOME Do, launchers with icon smaller than 128×128 pixels looks always like shit.

So choosing a good icon theme is very important for me. I am currently using the “Gnome Brave” theme from Gnome-colors package, it provides a wide-range of scalable icons in SVG format, meaning these icons can fit into any size required.

However there are always some apps that the theme hasn’t cover, like eclipse, Netbeans etc. In this case, I have to look for good quality icons for them, which can be very hard sometimes.

I actually have been trying to find a high-res icon for my Netbeans but haven’t had any luck. But today when I searched again and came across some pictures of how Netbeans launcher looks on Mac’s dock, I saw a very large, slick icon. Then I looked into Netbeans folder and noticed there was a file with extension .icns. It turned out this is one of the icon file formats used by Apple on Mac. And luckily enough, on Linux there is an utility, icns2png which extracts the PNG
files contained inside .icns file.

If you use Ubuntu/Debian, this tool is right in the repository so just install the icnsutils package. Then by issuing the following command in a terminal, you can extract the 128×128-pixel 32-bit PNG file from the Netbeans.icns file:

icns2png -x -s 128 -d 32 netbeans.icns

BTW: if you also need an icon for Eclipse, I found one with Tango style in SVG format here: http://www.gnome-look.org/content/show.php?content=45585

And if you are curious what the app is in the screenshots, it is a new interface in development for GNOME Do, a dock implementation which also provides basic Do functionalities. It is so far the best dock I’ve ever used on Linux.

Update: I just updated the Gnome-colors theme and they include an tangoish Eclipse icon. So if you are using this theme, you can save some effort, but please notice, the one used by Gnome-colors is another version which doesn’t have the 3 horizontal stripes in design.

The new code has been pushed to their launchpad address respectively, but they won’t be compatible with the current release of GNOME Do, and not even the code in trunk can use this version. You may need them only if you are using the code from “future” branch.

There are the compiled binaries from the latest code:

• Ping.FM.dll
• RTM.dll

Old versions (which should be used with all versions except future)

• Ping.FM.dll (rev 266)
• RTM.dll (rev 271)

When you decide to checkout the code and compile them yourself, you should use the arguements -r revno:271 for RTM and -r revno:266 for Ping.FM if your target installation is not from future.

Update: David has merged the code of both RTM and Ping.FM plugin into community plugin, so you now you can also check out the code at lp:do-plugins/community.

This is my emacs color theme, adjust based on the “Sunburst” theme for TextMate which is created by Soryu.

The el file can be found here: http://p3n9.kilu.de/color-theme-sunburst.el

Just finished it, more information about it is coming soon.

Source code can be grabbed from here: http://code.launchpad.net/~do-plugins/do-plugins/community.

Compiled binary (usage: download the .dll file and put in your ~/.local/share/gnome-do/plugins-0.x.x folder and restart Do)

• For GNOME Do version 0.6.*: http://p3n9.kilu.de/do-plugins/old/RTM.dll
• For GNOME Do compiled from bzr trunk code (using the new plugin API): http://p3n9.kilu.de/do-plugins/RTM.dll

Ha, My first Youtube video

Just realized I can turn off the “converting return character to <br
/>” option at blogger’s setup page. It was a disaster for me if there
is no such a thing because I like to write the post in Markdown format
in Emacs and convert it to HTML then post. To make the content easy to
read, the lines are normall truncated into a limited length. For the
previous post, I have to connect all the lines into one line before
posting, which sounds rediculous.

From now on, no more stupid BR’s, haha!

Well, let’s first see if it works before talking too much shit.