Joey’s Linux Scams

I’m sure by now all you Firefox aficionados have heard of a little addon extension called Greasemonkey. I’ve also seen some frustration associated with the installation and use of Greasemonkey. Since I also shared this frustration, I decided to put together this little tutorial. Leave feedback in the comments section.

Installation

We’re assuming you have a functioning copy of Firefox 1.5 or better. If not go download it here. Next you will need to install the Greasemonkey extension. Restart Firefox to complete the installation. In Firefox 2.0 there should be a button in the installation dialog box that will automagically restart Firefox and restore your session as if Firefox had never been closed. Once installed properly there will be a small Greasemonkey icon in your status bar and there will also be a menu option under the Tools menu.

Pretty neat and simple so far! However, I have a sneaking suspicion most of you have made it this far already.

Configuration

Once installed properly there is still one more important piece of setup to do. You have to set the text editor. There are a couple of ways to do this.

The nerdy way to set the text editor is to open a new tab and navigate to your about:config page. In the about:config page there will be an entry called greasemonkey.editor. Right click on this entry and select Modify. Enter the path to your favorite text editor here. In Ubuntu Linux this path is /usr/bin/gedit and for Windows losers… I mean users, the path is c:\windows\notepad.exe or whatever the path is to your favorite text editor.

The mouse clicky way to do this only works if you’ve never set the text editor before (either intentionally or unintentionally). On your freshly installed Greasemonkey, right click on the status bar icon or click on Tools > Greasemonkey > New User Script. This will open a dialog box that will allow you to select your text editor.

Note: New User Script is for WRITING scripts, NOT installing them. Unless you write your own Greasemonkey scripts, you’ll probably never click on New User Script again. If you’ve previously tried to install a .js file using New User Script, it has set that .js file as your default editor. You’ll have to use the nerdy text editor setting method mentioned above to correct this. Once you have a properly configured text editor option, clicking on New User Script will simply open the text editor. Personally I think they should rename that option Script Editor or Text Editor to avoid a lot of confusion.

Installing scripts

Installing of scripts in Greasemonkey is easy, but non-intuitive. First, remember that all Greasemonkey script filenames must end in user.js and typically they are named <script-function>.user.js. You have to surf to the script to install it. Once you do that, Greasemonkey will go ahead and install it automatically. If a file is stored on your local computer, go to File > Open File… to select and open the file. Again, Greasemonkey will automatically install the script once you’ve done this. Surf to http://userscripts.org/ to find a comprehensive and searchable list of millions of scripts.

Managing scripts

Once you have scripts installed, you be able to enable, disable, uninstall, and edit them from the Manage User Scripts dialog. To get to the Manage User Scripts dialog, right click on the Greasemonkey icon in the status bar and select Manage User Scripts…, or go to Tools > Greasemonkey > Manage User Scripts…. Once inside you can turn the scripts on and off and uninstall or edit them. You can also select an include or exlcude list for each script. To make the script apply to all websites, click on the script in the left hand column and put a * in the includes list. To make a script only work for one website, for example Google, select the script in the left hand column and put http://google.com/* in the includes list. Use the same method for the excludes list if you don’t want the script to run on certain web pages.

Conclusion

I hope that this little tutorial helps some of you out. Greasemonkey is a neat feature and sometimes and invaluable tool. Let me know if you have any suggestions for this tutorial. Have a lot of fun!

Here is a little bash script I wrote that takes your Firefox bookmarks and uploads them to your web space.

Tools

For this project you will be using the bash shell and various command line operations. And of course you will need Firefox! Bash is usually the default Linux shell. This will probably work with other shells besides bash with little or no modification.

Caveats

Buyer beware! Whenever you create a script or use one from another source, always test it in a non-production environment to insure it will do no harm. Create some test files on which to run the script and break up complex commands so that you can test each part individually. When you feel confident that you are ready to implement the script, backup all data beforehand. And if you insist on running things as root or sudo, check out this horrid tale.

Method

The first thing to do is to find your bookmarks.html file. This is usually stored in your home directory structure. On my Ubuntu system it is stored at

/home/username/.mozilla/firefox/xxxxxxxx.default/bookmarks.html

where xxxxxxxx is a random set of letters and numbers that is different for each user.

Our next task is to create some directories. I like to store my scripts in /home/username/scripts, but you can store them where ever you wish. For this script we need to create two directories, backups and logs. You can create these directories anywhere you wish, but I created mine like so.

mkdir /home/username/logs
mkdir /home/username/.mozilla/firefox/xxxxxxxx.default/backups

Now we are ready to create the script.

1  #!/bin/sh
2  #move to bookmark directory
3  cd /home/username/.mozilla/firefox/xxxxxxxx.default/
4  #create backup file just in case, backups directory must already exist
5  cp bookmarks.html backups/bookmarks.`date +%m-%d-%y_%H%M`.html
6  #append date to bottom of file
7  echo "`date`" >> bookmarks.html
8  #up the results
9  ftp -in <<EOF
10 open yoursite.com
11 user username password
12 bin
13 cd public_html
14 cd files
15 put bookmarks.html
16 bye
17 EOF
18 #remove date line from end of file
19 echo "`sed '$d' bookmarks.html`" > bookmarks.html
20 #remove old backup files
21 find backups -type f -mtime +8 -exec rm {} ;
22 #move to log file directory
23 cd /home/username/logs/
24 #create log file
25 echo "Your bookmarks were last updated on `date`" > bookmark_backup.log

I’ve commented the file, but I’ll go through the script line by line and talk about what is going on. Bash comments start with the # symbol. I recommend that you comment every script or document you write. Comments not only help other people who are looking at your work, they also help you. Sometimes what seems so clear now, may not seem clear three years down the road. I have also added line numbers for clarity of discussion and will include a non-numbered copy at the bottom of this post.

• Line 1: Every bash script starts with this line or something similar like #!/bin/bash.
• Line 3: Move to the directory where bookmarks.html is stored using the cd command. It makes things easier because I can use relative paths.
• Line 5: Make a backup copy of the bookmarks.html file in the backups directory using the cp command. I name the backup file with the current date using backticks around the date command. The backtick is usually on the key with the tilda (~). Check the date man page for more info on formating a date string.
• Line 7: Append (>>) the default date string to the end of the bookmarks.html file.
• Line 9: This line tells bash to start an ftp sesson with no interactive prompting and no auto-login. <<EOF tells bash to hang on a second while we enter more ftp commands. Bash will start executing the commands entered once it sees EOF again on a line by itself.
• Line 10: Open an FTP session on yoursite.com.
• Line 11: Log in as username with password. Note here that your password will be stored in plain text, this is not very secure so be careful.
• Line 12: Put ftp in binary file transfer mode. This helps insure the file gets uploaded correctly.
• Lines 13 and 14: Change to the directory where you want to put the file. You’ll need to create these directories ahead of time. I find this works best if you only do one directory at a time. If you don’t want your document publicly displayed, store it outside the public_html directory.
• Line 15: Upload the bookmarks.html file to the server with the put command.
• Line 16: Close the ftp session with the bye command.
• Line 17: This is the end of the EOF statement I was mentioning earlier. Bash will now execute all the commands between the two EOFs.
• Line 19: On line 7 we added a date line to the bottom of the file, now we remove it to put it back like it was. We use sed for this. See the sed man page for more information on its usage.
• Line 21: Using the find command we find all backups from line 5 that are older than 8 days and remove them. Don’t forget to do this or you’ll end up with hundreds of backup files taking up space.
• Line 23: Change to the logs directory.
• Line 25: Update the log file for this script to let us know the script completed successfully.

Conclusion

You should now be able to access the results by going to http://yoursite.com/files/bookmarks.html (or where ever you put it).

For true scripty goodness, create a cron job that automagically runs this script. I run mine twice a day at 9:53 and 21:53. Here is my crontab -l for your reference.

53 9,21 * * * sh /home/username/scripts/bookmark_backup.script

Now as promised, the script with no numbers.

#!/bin/sh
#move to bookmark directory
cd /home/username/.mozilla/firefox/xxxxxxxx.default/
#create backup file just in case, backups directory must already exist
cp bookmarks.html backups/bookmarks.`date +%m-%d-%y_%H%M`.html
#append date to bottom of file
echo "`date`" >> bookmarks.html
#up the results
ftp -in <<EOF
open yoursite.com
user username password
bin
cd public_html
cd files
put bookmarks.html
bye
EOF
#remove date line from end of file
echo "`sed '$d' bookmarks.html`" > bookmarks.html
#remove old backup files
find backups -type f -mtime +8 -exec rm {} ;
#move to log file directory
cd /home/username/logs/
#create log file
echo "Your bookmarks were last updated on `date`" > bookmark_backup.log

It seems that several people have had trouble creating cron jobs in Ubuntu. Here is a method I found that works for me. It requires sudo access.

Tools:

The only thing you’ll need is cron and a good text editor (like nano), both of which are in the default Ubuntu install.

Method:

Create a file with your job(s) in it and save it with any filename (e.g. crontab_file). Put each job on it’s own line like so:

* * * * * sh /home/userbob/script1
* * * * * sh /home/userbob/script2

Next run crontab with sudo on the file you just created. Be sure to select your username with the -u option:

sudo crontab -u userbob crontab_file

Conclusion

And that’s it. Pretty simple, huh? I hope this helps you out. Check out the crontab page at Wikipedia for help with formatting your own cron jobs.

UPDATE:

Just to clarify, you need to check out the proper notation for crontab to determine how to write your own cron jobs and make them run when you want them to.

Another clarification. You must create a file with each cron job on a separate line and then run crontab on it to make it work. You should do this as a user using the sudo command. Don’t be running scripts as root. Don’t be doing work as root. Don’t do anything as root unless you have no other choice. Just forget that root even exists. Your life will be better.

Hello truth seekers! Here is my definitive guide to converting DVD audio to ogg encoded audio files in Ubuntu Linux. This method was used in Dapper and Breezy.

Tools

I used a combination of acidrip, ffmpeg, and oggenc to do the ripping. All are available through apt.

sudo aptitude install acidrip
sudo aptitude install ffmpeg
sudo aptitude install vorbis-tools

Method

First I extracted each chapter to an avi file using Acidrip. On the Video tab I set the Codec to “copy”. On the General tab I set the audio codec to “pcm” and the gain to 18 (this can be any number, experiment to see what works for you). Then I used the preview tab to check the audio levels. Then I queued up all the chapters and started ripping.

Once the avi files were made I used the following ffmpeg command to extract the audio to a wav file.

ffmpeg -i filename.avi filename.wav

You can create a bash script to do this for you, but don’t bother because I’ve already done it.

#!/bin/sh
for i in *.avi
do
  ffmpeg -i $i `basename $i .avi`.wav
done

Once I had done this, I used oggenc to make ogg files.

oggenc -q6 filename.wav -o filename.ogg

The -q6 option sets the ogg quality to 6. Most people use 4 or 5 which are a little more lossy. I prefer a setting of 6 to give me a higher quality with a file size that is still reasonable. Here is another bash script that takes care of this step for you.

#!/bin/sh
for i in *.wav
do
  oggenc -q6 $i -o `basename $i .wav`.ogg
done

Conclusion

Now you have ogg files created from you DVD that you can edit or listen to on your ogg player. This method can also be used to create mp3 files using lame.