Changing the default size of gnome-terminal

Whenever I start gnome-terminal, it opens to 80 columns x 24 rows.  That is too small for my taste.  Henceforth, I want it’s default size to be 80×50.  Install gconf-editor.

sudo apt-get install gconf-editor

Screenshot from 2013-02-19 00:05:02

Start gconf-editor.  In the window on the left, navigate to /apps/gnome-terminal/profiles/Default.  In the window on the right, set default_size_colums to 80 and set default_size_rows to 50.  Be sure to select use_custom_default_size.  You are done.  Close gconf-editor.  Start gnome-terminal and try out its new size.  (ctrl-alt-t, if you are using unity desktop)

Fixing postfix and saslauthd: cannot connect to saslauthd

If you are having issues getting postfix email server to authenticate with saslauthd, your solution might be found in a missing symlink.  Remember that postifx runs in a chroot environment.

I find the following warning message in /var/log/mail.log:

 warning: SASL authentication failure: cannot connect to saslauthd server: No such file or directory

The warning message tells me that saslauthd can’t be located. The real location is /var/spool/postfix/var/run/saslauthd, but postfix is expecting to find it in /var/run/saslauthd.  Create a symlink as described below and see if that fixes your problem.

sudo ln -s /var/spool/postfix/var/run/saslauthd /var/run
sudo chown root:sasl /var/spool/postfix/var/run/saslauthd
sudo usermod -a -G sasl postfix

Be sure to restart postfix and saslauthd.

sudo /etc/init.d/postfix restart
sudo /etc/init.d/saslauthd restart

After restarting saslauthd, you should see some of the following files in /var/spool/postfix/var/run/saslauthd:

cache.flock cache.mmap mux/ mux.accept

Test using your smtp client and verify that you no long receive the previous warning message in your mail.log file.  Hopefully this was your quick fix.

Making use of pydoc web server

Just a reminder here of pydoc, the python documentation tool which comes with python.  You can access documentation on any keyword, topic, function, or module file typing:

pydoc <name>

However, my favorite use, and its most powerful feature is the builtin http server.  This makes all of the python documentation easily accessible using your web browser.  To open an http server on your local machine port 9999:

pydoc -p 9999

Then just open your web browser to http://localhost:9999/

Screenshot from 2013-01-28 17:09:09

This is a helpful resource when you are working in python.

Fixing minor (compiz) window-manager issues in Ubuntu’s Unity desktop without logging out

I’m currently using Ubuntu 12.04, the Unity desktop and the compiz window-manager.  If you notice that some of your applications stop “behaving normally” on your Ubuntu Unity desktop, it might be the fault of the compiz window manager.    I will use the phrase “behaving normally” loosely to include any of the following symptoms.

  • The nautilus menubar does not appear when the nautilus window has the focus
  • Right-clicking a file in nautilus does not bring up the usual pop-up window
  • The volume control pop-up stops working in totem movie player when selected
  • In nautilus Paste-into-folder is unexpectedly greyed out but still works 

I could go on, but generally the symptoms involve the loss of pop-up windows and menubars.

I have fixed many of these issues by doing Alt+F2, and typing:

compiz –replace

Or if you have a terminal open, then run:

compiz –replace &

I hope you find this useful.  It doesn’t require you to logout/logon and your apps continue to run.

[Solved] Unity desktop and nautilus not recognizing the Calibre application for .mobi and .epub files

Calibre is a great application for managing your ebook collections.  It recognizes many different ebook formats.  I use it as a reader for .mobi, and .epub files.

After installing calibre on my Ubuntu 12.04 box, I was annoyed to find that nautilus on the Unity desktop did not associate the calibre application with .mobi and .epub files.  In other words, when I tried to open a .mobi file, nautilus didn’t know what application to launch.  Furthermore, nautilus no longer gives you the option to right-click a file and add a custom application to handle it.  You are forced to use a static list of already known applications.

Solution 1:

There appears to be an error in the desktop launcher file for calibre.  Edit the file /usr/share/applications/calibre.desktop.



To be

Exec=’/usr/bin/calibre’ %f

and save.

Now nautilus should give you the option of selecting calibre from the list of applications.  Right click on a .mobi or .epub file and select properties.  Select the “Open with” tab and select the calibre application and click either “add” or “set as default”.

Solution 2 (creating a gnome desktop launcher) :

I’m going to show you how to create a desktop “launcher” with the basic contents required.  You can modify the name and contents as needed to suit other applications and file formats.

Create a file named calibre.desktop in your home folder under ~/.local/share/applications/ (to make this available to all uses, you would copy this file to /usr/share/applications)

Add the following to that file and save.

[Desktop Entry]
Exec=’/usr/bin/calibre’ %f
Comment=e-book manager and reader

Now go back to nautilus and right click on any .mobi or .epub file and select properties.  Click the “Open with” tab.  Select show other applications.  You should now see calibre in the list.  Select calibre and click “set as default”.

You are done.  Nautilus should now recognize calibre as the default application for opening .epub or .mobi files.

Further reading:


solved: starting conky on startup under unity (Ubuntu 12.04)

I had issues when starting conky as a startup application under the unity desktop (Ubuntu 12.04 LTS).  The problem is that conky would start in a window that was on top of everything else, rather than on the desktop underneath everything else.


The problem seems to be a timing issue.  I solved this by delaying the start of conky by a few seconds.  Use the -p option when starting conky to set a pause before actually starting conky.  I chose 10 seconds, you can play around with it and find whats works best for you.

Go to the unity dashboard and open Startup Applications, add conky and set a pause using -p.  This should start conky automatically whenever unity starts, and allow time for conky to start correctly on the desktop.


Reset a forgotten root password for your mysql database

Did you forget the root password for your mysql database?  Don’t fret.  Follow these simple steps to reset it.  You will need to have root access to your server to do this.

(I’m performing this on a debian/ubuntu server.  The redhat/fedora command for stopping/starting the mysql service will be very similar)

(1) Stop your database

$ sudo service mysql stop

(2) Start the database in a full access and full privilege mode

$ sudo mysqld_safe –skip-grant-tables –skip-networking &

(3) Logon without a password

$ mysql -u root mysql

(4) Reset the password

mysql>  update user set Password=PASSWORD(‘my_new_password”) where user=’root’;
mysql>  flush privileges;
mysql>  exit;

(5) Kill the running database and restart it as normal.

$ sudo pkill mysqld
$ sudo service mysql start

You should be able to logon now with  your new password.

Fedora 16 missing H.264 decoder plugin (fixed)

If you installed Fedora 16 and added the RPM fusion repositories and you still can’t watch .mkv videos because of a missing H.264 decoder plugin.

Totem Movie Player gives you this error message

Here is how to fix it.

You are still missing a required package.  Add the following package…and you should be good to go.

sudo yum install gstreamer-ffmpeg

However, If you need full instructions for enabling the RPM fusion repositories here they are also.   The first two lines add the necessary repositories.  The last line installs the necessary plugins for variety of video formats as well as viewing DVDs.

sudo yum localinstall --nogpgcheck

sudo yum localinstall --nogpgcheck

sudo yum install gstreamer gstreamer-plugins-good gstreamer-plugins-bad gstreamer-plugins-ugly gstreamer-ffmpeg libdvdread libdvdnav lsdvd


Alternatively, you can also install and use vlc or smplayer to view mkv videos–both can decode H.254 .