Monthly Archives: September 2007

Play videos within *.rar files without unpacking/extracting them in Ubuntu

If you have downloaded some video and it’s packed in multi-volume archive, you can play the file without unpacking.
This is how you do it in Ubuntu. It should work fine on any linux distribution.
You wil need “unrar” and “vlc” or any other video player.

So, in Ubuntu, open a terminal and install these packages. Skip this step if you have allready installed the “unrar” and “vlc” packeges.
sudo apt-get install unrar vlc

Then issue the fallowing command:
unrar p -inul /example/path/to/Some.Scene.Release/some.sr.r00 | vlc -
What the command does:
unrar = starts unrar
p = outputs the extraction data of the file
-inul = disables error messages
/example/path/to/Some.Scene.Release/some.sr.r00 = path to one of the scene release’s rar files
| vlc – = pipes the output of the extraction into vlc that starts to play the output, and therefore plays the video file that is within the rar files. Don’t forget the ending “-“, or it won’t work. You can use another video player if you want, just replace “vlc” with what you want. I have only tested this with vlc and mplayer.

One bad thing with this trick is that you can only pause and play the file, but not rewind or fast forward.

Clean up Ubuntu!

Clean up Ubuntu!
How to clean up your Ubuntu.

01. Getting rid of Residual Config packages

In Synaptic Package Manger, there is a built-in feature that gets rid of old
Residual Config packages. Residual Config packages are usually dependency
packages that are left behind after you uninstall a package from your machine.
To use this feature, go to System > Administration > Synaptic Package Manager.
On the bottom left hand corner of the window, click the Status button. In the
list above the Sections, Status, Search, and Custom buttons, you should see the
following text:

Quote:

Installed
Installed (local or obsolete)
Not installed
Residual config

Click on the “Residual config” text. (If the “Residual config dialogue does not
appear, that means you do not have any Residual Config packages on your machine
and you can skip this step.) Do you see the packages that popped up in the
window on the right? Those are the Residual Config packages. To get rid of these
pests, click on the box to the left of the package name and select “Mark for
Complete Removal”. After you have done that for all of the Residual Config
packages, look at the top of the Synaptic Package Manger window. Do you see the
green check mark with the text “Apply” right under it? Click that button, and
you’ll flush all those Residual Config packages down the toilet!

02. Getting rid of partial packages
This is yet another built-in feature, but this time it is not used in Synaptic
Package Manager. It is used in the Terminal. To access the Terminal, go to
Applications > Accessories > Terminal. Now, in the Terminal, key in the
following command (or you can just copy and paste from here):

sudo apt-get autoclean

Enter your password when prompted and press Enter. See the package names that
appeared in the Terminal? Those were partial packages that have just been
deleted. Say goodbye! That’s it! This command deletes the
not-so-fully-downloaded packages that you acquire when a package that is being
downloaded is suddenly cancelled. This is my favorite little trick when it comes
to getting rid of junk files.

03. Getting rid of unnecessary locale data
For this tip, you need to download the “localepurge” package found in Synaptic
Package Manager. “localepurge” is just a simple script to recover diskspace
wasted for unneeded locale files and localized man pages. It will automagically
be invoked upon completion of any apt installation run.

To open Synaptic Package Manager, follow the instructions in step 1. After
opening up Synaptic Package Manager, click the Sections button on the bottom
left hand corner of the window, if it is not already clicked. Next, at the top
of the Synaptic Package Manager window, click the Search button. In the search
window, key in the following text :

localepurge

Did the “localepurge” package popup in the package window? It probably did,
unless you do not have the correct Repositories. Now, click on the box next to
the “localepurge” package name. Click on Mark for Installation. Now click the
Apply button at the top of the window and wait for the downloading and
installing of the “localepurge” package to finish. Once it is done, a new window
should popup that has a bunch of abbreviations on it. for example:

en
fr
po
sp
ka
etc...

You want to select the abbreviation of the language that you speak, or use with
Ubuntu, ignoring the capitalized ones. For example, I speak english, so I would
select the “en” abbreviation. A french speaker would select the “fr”
abbreviation. So on and so forth… Then click next. All done!

04. Getting rid of “orphaned” packages
For this tip, you need to download the “deborphan” package found in Synaptic Package Manager.
“deborphan” finds “orphaned” packages on your system. It determines which packages have no
other packages depending on their installation, and shows you a list of these
packages. It is most useful when finding libraries, but it can be used on
packages in all sections…

To open Synaptic Package Manager, follow the instructions in step 1. After
opening up Synaptic Package Manager, click the Sections button on the bottom
left hand corner of the window, if it is not already clicked. Next, at the top
of the Synaptic Package Manager window, click the Search button. In the search
window, key in the following text :

Quote:

deborphan

Did the “deborphan” package popup in the package window? It probably did, unless
you do not have the correct Repositories. Now, click on the box next to the
“deborphan” package name. Click on Mark for Installation. Now click the Apply
button at the top of the window and wait for the downloading and installing of
the “deborphan” package to finish. Once that is done, open up the Terminal.
Instructions for doing that are located in Tip #2. After you have gotten the
Terminal open, key in the following command (or copy and paste from here):

Code:

sudo deborphan | xargs sudo apt-get -y remove --purge

Enter your password when prompted and press Enter. See the package names that
appeared in the Terminal? Those were orphaned packages that have just been
deleted. Say goodbye! This is my second favorite way of dealing with junk files.

05. Adding a “Find orphaned packages” to Synaptic Package Manager
This is not really much of a tip on how to get rid of junk files. It’s more like
adding a “deborphan” shortcut to Synaptic Package Manager so that you don’t have
to use the Terminal to find “orphaned” packages.

Please note: You must have the “deborphan” package installed or else this will
not work.

To start this out, open up Synaptic Package Manager with the instructions from
step 1. Now, at the top of the Synaptic Package Manager window, click the
Settings button, followed by the Filters button. In the Filters window, on the
bottom left hand corner, push the New button. You can name the new Filter if you
like, but it is not necessary. I named mine “Orphaned”. With your new Filter
selected, in the “Status” tab on the right, click the Deselect All button. Next,
check the “Orphaned” option under the “Other” category. Then click the OK
button.

To use this new filter, click the Custom button on the bottom left hand corner
of the Synaptic Package Manager window. You should see the following text, or
something similiar :

Quote:

Broken
Marked Changes
(Whatever you named your "deborphan" Filter)
Package with Debconf
Search Filter

Click on the “(Whatever you named your “deborphan Filter)” text. Do you see the
packages that popped up in the window on the right? Those are the “orphaned”
packages. To get rid of these buggers, click on the box to the left of the
package name and select “Mark for Complete Removal”. After you have done that
for all of the “orphaned” packages, look at the top of the Synaptic Package
Manger window. Do you see the green check mark with the text “Apply” right under
it?
Click that button, and you’ll get rid of all the “orphaned” packages forever.

Rebuilding the font cache

If you install a new font in linux, you need to rebuild the fonts cache:
sudo fc-cache -f -v

How-To create a MySQL database and set privileges to a user

MySQL is a widely spread SQL database management system mainly used on LAMP (Linux/Apache/MySQL/PHP) projects.
In order to be able to use a database, one needs to create: a new database, give access permission to the database server to a database user and finally grant all right to that specific database to this user.

This tutorial will explain how to create a new database and give a user the appropriate grant permissions.

For the purpose of this tutorial, I will explain how to create a database and user for the music player Amarok. In order to index its music collection, Amarok quand use a mysql backend.

The requirement for this set up is to have access to a database. We are going to create a database called amarok which will be accessible from localhost to user amarok idetified by the password amarok….
Obviously, we need to to have a mysql server installed as well as amarok:
sudo apt-get install mysql-server amarok

On a default settings, mysql root user do not need a password to authenticate from localhost. In this case, ou can login as root on your mysql server using:
mysql -u root
If a password is required, use the extra switch -p:
mysql -u root -p
Enter password.
Now that you are logged in, we create a database:


mysql> create database amarokdb;
Query OK, 1 row affected (0.00 sec)

We allow user amarokuser to connect to the server from localhost using the password amarokpasswd:

mysql> grant usage on *.* to amarokuser@localhost identified by 'amarokpasswd';
Query OK, 0 rows affected (0.00 sec)

And finally we grant all privileges on the amarok database to this user:

mysql> grant all privileges on amarokdb.* to amarokuser@localhost ;
Query OK, 0 rows affected (0.00 sec)

And that’s it. You can now check that you can connect to the MySQL server using this command:
mysql -u amarokuser -p'amarokpasswd' amarokdb

HOWTO: Create a FTP server with user access (proftpd)

A. The GUI way (for beginners only)

For those who are new to linux and don’t want to use a FTP server without GUI, or just for those who don’t use often their FTP server and wish to set it
quickly without a high level of security, there is a GTK GUI for proftpd.
Be careful, it’s less secure than configuring yourself your server.

1. Install proftpd and gproftpd with synaptic or with this command:
Code:

sudo apt-get install proftpd gproftpd

2. Play with the GUI and set up quickly your server.

Feel free to post here if you have some problems with gproftpd but it shouldn’t be too hard to use (it took me 2 minutes to set up a small FTP server ).

B. The secure way

1. Install proftpd with synaptic or with this command:
Code:

sudo apt-get install proftpd

2. Add this line in /etc/shells file (sudo gedit /etc/shells to open the file):
Code:

/bin/false

Create a /home/ftp directory:
Code:

cd /home
sudo mkdir ftp

Create a user named ftp_user which will be used only for ftp access. This user don’t need a valid shell (more secure) therefore select /bin/false shell
for ftp_user and /home/ftp as home directory (property button in user and group window).
To make this section clearer, i give you the equivalent command line to create the user, but it would be better to use the GUI (System -> Administration -> User -> Group) to create the user since users here often got problems with the user creation and the password (530 error) with the command line, so i really advice to use the GUI :
Code:

sudo useradd ftp_user -p your_password -d /home/ftp -s /bin/false
sudo passwd ftp_user

In ftp directory create a download and an upload directory:
Code:

cd /home/ftp/
sudo mkdir download
sudo mkdir upload

Now we have to set the good permissions for these directories:
Code:

cd /home
sudo chmod 755 ftp
cd ftp
sudo chmod 755 download
sudo chmod 777 upload

3. OK, now go to the proftpd configuration file:
Code:

sudo gedit /etc/proftpd/proftpd.conf

and edit your proftpd.conf file like that if it fit to your need:

Code:

# To really apply changes reload proftpd after modifications.
AllowOverwrite on
AuthAliasOnly on
 
# Choose here the user alias you want !!!!
UserAlias sauron userftp
 
ServerName "Server_Name"
ServerType standalone
DeferWelcome on
 
MultilineRFC2228 on
DefaultServer on
ShowSymlinks off
 
TimeoutNoTransfer 600
TimeoutStalled 100
TimeoutIdle 2200
 
DisplayFirstChdir .message
ListOptions "-l"
 
RequireValidShell off
 
TimeoutLogin 20
 
RootLogin off
 
# It's better for debug to create log files
ExtendedLog /var/log/ftp.log
TransferLog /var/log/xferlog
SystemLog /var/log/syslog.log
 
#DenyFilter \*.*/
 
# I don't choose to use /etc/ftpusers file (set inside the users you want to ban, not useful for me)
UseFtpUsers off
 
# Allow to restart a download
AllowStoreRestart on
 
# Port 21 is the standard FTP port, so you may prefer to use another port for security reasons (choose here the port you want)
Port 1980
 
# To prevent DoS attacks, set the maximum number of child processes
# to 30. If you need to allow more than 30 concurrent connections
# at once, simply increase this value. Note that this ONLY works
# in standalone mode, in inetd mode you should use an inetd server
# that allows you to limit maximum number of processes per service
# (such as xinetd)
MaxInstances 8
 
# Set the user and group that the server normally runs at.
User nobody
Group nogroup
 
# Umask 022 is a good standard umask to prevent new files and dirs
# (second parm) from being group and world writable.
Umask 022 022
 
PersistentPasswd off
 
MaxClients 8
MaxClientsPerHost 8
MaxClientsPerUser 8
MaxHostsPerUser 8
 
# Display a message after a successful login
AccessGrantMsg "welcome !!!"
# This message is displayed for each access good or not
ServerIdent on "you're at home"
 
# Set /home/ftp directory as home directory
DefaultRoot /home/ftp
 
# Lock all the users in home directory, ***** really important *****
DefaultRoot ~
 
MaxLoginAttempts 5
 
#VALID LOGINS
 
AllowUser userftp
DenyALL
</Limit>
 
<Directory /home/ftp>
Umask 022 022
AllowOverwrite off
<Limit MKD STOR DELE XMKD RNRF RNTO RMD XRMD>
DenyAll
</Limit>
</Directory>
 
<Directory /home/ftp/download/*>
 
Umask 022 022
AllowOverwrite off
<Limit MKD STOR DELE XMKD RNEF RNTO RMD XRMD>
DenyAll
</Limit>
</Directory>
 
<Directory> /home/ftp/upload/>
Umask 022 022
AllowOverwrite on
<Limit READ RMD DELE>
 
DenyAll
</Limit>
 
<Limit STOR CWD MKD>
AllowAll
</Limit>
</Directory>

Ok you have done proftpd configuration. Your server is on port 1980 (in this exemple) and the access parameters are
user: ftp_user
password: the one you’ve set for ftp_user

4. To start/stop/restart your server:
Code:

sudo /etc/init.d/proftpd start
sudo /etc/init.d/proftpd stop
sudo /etc/init.d/proftpd restart

To perform a syntax check of your proftpd.conf file:
Code:

sudo proftpd -td5

To know who is connected on your server in realtime use “ftptop” command (use “t” caracter to swich to rate display), you can also use the “ftpwho”
command.

Prevent X.Org from Starting in Ubuntu

Prevent X.Org from Starting in Ubuntu

If you’ve got an Ubuntu machine that you initially installed with Ubuntu Desktop, but would like to run as a server, you can just disable the graphical
environment from starting up in order to save resources. This is also useful for doing system maintenance from the command line that needs to be performed
outside of the GUI.

The only reason to do this instead of removing the packages would be because you might want to still sometimes use the box through the GUI.

Disable X.Org

In order to disable the graphical environment, we’ll need to disable GDM, the Gnome Display Manager. In order to do this, you’ll need to run the following
command at the terminal:

sudo update-rc.d -f gdm remove

When you restart your computer, you’ll be presented with a text-mode login prompt instead of the graphical environment.

Run X.Org While Disabled

If you want to run the graphical environment, all you have to do is type the following command from the prompt, making sure to run it as your normal user
account.

startx

The annoying gray screen will go away once Gnome is fully started.

Enable X.Org

If you want to re-enable X11 it’s a simple matter of running this command from the terminal:

sudo update-rc.d -f gdm defaults

When you restart, you’ll be presented with the graphical prompt again.

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