Archive for the ‘Basics’ Category
Enable USB Support In Virtualbox (Ubuntu)
Enabling USB Support in Virtualbox means to be able to access USB drives plugged into your physical machine on your virtual machines. To accomplish this, you first need to download the newest version of Virtualbox (4.1.8 at the time of this writing), which is not available in the Ubuntu repositories but on the Virtualbox homepage:
https://www.virtualbox.org/wiki/Downloads
Uninstall any previously installed version if present and then install the downloaded Debian package with a package installer taking care of dependencies, such as gdebi.
Next, head back to the homepage and install the Virtualbox Extension pack which supports USB 2.0.
Now you have to make yourself member of the vboxusers group. Go to the Users and Groups Settings in your Control Panel and hit Manage Groups. Scroll down to the vboxusers group and hit Properties. Check the box next to your username and click OK.
Last but not least you have to enable USB for the virtual machine. Close it if it is running and enter the Settings window. On the left panel, select USB. Check Enable USB Controller as well as Enable USB 2.0 (EHCI) Controller. Then click the button with the small green plus-symbol and add the USB device you need:
If you run the machine a USB symbol will indicate that USB is enabled and a device is running on virtual machine:
Guake – Dropdown-Terminal for Gnome
Guake saves you the time of managing your terminal windows with circumstantial key-combinations and mouse-clicks by providing a configurable dropdown-terminal which you can call with F12 by default. Just like with usual terminals, it is possible to create new tabs, but also to edit the opacity, the size, colors and everything you need:
Guake is available in the default Ubuntu, Debian, Fedora and Arch repositories. The source-code is downloadable at http://guake.org/downloads
Kill Processes On Ubuntu
When it comes to killing a frozen process, Ubuntu and its derivatives offer a great variety of ways to do so:
You can open the System Monitor to end or kill a running process. Just right-click and annihilate:
Then there is the Force Quit applet. Not that powerful, but does its job in most of the cases:
Working similarly but more powerful is the xkill command line tool. You can also wrap that one into a launcher and use it the same way as an applet.
Another command line tool is killall followed by the name of the process, granting the advantage of not having to know the process ID of the program, which the next tool requires:
kill, provided with the -9 switch and the ID of the process (available with top or ps) shuts down nearly every running process.
If none of those commands help, there is still the option to close the current session with ctrl + alt + backspace. This however comes with the warranty of losing any data you could not save before!
Install .deb Packages Manually (Linux Debian/Ubuntu)
When you download packages for Linux Debian or Ubuntu they usually come in the .deb format and are installed automatically by your local package manager. If you download them from the internet instead of the repositorial way however you are given the .deb file and have to deal with it yourself. To install it, open a terminal, direct it to the folder where it has been downloaded to with cd and use the dpkg command:
cd /home/ctest/Downloads/
dpkg -i random_name.deb
How to get detailed information about the harddisk installed on a Linux server
Detailed information about the hard disk type, disk vendor etc. of the disk used on a Linux system can be aquired with the linux tool hdparm. If hdparm is not installed on your server, it can be installed with this command (on Debian and Ubuntu systems):
apt-get install hdparm
For other Linux distributions, use the software installer and search for the package name ‘hdparm’.
To get the detailed disk info, run this command
hdparm -I /dev/sda
The device /dev/sda is the first SATA disk on the server, the second disk is /dev/sdb. Replace /dev/sda in the command with the name of the device that you want to query.
Get the disk health status with SMART monitor tools on Debian and Ubuntu Linux
Every modern disk has a internal monitoring function called SMART that keeps track on errors in that disk. There is a software package called smartmontools on Linux which can be used to query the SMART status of the disk to monitor if the disk might fail in near future.
Installation
apt-get install smartmontools
Usage
First we need to know the internal device name of the harddisks. For the first SATA disk, this is normally /dev/sda, the second is /dev/sdb etc. If you are unsure about the device names of your computer, then you can get them with:
fdisk -l
The command lists the partitions e.g. /dev/sda1. To get the device name, use the partition name without the number, e.g. the device of partition/dev/sda1 is /dev/sda.
To get a summary of the healt status of the disk, run:
smartctl –health /dev/sda
replace /dev/sda with the device name of the harddisk that you want to query.
The output will look similar to this:
~# smartctl --health /dev/sda smartctl version 5.38 [x86_64-unknown-linux-gnu] Copyright (C) 2002-8 Bruce Allen Home page is http://smartmontools.sourceforge.net/ === START OF READ SMART DATA SECTION === SMART overall-health self-assessment test result: PASSED
To get the full detailed output of all parameters, use this command:
smartctl –all /dev/sda
Send all outgoing email trough one IP address in postfix
When a server has more then one IP address, then postfix will use all IP addresses randomly to send out emails. This can cause your emails to be listed as SPAM on other servers because the sending IP does not match the reverse IP of the server hostname. The solution is to bind postfix to the primary IP address of the server.
Edit the postfix main.cf file:
vi /etc/postfix/main.cf
and add the line:
smtp_bind_address = 192.168.0.1
were 192.168.0.1 has to be replaced with the primary IP address of the server. Then restart postfix:
/etc/init.d/postfix restart
Install GNOME Desktop On Ubuntu 11.10
If you would like your Ubuntu 11.10 better with the old GNOME desktop (no launcher but a good old system panel and so on), you can just install the gnome package and choose it as your default desktop environment. Therefore open a terminal and enter:
sudo apt-get install gnome
During the installation there will be some prompts that you will have to answer. Click OK on the first one after you are done reading:
Next, you will have to decide which desktop environment you want to configure as your default:
After installation, the GNOME as well as the Unity desktops will be available on the cogwheel-button in the login-screen:
Get the name of the newest file in a directory on the linux shell
If you have a directory with many files (a few thousand in my case) and need to know which one is the newest, then the following command might be useful. It returns the name and details of the newest file in a directory where it is executed:
ls -tl | sed -n 2p
How to Install New Icons and Cursors (Linux Mint)
The way to add new icons and cursors is simple yet not really obvious in Linux Mint. To add new cursors, download any from a webside that provides these (as this), and drag and drop the package file onto the theme preferences of your Control Center:
To add new icons, just download and extract them into /usr/share/icons as root. Afterwards they are available in the Appearance section of the Control Center.