January, 2009

How many Top applications are in Linux?

I don’t know how many Top applications are in Linux. However MARKUS FEILNER AND SASCHA SPREITZER over at Linux Pro Magazine have evaluated all that they could and come up with a top ten for use to use.

As you might expect the original Top came in number one. I was surprised at the number of uses the other Tops came up with.

My favorite is Power Top since all that I use is a notebook. Occasionally it gets hot but the fan doesn’t come on. Maybe Power Top can help me with that!

Another one that I like is MyTop for MySQL. You can use MyTop to analyze what is going on with your MySQL database. There’s alsp PTop for PostGRE users.

Head over to their website and check out the article. You may find a Top that you really like!

-j

VirtualBox releases version 2.1.2 with wireless NIC support

The newest version of VirtualBox has the native ability to use host interface networking and attach to your host’s wireless NIC. This gives users the ability to use a local ip of their network for network access and maintain an internet connection. In other words your virtual machines can now become an integral part of your LAN.

If you’ve ever tried to use wireless with a virtualized machine you know that it is a royal PITA. With this new version of VirtualBox this is no longer the case.

The 2.1.0 version was released in December of 2008. If you tried this version you probably found that you had numerous problems in many areas. Personally it crashed my Centos 5.2 installation. Trying an upgrade failed to clean up files and in general wreaked havoc during the boot phase of the host machine.

This latest version appears to have most of this cleaned up. However, to be safe, if you are using a 2.0 version or lower I would uninstall it rather than upgrade. You should also do a manual search and destroy of any leftover files. You can make quick work of this by issuing the following commands after uninstall:

locate -i vbox | xargs rm -Rf
updatedb
locate -i vbox

You should not get any return after the last command.

All of that said this newest version of VirtualBox looks very promising with it’s ability to natively connect to the host’s wireless NIC and LAN. You can download it here. It is available for Linux, Solaris, Windows and Mac.

-j

Broadcom releases open source wireless drivers

Broadcom has released an open source version of their wireless drivers.

The driver is available for 32 and 64 bit operating systems. It supports 802.11a/b/g/n wireless protocols so it should work for any network. It is designed for use on Broadcom’s BCM4311, 4312, 4321 and 4322 based hardware.

The software comes in tar files for download. This means that you will need your development kernel and kernel headers for your distribution to compile the driver.

The binary driver files are designed to work with any version of the Linux kernel using operating system specific files. That should make it viable for any Linux distribution.

You can download the drivers here.

-j

Open Souce software is literally making money..

Open source software is literally making money in Holland.

Stani Michiels, a Belgian artist and open source software developer, won the competition to design the new 5-Euro commentorative coin. The competition was set up by the Dutch Ministry of Finance.

His winning design was developed entirely with open source software, has now been implemented and is a legal coin in Holland. The theme of the competition was “Holland and Architecture”. Competition was by invitation only to a select group of architectural firms and individuals.

Michiels says in his blog “All the developing and processing was done on GNU/Linux machines which were running Ubuntu/Debian.”

How he went about designing his coin is wildly interesting as is the software and hardware that he used to generate the graphics. You can read all about it on his blog.

-j
architecture

Using the Korn Shell with Linux

My current consulting gig requires that I use the Korn Shell and modify Unix scripts so that they will work with Linux. While the Korn Shell has many comparable characteristics of BASH there are some distinct differences-or at least ones that I’ve never seen in BASH.

The first difference that I noticed is tab completion. For example let’s say that I issue the command

ls /home/jlittle

and hit the tab key to see the files and directories. The output that you see will be in this format

ls /home/jlittle/
1) CentOS-5.2-x86_64-bin-DVD/
2) Desktop/
3) Documents/
4) Video call snapshot 8.png
5) bin/
6) ffmpeg.cfg

At this point you can either choose a number and hit the tab key or type in the first couple of letter of what you want to see or do. The complete output when using the number would look like this

ls /home/jlittle/<tab>
1) CentOS-5.2-x86_64-bin-DVD/
2) Desktop/
3) Documents/
4) Video call snapshot 8.png
5) bin/
6) ffmpeg.cfg
ls /home/jlittle/Desktop/<2tab>
Project-timeSheet.ods Skype.desktop

Typing 2 tab and the tab completion gives us the listing of the /home/jlittle/. Kind of a cool way of doing tab completion don’t you think?

You should also not use the “test” built-in that is available in bash. In bash the test built-in is the same as the “[" built-in. In other words don't use

if test $# -gt 0; then

instead use:

if [ $# -gt 0 ]; then


The korn shell also prefers the use of double brackets syntax “[[ ]]” instead of single brackets. This adds additional operators such as && and ||:

if [[ $# -gt 0 && $? -eq 0 ]]; then


You can use && and || to construct shorthand for an “if” statement in the case where the if statement has a single consequent line:

[ $# -eq 0 ] && exit 0


The Korn Shell is a powerful tool that can make your job easier. Since it’s creation several features have been added while maintaining backwards compatibility with the Bourne shell. The Korn shell can also be used as a programming language which gives it a distinct advantage of typical Unix and Linux shells.

Give ksh a whirl. I haven’t even scratched the surface of what the Korn shell can do for your scripting. If you are used to scripting with Bash then learning the Korn shell should only have a mild learning curve while presenting you with additional scripting power and speed.

-j

Turning tape compression on and off using the Linux mt command

It took quite a bit of google searching to find out how to turn tape compression on and off using the Linux mt command. The mt man page information for doing this is not helpful at all.

To turn compression off use 0 as the switch, to turn it on use 2 as the switch and to find out whether it is on or off use 1 as the switch.

Your commands will look like this

mt -f /dev/st0 datcompress 1 # tell if compression on or off
mt -f /dev/st0 datcompress 0 # turns off compression
mt -f /dev/st0 datcompress 2 #turns on compression


-j

Setting script variables using the if..then statement

Recently I found myself wanting to set some variables in a script that I was writing using the if..then statement. I am using the Korn shell but this is bash compatible.

I wanted to do this as the variable command changed depending on if the script was running on Linux, HP-UX or AIX. This saved a ton of typing the same test over and over throughout the script which is about 600 lines.

The basic form of the script is

if [[ $STRING != string ]]; then
VARIABLE=string1
else
VARIABLE=string2
fi


As you can see the if statement is built around the VARIABLE rather than VARIABLE=if statement. Doing it in that form either won’t return any output or give you output that is not useful.

A real world example

VENDOR=$(uname)
if [ $VENDOR != "Linux" ];then
BACKUPHEADER=log “$(date ‘+%D %T’) Checking header.”
else
BACKUPHEADER=/bin/logger -t “VALIDATE LINUX BACKUP: $(date ‘+%D %T’) Checking header.”
fi
[code]
As you can see from the above the Unix command for sending output to syslog is log and is logger on Linux. Now imagine having to run various tests throughout the script and sending the output to syslog depending on the OS. As I mentioned, it saved quite a bit of typing.