Markus Blog

Delete Files Older Than n Days

In Linux system you can delete old unused files (usually the session files in /tmp) all at once by running this command:

find /path/to/files* -mtime +5 -exec rm {} \;

this command will delete files which is 5 days old, if you want to change the number of days to 3 days old, then you have to change +5 to +3 and run the command again.

Online FLV to MP3 Converter

Do you like to watch video clips of you favorite musician at YouTube.com? As you know, you can download the videos at youtube by using additional plugin for you browser. But the downloaded file will be a .flv file which is a flash video. If you only want to have the music file, you can convert the .flv file into .mp3 file by using a converter available online. More »

error: kernel image does not exist: /boot/hypervm-xen-vmlinuz

If you have a CentOS Xen Dom0 and experiencing this problem “error: kernel image does not exist: /boot/hypervm-xen-vmlinuz” after upgrading Xen kernel on HyperVM based VPS, here is how to fix it: More »

Changing Windows Server 2003 Administrator Password

It’s very easy to change Windows Server 2003 Administrator password if you have physical access to the server, you’ll need to press ctrl + alt + del and you’ll get some option buttons such as Lock Computer, Log Off, Shut Down, etc. on that window, click on Change Password to change your Administrator password (user that currently logged in, so you must log in as Administrator before you can change its password). More »

Firefox 3 Auto Complete URL Bar

I just noticed yesterday that Firefox will do auto complete of URL you type if you already visited that URL before. For example you open http://markus.revti.com yesterday and the URL is stored on Firefox’s history. The next time you want to visit the same URL, you only need to type ‘markus’ and Firefox will show list of URL which have the word ‘markus’ in it. Press ‘TAB’ button and Firefox will do auto complete of URL which is on the first of the list.

Xen VPS modprobe: QM_MODULES: Function not implemented

I got this problem on one of Debian VPS when tried to run iptables command

modprobe: QM_MODULES: Function not implemented
 
modprobe: QM_MODULES: Function not implemented
 
modprobe: Can't locate module ip_tables
iptables v1.3.6: can't initialize iptables table `filter': iptables
who? (do you need to insmod?)
Perhaps iptables or your kernel needs to be upgraded.

To fix this you’ll need to run these commands:
More »

Meaning of /dev/null 2>&1 in Crontab’s Cron Job

If you use cron job on Linux, some times you want to ignore the output of the command you executed. This can be done by adding “> /dev/null 2>&1” behind the cron job command.

The command is just work want it should be, but I always curious with what does 2>&1 means. The “> /dev/null” is pretty obvious of what it does without much more explanation, it just redirect all the output to /dev/null which in Linux means we don’t care with the output (or sort of, it’s my own definition). More »

Xen Debian VPS Problem With nash-hotplug Using 100% CPU Resource

Recently I setup a Debian 4.0 VPS using xen image from jailtime.org, once the VM running I noticed that the load goes 1.0 all the time which make the VM very slow. From top command you’ll see the nash-hotplug process is the cause.

First you can kill it by execute the ‘kill -9 <process id>’ command (without the quotes), where <process id> is the process id of nash-hotplug. Then to automate killing the nash process every time you reboot the VPS run these commands: More »