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.

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 VPS “4gb seg fix up” Problem

It’s a known issues on Xen based Virtual Private Server (VPS) that often it shows “4gb seg fix up” error messages. After a few search I found this command to fix it.

Run the commands below on DomU

First try disabling tls by renaming it to tls.disabled:

mv /lib/tls /lib/tls.disabled

If this doesn’t work then try this command:

echo 'hwcap 0 nosegneg' > /etc/ld.so.conf.d/libc6-xen.conf && ldconfig

after that you’ll need to restart the VPS

Checking Your Linux Centos Version

To check your Linux Centos version, just type:

cat /etc/redhat-release

it will show you the information like this:

CentOS release 5 (Final)

gOS: Good OS for Google Enthusiast

Remember the fuzz about Google launching Google OS (Operating System) spread among Google mania back a few months ago? Well, up until this post is posted, it seems that Google OS is not going to happen. Feel disappointed? Don’t be! As other Google enthusiasts is trying to make it happen!

More »

Creating /dev/random

Somehow in some Linux Centos installation the /dev/random is missing. The problem is some software needs it to working well. Here is how to create it:

mknod /dev/random c 1 9

Other devices might be missing to such as /dev/urandom, /dev/null and /dev/ptmx if you need those device here is how to create it:

mknod /dev/urandom c 1 9

mknod /dev/ptmx c 5 2

mknod /dev/null c 1 3
chmod +666 /dev/null