Tag Archives: linux

Recursive chmod for files or directories only

To do a recursive chmod to directories only you can run:

And for files only:

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:

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). Continue reading Meaning of /dev/null 2>&1 in Crontab’s Cron Job

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:

If this doesn’t work then try this command:

after that you’ll need to restart the VPS

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:

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: