After updating your centos, you might see the old kernel in the grub menu. This is how you remove the old kernel on centos (if you want to) :

  1. to ensure you really have old kernel installed, use rpm -q kernel to see it.
  2. Install yum-utils with yum install yum-utils
  3. remove it using package-cleanup --oldkernels --count=2. the --count option means how many kernels you want left

To make it always limited amount of kernels left after update, edit /etc/yum.conf and set installonly_limit. If you want always left 2 kernels then use installonly_limit=2

Ever trying to remove a lot of file like this ?

[[email protected]]# ls -l log/ | wc -l
2041335

It wont work if you just remove it with rm because there will be an error message (i.e. /bin/rm: Argument list too long). So how to remove it ?? I use this command to remove it

[[email protected]]# find ./ -name ‘msg.*’ | xargs rm -fv

I’m using msg.* becasue the filenames I want to remove begin with msg.. You can vary it depend on your need.

source of inspiration

Today my fight with sudo is over, I finally can conquer it. Once this error come to me when I using sudo on centos :

Fatal error (bad version): sudo: symbol lookup error: sudo: undefined symbol: audit_log_user_command

After quite long searching for the solution finally got it today. It turns out a simple solution, In my case after I upgrade the audit and it libs sudo works fine. So my mistakes is I’m using the newest sudo but I didn’t upgrade the audit-libs.

Ha, a simple solution but makes me very confused :D