I quite often need to remove a single line from a file by its line number. The most common use case for me is the known_hosts file when I have reinstalled a system, I have in the past used vim and navigated to the line then removed it. This is all well and good but it gets to be a pain having to do it repeatedly, especially when you manage around 1000 servers and they get rebuilt frequently. Finally today I had had enough so wrote a little script to do this task easily. Hopefully someone else finds this useful

This post is here mainly because I always forget how to do it. This is one of the simplest ways to reinstall a Centos (will probably work for RHEL and maybe even Fedora) system without needing PXE or physical access to the machine. Make sure that you have tested your kickstart before you use it and don’t blame me if anything goes wrong. Save the following script and make it executable then run it. It will ask some questions about networking and hostname and then write a new grub stanza to your grub.conf. It will also download the correct kernel and initrd from the information you have given it and put them in the correct position for grub to find them when it boots.