CentOS 6 Setup
CentOS 6 is in archived state, but may still be used for education purposes.
This post guides you through the installation process: (1) Download ISO file (2) Enable Network (3) Set up package manager mirror URL.
Download ISO File
Visit CentOS Vault Mirror and download CentOS-6.10-x86_64-minimal.iso.
Set up a virtual machine with VirtualBox. Make sure to choose a larger dynamic disk size (such as 100 GB). If your disk size is too small, you may need to change it afterwards, and the process is non-trivial.
Enable Network
ping google.com
should report an error: ping: unknown host google.com
ip a
should show something like eth0 in the output.
vi /etc/sysconfig/network-scripts/ifcfg-eth0
and change ONBOOT=no to ONBOOT=yes, and use reboot to reboot.
Set up package manager mirror URL
vi /etc/yum.repos.d/CentOS-Base.repo
and modify with vi commands:
:%s/mirrorlist=http/#mirrorlist=http/g
:%s/#baseurl=http/baseurl=http/g
:%s/mirror\.centos/vault.centos/g
These commands comment out mirrorlist lines and uncomment baseurl lines and replace http://mirror.centos.org/centos/$releasever/[SECTION]/$basearch/ to http://vault.centos.org/centos/$releasever/[SECTION]/$basearch/.
perform the modifcations on all 5 sections: [base], [updates], [extras], [centosplus], [contrib].
yum update
Install tmux
See this post to install from source. I have trouble installing it through yum.
VirtualBox Guest Additions
If the OS is installed in VirtualBox, you can insert Guest Additions CDROM and install with:
sudo mkdir -p /mnt/cdrom
sudo mount -t auto /dev/cdrom1 /mnt/cdrom
cd /mnt/cdrom
sudo sh ./VBoxLinuxAdditions.run --nox11
lsmod | grep vboxguest
See this post for more details.