How do I create linux system that will not save changes

If you want CentOS 8 (I didn't find the liveCD nor a way to test it without installing like other distributions), take the last version - ending by dvd1.iso not boot.iso), you can install it in VirtualBox (or Qemu). Install, make updates and Take a snapshot. For now on, only quit and restore the previous state. You can install software but your session will be lost if you quit VirtualBox without saving. You can keep your VirtualBox machine up to date by saving the state.

In VirtualBox you have to install the Guest Additions to have Shared folders, Shared clipboard, full screen mode (I had the following error : Kernel headers not found for target kernel, the full screen doesn't work for me now on this OS, maybe you will have more luck or the patience to find the solution) and other functionalities.

If you want to test different distributions, you can either :

• Create a bootable USB from an ISO (in general you can try normal ISO).
• Use Ventoy if you want multiple ISO. For example, KDE and GNOME version or multiple operating systems. (you can use a external drive ; Warning : it will format the destination drive). You just have to install Ventoy and copy ISO on the key or drive.
  • You can use the command line or a GUI (for example in Linux) to
    install Ventoy.
• Use VirtualBox or Qemu.

If you really want the liveCD of CentOS :

Go to this site (bay.uchicago.edu) and download either ISO or torrent.

Note : The End of Lifetime (EOL) dates for CentOS (Maintenance Updates) Your ISO won't be up to date unless you install it on a VirtualBox, make updates and take a snapshot.

• CentOS 7 : 2024-06-30
• CentOS 8 : 2021-12-31

Choose one of the following :

• CentOS-7-x86_64-LiveGNOME-2003.iso
• CentOS-7-x86_64-LiveGNOME-2003.torrent
• CentOS-7-x86_64-LiveKDE-2003.iso
• CentOS-7-x86_64-LiveKDE-2003.torrent

Or here (only ISO not torrents).