Sometimes you make some changes to your system and you just know that something will break if a certain package gets updated. You want to keep that certain package from updating until you're ready for it.
In Ubuntu, or any
apt/dpkg based system, you can tell
apt to just hold the current package version using
apt-mark hold. For example, let's say that if the
xxd package gets updated, it will break something for some reason. Tell
apt not to update it.
$ sudo apt-mark hold xxd
When you're ready to start updating it again, tell
apt that it can update it:
$ sudo apt-mark unhold xxd
It's that simple. If you ever want to check what packages are currently in
hold status, there are two ways to do it.
$ dpkg --get-selections | grep "hold" xxd hold
$ apt-mark showhold xxd