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 xxdWhen you're ready to start updating it again, tell apt that it can update it:
$ sudo apt-mark unhold xxdIt'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