You just need to do
apt-get install --only-upgrade <packagename>. This will upgrade only that single package, and only if it is installed.
If you wish to install the package if it doesn’t exist, or upgrade it if it does, you may leave out
In order to update a single package using the CLI:
sudo apt-get install --only-upgrade <packagename>
sudo apt-get install --only-upgrade ack
Reading package lists... Done Building dependency tree Reading state information... Done Skipping **ack**, it is not installed and only upgrades are requested. 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
There are two possible ways I can think of:
sudo apt-get install nameofpackage
This will upgrade the package even if is already installed:
~$ sudo apt-get install emesene Reading package lists... Done Building dependency tree Reading state information... Done The following packages will be upgraded: emesene 1 upgraded, 0 newly installed, 0 to remove and 5 not upgraded. Need to get 1,486 kB of archives. After this operation, 696 kB disk space will be freed. Get:1 http://il.archive.ubuntu.com/ubuntu/ natty-updates/universe emesene all 2.11.4+dfsg-0ubuntu1 [1,486 kB]
Synaptic Package Manager: Right click→Mark for upgrade:
Note: Sometimes it may asks for additional packages or dependencies, it is normal.