Linux

How to upgrade a single package using apt-get? 

apt-get install --only-upgrade <packagename>

How to prevent updating of a specific package?

Hold a package:

sudo apt-mark hold <package-name>

Remove the hold:

sudo apt-mark unhold <package-name>

Show all packages on hold:

sudo apt-mark showhold

### To downgrade you have to do a command like

sudo apt-get install pkg_name=version

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How do I check if a package is installed on my server?

Apt list - list of all installed packages

apt list <package> -specific package

If installed it'll print something like (with [installed] at the end of the line):

$ apt -qq list awscli awscli/stable,now 1.4.2-1 all [installed]

If not installed the output will be:

$ apt -qq list awscli awscli/stable 1.4.2-1 all

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