Software status command

You can use 'apt search' in a terminal or, if you prefer graphical interface, the quick filter in the "Synaptic Packager Manager", which is installed by default.

There is no "java" package. I imagine you want the Java Runtime Environment. If so, install the "default-jre" package.

Thanks magic Banana, you've been a great help all over this forum.

jais@asus-trisquel:~$ apt search default-jre
Sorting... Done
Full Text Search... Done
default-jre/flidas 2:1.8-56ubuntu2 amd64
Standard Java or Java compatible Runtime

default-jre-headless/flidas 2:1.8-56ubuntu2 amd64
Standard Java or Java compatible Runtime (headless)

I ran this, with these results. Do these results mean it is installed, or it is just available for installation?

And hopefully you can enlighten me on a point that I keep coming across. When people say install, what does this nomenclature signify? is the standard command for this "sudo apt install", and do I have to run installations as sudo?

To see a list of all installed packages, use the command:

dpkg --get-selections

You will get a list of packages. Packages with "install" (or whatever it is in your language) are fully installed on your system. There may also be other packages that you removed, but those will be marked with "deinstall".

To search for java you can try to filter the output with "grep" to look for packages with names containing the strings "jre" (java runtime environment) or possibly "jdk" (java development kit):

dpkg --get-selections | grep -e jdk -e jre

For example, "dpkg --get-selections | grep zip" will show all packages on your system with names containing "zip".

You could also search for these names in the synaptic package manager to see if they are installed, if you prefer graphical applications.