Where to find name of package to use in terminal?

[axylox]

Need to use apt-get purge followed by package name, but inputting just the name (e.g. "Spectral") doesn't work.
Where do I find the "official" name?

[zenzen]

I would first try to press Tab twice and see if you get any auto-completion. Otherwise use apt list as suggested and if you need to narrow things down a bit you can pipe the output to grep and type in something "memorable" that is likely to be part of the package:

# -i flag to ignore case sensitive matches
apt list | grep -i spectral

# Provide only part of the name may give better results
apt list | grep -i spe

# matches results that start with "spe"
apt list | grep -i ^spe

Another option, just search for it in the repositories as if you were to install it again, using apt search <package_name>. For example apt search spectral shows me this entry, is it the one you're looking for:

spectral/focal 0.0~2019.11.12+dfsg-2build1 amd64
  Glossy desktop chat client for the Matrix protocol

Otherwise you can always look it up online and that may give you an idea of what's the package name called. Note that if the package is installed as flatpak or snap it won't appear in this list.

[Frog]

I just had this same problem yesterday .... you can go to your download source or the download folder and see the name attached to the folder or download ......

In my case I wanted to remove Xtreme Download Manager the apt name didn't work but the apt file was listed as xdman .... which worked like a charm .....

[jayesh]

I think dpkg -l | grep -i spectral should also do the same.

[axylox]

Thanks for the detailed reply,

apt list | grep -i spectral

and

apt search <package_name>

seem to work very well.

Now the issue is figuring out how to purge flatpak & snap packages...

[axylox]

The problem with apt list is that its output is so long that it won't even show all of it inside the terminal, let alone be convenient enough for me to look through each one to find my package. But piping the output to grep seems to do it.

[zenzen]

@axylox

Now the issue is figuring out how to purge flatpak & snap packages...

As far as I know removing a flatpak package should already purge entirely since it's a self-contained package format. There may be left overs configuration files in your home directory but apparently that's normal and apt purge doesn't eliminate them either:

Does flatpak uninstall have purge option like apt

[Aravisian]

@zenzen

As far as I know removing a flatpak package should already purge entirely since it's a self-contained package format.

It does not: Flatpak will retain any dependencies that were included for the package. Snap will remove more akin to purge, actually. This is an area where Flatpak has a slight advantage on Snap: Flatpak will share dependencies with other Flatpaks whereas Snap will not share them with other Snaps making Snap more bloated.

I just remove:

sudo apt remove flatpak snapd

to eliminate both.

[zenzen]

So, that means that flatpak packages are not actually self-contained if they share dependencies?

[Aravisian]

We could get into a difference of wording.
Eh... I mean, both qualify as containerized.
Personally, I consider Flatpak as having the advantage in sharing dependencies as this saves disk space and reduces bloat as well as saving bandwidth.

So, if you install a bunch of Flatpak packages, the download size of packages will decrease over time and you will not see redundant dependencies.
With Snap, you will have to download that packages dependencies, each and every time, completely contained in that package.
Both of these packaging techniques disregard if you already have these dependencies installed via APT.

You can also use Flatseal with Flatpak to "pry open the lid" so to speak, allowing Flatpak access to talk with system files or settings if you need.
But it still qualifies as a self-contained item since it does provide its own dependencies within the Flatpak framework and is containerized.
It's a better way of handling... though for me, it still is redundant and unnecessary.

[zenzen]

Ah I see, essentially it keeps track of its own dependency list. I thought it was more like snaps or appimages (I don't even know anymore) where everything was entirely self-contained (in the sense that each package has its own set of dependencies even if that means duplication in the system). Well, that's good to know thanks for the explanation!