gnome-core is a meta package and the case will meta package is --
They pull packages to get installed but removing them will not remove all the pulled packages.
So, Unless, you have copied the names of packages installed by gnome-core, It is virtually impossible to remove all the 600 MBs.
But, You can get the names of pulled packages by this command
apt-cache depends gnome-core
And try to remove packages one by one. You should check always, whether it is removing any necessary packages.
Or you can get the list of packages in more useful way by this:
apt-cache depends gnome-core | cut -f 2 -d ':' | tr '\n' ' '
This will list all the dependency of gnome-core package, ignore the package name in <> marks only.
How do I know, whether any system package is being removed?
When you see a lots of space is being freed from the command, (more that 600MB) you should know that, you are removing more than you installed.
apt-get will let you know how much space is going to be freed, before removing like with a message like this
After this operation, 384 kB disk space will be freed.
And When you try to remove essential system package,
apt-get will show you a warning message.
Recommendation: I suggest you to get list of packages from the first command, and try to remove them one by one. It is safer. If you see warning, skip removing that package. I see, Most of the packages in gnome-core is related with gui, I guess removing those packages will not harm your system (If you don't want a gui).
Hope this helps!
Some note on removing packages
How pulled packages get uninstalled when you remove the master package ?
When you install a package, If that package depends on some other packages, The dependency packages also get installed and Marked as auto. That means, the Apt system mark them as Automatically installed as dependency of another package. It helps Apt system to recognize unnecessary packages.
When, you un-install the master package, the pulled packages also marked as obsolete or unnecessary packages in the system. You can remove them by providing
autoremove option to
apt-get. (aptitude automatically remove them with the master package).
An exception to this rule is, if you later install another package which also depends on the pulled packages, the pulled packages will not be marked as obsolete when you remove the first master package.
Example: You installed a package
X that depends on package
Y. When you installed
Y also gets installed and marked as auto. If you do not install another package
Z which also depends on
X will render
Y's usefulness and Apt system will mark it obsolete and you can remove it with
But If you install a package
X which also depends on
Y, then removing only
X does not mark
Y as obsolete package and you can't remove it with
But Note that, If you remove package
Y after installing
X, it will remove package
X can't stay without
Y and you wanted you remove
Y, that means you also wanted to remove
X. apt will remove
X automatically when removing
Y unlike marking it obsolete to later removal by
Try out examples:
ubuntu-desktop package is a meta package. It was used to install standard Ubuntu desktop. Try removing it, only that package will be removed.
Also try installing
lubuntu-desktop package (You may not want to install this, because it is a big download). But, when you try to remove it, only the tiny package
lubuntu-desktop will get removed.
Apt handles meta packages differently
The meta packages like gnome-core, ubuntu-restricted-extras are also called virtual packages. They are called so, because they are basically empty packages, They pull other packages by depending on them. For example, ubuntu-restricted-extras depends on (in 12.04) following packages:
Where, ubuntu-restricted-addons itself is another meta package. Since, meta packages are used for only pulling packages, installing them does not mark the pulled packages as auto, they are marked as manually installed. The result? removing only the master meta package will not mark the pulled packages obsolete and you can't remove them by
autoremove option. That is why, You need to remove each pulled packages of the meta packages manually.
Example: You installed a meta package
X that depends on packages
Z. When you installed it, the
Z packages aren't marked as auto (automatically installed as dependency of another package), instead they marked as manually installed. In later time when you want to remove
X, only the virtual
X package gets removed.Both
Z remain in the system and You can't un-install them with