The packages have something known as dependencies. For example , package cowsay
depends on perl
( and you can verify that with apt-cache show pkgname
). When you install a package, apt-get installs additional dependencies as well, but when removing a package - apt-get leaves dependencies alone, and you have to use autoremove option
On the other hand, it also doesn't account for the cache packages, i.e. the actual .deb
package which apt
downloads, then extracts stuff from it and compiles.
Check this:
$ apt-cache show cowsay | grep -i size
Installed-Size: 88
Size: 18532
Alldeb
packages have this Installed-Size
information field which by definition is
estimated installed size in bytes, divided by 1024 and rounded up
( Notice, it's estimated, it's may vary with the actual amount of installed files, and depend on how meticulous the package maintainer is about the details )
So the estimated installation will be 88*1024 = 90112 or 90.1 kB in size. And it coincides with what purge
says:
After this operation, 90.1 kB disk space will be freed.
After I have purged the package, the archive however is still there:
$ ls /var/cache/apt/archives/cowsay_3.03+dfsg1-6_all.deb
/var/cache/apt/archives/cowsay_3.03+dfsg1-6_all.deb
You can use apt-get
flags clean
and autoclean
as well as remove those manually