However some might prefer a GTK approach and/or use a standard installation instead of one relying on OpenJDK. Those more acquainted with the terminal can download and install from there.
You'll need:
gdebi (highly recommended over GNOME Software/Software Center), install it from the software center or $ sudo apt install gdebi
a few dependencies from the artful repositories (.deb files):
Basically the process is opening and installing the .deb files - preferably on gdebi - in the order below. It might be interesting to open pdftk first on gdebi just to see the "impossible dependency" warning. We're basically installing the dependencies from an older repository, so it'll run like it did in 17.10. The order is:
libgcj-common
libgcj17
pdftk
After that you might want to check the status of pdftk at the software center - it might say it is not installed; install there or maybe just let it be.
pdftk is missing from the official repository right now. That's an issue for many people.
There's a workaround here: How can I install pdftk in Ubuntu 18.04 Bionic?
However some might prefer a GTK approach and/or use a standard installation instead of one relying on OpenJDK. Those more acquainted with the terminal can download and install from there.
You'll need:
gdebi (highly recommended over GNOME Software/Software Center), install it from the software center or
$ sudo apt install gdebi
a few dependencies from the artful repositories (.deb files):
pdftk, also from artful repo (download: https://packages.ubuntu.com/artful/pdftk)
Basically the process is opening and installing the .deb files - preferably on
gdebi
- in the order below. It might be interesting to openpdftk
first ongdebi
just to see the "impossible dependency" warning. We're basically installing the dependencies from an older repository, so it'll run like it did in 17.10. The order is:After that you might want to check the status of pdftk at the software center - it might say it is not installed; install there or maybe just let it be.
Go to the terminal and check pdftk:
$ pdftk
It should now be installed.
Not exactly the same thing, but for some operations I've found useful QPDF to manipulate PDFs in Ubuntu 18.04 LTS Bionic Beaver.
At time of this writing (May 2018) the project seems to be active and well mantained.