You can find more solution on https://askubuntu.com/questions/1028522/how-can-i-install-pdftk-in-ubuntu-18-04-bionic
User pgoetz's solution is ,in my opinion, the cleanest one: just
sudo snap install pdftk-smoser
and then alias the pdftk-smoser.pdftk command to pdftk.
You can find more solution on https:/ /askubuntu. com/questions/ 1028522/ how-can- i-install- pdftk-in- ubuntu- 18-04-bionic
User pgoetz's solution is ,in my opinion, the cleanest one: just
sudo snap install pdftk-smoser
and then alias the pdftk-smoser.pdftk command to pdftk.