tkowal I am a newcomer to DokuWiki and I want to test it on my own machine before trying it on a server. The Ubuntu specific installation page mentions several versions but not 20.04. I stated following instructions on https://www.dokuwiki.org/install:ubuntu. When I issue "apt-get install php7.0-xml" I get "E: Unable to locate package php7.0-xml". Any suggestions on how to proceed?
andi tkowal apt-get install php7.0-xml modern Ubuntu probably has more uptodate PHP releases. So it might be php7.2-xml or php7.3-xml. Use apt search to find the proper packages.
turnermm Ubunutu/Debian package mangers are ususally behind. Moreover, they create a file system structure that is not the easiest to work with. You should consider using the dokuwiki downloader: https://www.dokuwiki.org/install:downloader