The Apache web server was recently installed on a Debian/Ubuntu server. The web server fails and a review of log messages on another partition reveals the installation was not completed properly due…

apt-get install apache2 performs a fresh installation once the broken package state has been cleared by the purge, completing the setup correctly with the now-available disk space.

apt-get --purge remove apache2 removes the incomplete package along with all associated configuration files, fully clearing the broken installation state so that a subsequent clean install can succeed.

apt-get --reinstall install apache2 reinstalls package files over the existing installation but does not purge configuration files or fully resolve broken package state left by the failed original install.

apt-get --reinstall apache2 is invalid syntax because the --reinstall modifier must be combined with the install subcommand, making this command unrecognized by apt-get.