src/Doc/System/Phabricator.thy

 
 
 section \<open>Quick start\<close>
 
 text \<open>
-  The starting point is a fresh installation of \<^bold>\<open>Ubuntu 18.04 or 20.04
+  The starting point is a fresh installation of \<^bold>\<open>Ubuntu 20.04
   LTS\<close>\<^footnote>\<open>\<^url>\<open>https://ubuntu.com/download\<close>\<close>: this version is mandatory due to
   subtle dependencies on system packages and configuration that is assumed by
   the Isabelle setup tool.
 
   For production use, a proper \<^emph>\<open>Virtual Server\<close> or \<^emph>\<open>Root Server\<close> product

 
     Then reload (or restart) Apache like this:
     @{verbatim [display] \<open>  systemctl reload apache2\<close>}
 
     \<^item> Install \<^verbatim>\<open>certbot\<close> from \<^url>\<open>https://certbot.eff.org\<close> following the
-    description for Apache and Ubuntu 18.04 or 20.04 on
+    description for Apache and Ubuntu 20.04 on
     \<^url>\<open>https://certbot.eff.org/lets-encrypt/ubuntubionic-apache\<close>. Run
     \<^verbatim>\<open>certbot\<close> interactively and let it operate on the domain
     \<^verbatim>\<open>vcs.example.org\<close>.
 
     \<^item> Inform Phabricator about its new domain name like this:

 
 subsection \<open>\<^verbatim>\<open>isabelle phabricator_setup\<close>\<close>
 
 text \<open>
   The @{tool_def phabricator_setup} tool installs a fresh Phabricator instance
-  on Ubuntu 18.04 or 20.04 LTS:
+  on Ubuntu 20.04 LTS:
   @{verbatim [display] \<open>Usage: isabelle phabricator_setup [OPTIONS]
 
   Options are:
     -M SOURCE    install Mercurial from source: local PATH, or URL, or ":"
     -R DIR       repository directory (default: "/var/www/phabricator-NAME/repo")

   further packages required by Phabricator. This might require a reboot.
 
   Option \<^verbatim>\<open>-M:\<close> installs a standard Mercurial release from source --- the one
   that is used by the Phabricator hosting service
   \<^url>\<open>https://admin.phacility.com\<close>. This avoids various problems with the
-  package provided by Ubuntu 18.04 or 20.04. Alternatively, an explicit file
-  path or URL the source archive (\<^verbatim>\<open>.tar.gz\<close>) may be given here. This option
-  is recommended for production use, but it requires to \<^emph>\<open>uninstall\<close> existing
+  package provided by Ubuntu 20.04. Alternatively, an explicit file path or
+  URL the source archive (\<^verbatim>\<open>.tar.gz\<close>) may be given here. This option is
+  recommended for production use, but it requires to \<^emph>\<open>uninstall\<close> existing
   Mercurial packages provided by the operating system.
 
   Option \<^verbatim>\<open>-n\<close> provides an alternative installation name. The default name
   \<^verbatim>\<open>vcs\<close> means ``version control system''. The name appears in the URL for SSH
   access, and thus has some relevance to end-users. The initial server URL