Manual page install function

Function to install man page.
Verifies that man pages are installed, and correct directory for the pihole manpage is present.
Copies file, and runs man-db to update man page database.

Signed-off-by: Rob Gill <rrobgill@protonmail.com>

automated install/basic-install.sh

@@ -1193,6 +1193,37 @@ installConfigs() {
   fi
 }
 
+install_manpage() {
+  # Copy Pi-hole man page and call mandb to update man page database
+  # Default location for man files for /usr/local/bin is /usr/local/share/man
+  # on lightweight systems may not be present, so check before copying.
+  echo -en "  ${INFO} Testing man page installation"
+  if ! command -v mandb; then
+    # if mandb is not present, no manpage support
+    echo -e "${OVER}  ${INFO} man not installed"
+    return
+  elif [[ ! -d "/usr/local/share/man" ]]; then
+    # appropriate directory for Pi-hole's man page is not present
+    echo -e "${OVER}  ${INFO} man page not installed"
+    return
+  elif [[ ! -d "/usr/local/share/man/man8"]]; then
+    # if not present, create man8 directory
+    mkdir /usr/local/share/man/man8
+  fi
+  # Testing complete, copy the file & update the man db
+  cp ${PI_HOLE_LOCAL_REPO}/pihole.8 /usr/local/share/man/man8/pihole.8
+  if mandb -q &>/dev/null; then
+    # Updated successfully
+    echo -e "${OVER}  ${TICK} man page installed and database updated"
+    return
+  else
+    # Something is wrong with the system's man installation, clean up 
+    # our file, (leave everything how we found it).
+    rm /usr/local/share/man/man8/pihole.8
+    echo -e "${OVER}  ${INFO} man page db not updated, man page not installed"
+  fi
+}
+
 stop_service() {
   # Stop service passed in as argument.
   # Can softfail, as process may not be installed when this is called
@@ -1695,6 +1726,9 @@ installPihole() {
     configureFirewall
   fi
 
+  # install a man page entry for pihole
+  install_manpage
+
   # Update setupvars.conf with any variables that may or may not have been changed during the install
   finalExports
 }