systemctl: warning about missing install info for template units

The advice string didn't talk about template units at all. Extend
it and print when trying to enable a template unit without install info.

Fixes #2345.

1 files changed, 6 insertions, 3 deletions

diff --git a/src/systemctl/systemctl.c b/src/systemctl/systemctl.c
index cfdc851a6d..115c00ea9c 100644
--- a/src/systemctl/systemctl.c
+++ b/src/systemctl/systemctl.c
@@ -5527,15 +5527,18 @@ static int enable_unit(int argc, char *argv[], void *userdata) {
         }
 
         if (carries_install_info == 0)
-                log_warning("The unit files have no [Install] section. They are not meant to be enabled\n"
-                            "using systemctl.\n"
+                log_warning("The unit files have no installation config (WantedBy, RequiredBy, Also, Alias\n"
+                            "settings in the [Install] section, and DefaultInstance for template units).\n"
+                            "This means they are not meant to be enabled using systemctl.\n"
                             "Possible reasons for having this kind of units are:\n"
                             "1) A unit may be statically enabled by being symlinked from another unit's\n"
                             "   .wants/ or .requires/ directory.\n"
                             "2) A unit's purpose may be to act as a helper for some other unit which has\n"
                             "   a requirement dependency on it.\n"
                             "3) A unit may be started when needed via activation (socket, path, timer,\n"
-                            "   D-Bus, udev, scripted systemctl call, ...).\n");
+                            "   D-Bus, udev, scripted systemctl call, ...).\n"
+                            "4) In case of template units, the unit is meant to be enabled with some\n"
+                            "   instance name specified.");
 
         if (arg_now && n_changes > 0 && STR_IN_SET(argv[0], "enable", "disable", "mask")) {
                 char *new_args[n_changes + 2];