[bug#45004] [PATCH shepherd] herd: Suggest alternatives when action and service are likely swapped.

[Leo Prikler]

* modules/shepherd/script/herd.scm (run-command)[reply error]: Report a more
descriptive error if service could reasonably have been an action.
---
 modules/shepherd/scripts/herd.scm | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/modules/shepherd/scripts/herd.scm 
b/modules/shepherd/scripts/herd.scm
index 106de1e..a178f51 100644
--- a/modules/shepherd/scripts/herd.scm
+++ b/modules/shepherd/scripts/herd.scm
@@ -179,6 +179,15 @@ the daemon via SOCKET-FILE."
                 ('messages messages))
         (for-each display-line messages)
         (report-command-error error)
+        (match (list action service)
+          ((_ (or 'start 'stop 'status 'doc))
+           (report-error (l10n "did you mean 'herd ~a ~a'?")
+                         service action))
+          ((root (or 'help 'halt 'power-off 'load 'eval 'unload 'reload
+                     'daemonize 'persistency 'no-persistency 'cd 'restart))
+           (report-error (l10n "did you mean 'herd ~a ~a'?")
+                         service action))
+          ((_ _) *unspecified*))
         (exit 1))
        ((? eof-object?)
         ;; When stopping shepherd, we may get an EOF in lieu of a real reply,
-- 
2.29.2