Add 'G' argument predicate in Eshell

* lisp/eshell/em-pred.el (eshell-predicate-alist): Add 'G' predicate.
(eshell-predicate-help-string): Document it.  (Bug#54470)

* test/lisp/eshell/em-pred-tests.el
(em-pred-test/predicate-effective-gid): New test.

* doc/misc/eshell.text (Argument Predication): Document 'G' predicate.

1 files changed, 5 insertions, 4 deletions

diff --git a/lisp/eshell/em-pred.el b/lisp/eshell/em-pred.el
index 8afc86dd41a..eb5109b82dc 100644
--- a/lisp/eshell/em-pred.el
+++ b/lisp/eshell/em-pred.el
@@ -88,10 +88,10 @@ ordinary strings."
             (if (file-exists-p file)
                 (= (file-attribute-user-id (file-attributes file))
                    (user-uid)))))
-    ;; (?G . (lambda (file)               ; owned by effective gid
-    ;;         (if (file-exists-p file)
-    ;;             (= (file-attribute-user-id (file-attributes file))
-    ;;                (user-uid)))))
+    (?G . (lambda (file)               ; owned by effective gid
+            (if (file-exists-p file)
+                (= (file-attribute-group-id (file-attributes file))
+                   (group-gid)))))
     (?* . (lambda (file)
             (and (file-regular-p file)
                  (not (file-symlink-p file))
@@ -161,6 +161,7 @@ PERMISSION BITS (for owner/group/world):
 
 OWNERSHIP:
   U               owned by effective uid
+  G               owned by effective gid
   u(UID|\\='user\\=')   owned by UID/user
   g(GID|\\='group\\=')  owned by GID/group