Index: bin/ps/ps.1
===================================================================
--- bin/ps/ps.1
+++ bin/ps/ps.1
@@ -29,7 +29,7 @@
 .\"     @(#)ps.1	8.3 (Berkeley) 4/18/94
 .\" $FreeBSD$
 .\"
-.Dd June 27, 2020
+.Dd November 12, 2020
 .Dt PS 1
 .Os
 .Sh NAME
@@ -175,7 +175,10 @@
 Use
 .Fl J
 .Sy 0
-to display only host processes.
+to display only host processes or
+.Fl J
+.Sy -1
+to display all jailed processes.
 This flag implies
 .Fl x
 by default.
Index: bin/ps/ps.c
===================================================================
--- bin/ps/ps.c
+++ bin/ps/ps.c
@@ -580,7 +580,8 @@
 			}
 			if (jidlist.count > 0) {
 				for (elem = 0; elem < jidlist.count; elem++)
-					if (kp->ki_jid == jidlist.l.jids[elem])
+					if (kp->ki_jid == jidlist.l.jids[elem] ||
+					    (jidlist.l.jids[elem] == -1 && kp->ki_jid != 0))
 						goto keepit;
 			}
 			if (pgrplist.count > 0) {
@@ -796,7 +797,7 @@
 	}
 
 	tempid = jail_getid(elem);
-	if (tempid < 0) {
+	if (tempid < 0 && tempid != strtol(elem, NULL, 10)) {
 		warnx("Invalid %s: %s", inf->lname, elem);
 		optfatal = 1;
 		return (0);