Change -U udsname to -U sockfile for clarification.

quark.1

@@ -12,7 +12,7 @@
 .Op Fl p Ar port
 .Oc
 |
-.Op Fl U Ar udsocket
+.Op Fl U Ar sockfile
 .Oc
 .Op Fl d Ar dir
 .Op Fl l
@@ -49,9 +49,9 @@ for incoming connections.
 Set user ID to the ID of
 .Ar user
 when dropping privileges.
-.It Fl U Ar udsocket
-Create the UNIX-domain socket
-.Ar udsocket
+.It Fl U Ar sockfile
+Create the UNIX-domain socket file
+.Ar sockfile
 and listen on it for incoming connections.
 .It Fl v
 Print version information to stdout and exit.

quark.c

@@ -912,7 +912,7 @@ getusock(char *udsname)
 static void
 usage(void)
 {
-	die("usage: %s [-v] [[[-h host] [-p port]] | [-U udsocket]] "
+	die("usage: %s [-v] [[[-h host] [-p port]] | [-U sockfile]] "
 	    "[-d dir] [-l] [-L] [-u user] [-g group]\n", argv0);
 }