Seems the usage message for oid2name calls it pg_oid2name. Fixed.

bmomjian · bmomjian · commit 53c1f64b29c4 · 2004-03-03T14:24:12.000Z
diff --git a/contrib/oid2name/oid2name.c b/contrib/oid2name/oid2name.c
@@ -158,7 +158,7 @@ get_opts(int argc, char **argv, struct options * my_opts)
 			case '?':
 			case 'h':
 				fprintf(stderr, "\
-Usage: pg_oid2name [-d database [-x] ] [-t table | -o oid]\n\
+Usage: oid2name [-d database [-x] ] [-t table | -o oid]\n\
         default action        display all databases\n\
         -d database           database to oid2name\n\
         -x                    display system tables\n\
