[Feature] FS can match the empty string [POSIX awk] unknown? [GNU awk 3.1.6] no [Busybox awk 1.11.3] yes [mawk 1.3.3] no [nawk (solaris 2.8)] no no [tawk x.xx] unknown no [NetBSD? awk 20030729] no [jawk 1.02] 
yes