ref: acde9cddfda6e49d5093c6deee0076c6415d6ded dir: /testdir/t.split9a/
BEGIN { FS = "a" } { n = split ($0, x, FS) if (n != NF) print "botch at ", NR, n, NF for (i=1; i<=n; i++) if ($i != x[i]) print "diff at ", i, x[i], $i }