$ set PERLDB_OPTS="ReadLine 0"

$ perl -de 42
Invalid option `"ReadLine 0"'

$ set PERLDB_OPTS=ReadLine 0

$ perl -de 42
Option `ReadLine' is non-boolean.  Use `o ReadLine=VAL' to set, `o ReadLine?' to query
Unknown option `0'

$ set PERLDB_OPTS=o ReadLine=0

$ perl -de 42
Option `o' is non-boolean.  Use `o ornaments=VAL' to set, `o ornaments?' to query