To get state of a flag in set -o..
 

How do we get state of a flag in set -o ... that has no direct alias
set [-+] , e.g.

set -o posix
or
set -o vi
?

not, e.g. set -o errexit , as it can be retrieved by

$ echo $-

then it'll be determined if letter e exists at the output string. Please help sincerely.

In bash you can 'echo $SHELLOPTS' or 'set -o' to see what is currently set (the latter is more portable).