Acquiring 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 its set [-+] e can be retrieved by

$ echo $-

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

You can use set -o without an argument:

$ set -o
allexport       off
braceexpand     on
emacs           off
errexit         off
errtrace        off
functrace       off
hashall         on
histexpand      on
history         on
ignoreeof       off
interactive-comments    on
keyword         off
monitor         on
noclobber       off
noexec          off
noglob          off
nolog           off
notify          off
nounset         off
onecmd          off
physical        off
pipefail        off
posix           off
privileged      off
verbose         off
vi              on
xtrace          off

or look at the SHELLOPTS variable:

$ echo "$SHELLOPTS"
braceexpand:hashall:histexpand:history:interactive-comments:monitor:vi

With bash:

if shopt -qpo posix; then
  echo "turned on";
else
  echo "turned off";
fi

See: help set and help shopt

Source: https://unix.stackexchange.com/a/269776/74329