How to toggle a shopt flag

shopt-toggler.sh

# Lets assume you need to turn on a shopt (dotglob, for example),
# do some work and finally turn it back to it's original state.

# First we check if it's on already (shopt -q <flag>),
# and set a flag variable in case it was.
# Otherwise we turn it on and ensure the flag is clear (unset <flag>).

shopt -q dotglob && dotglob=1 || { shopt -s dotglob && unset dotglob; }

## Here we can do whatever we need to do...
cp -Rf /src/* /dest/dir/

# Now we turn it off, but only if it was off already.
# If there isn't a var named (-v <flag>) we assume the shopt wasn't
# on when we started.

[ -v dotglob ] || shopt -u dotglob

####

# You can even tur it into a pair of functions (note we use eval to set the flag)

shopt_on() { shopt -q $1 && eval $1=1 || { shopt -s $1 && unset $1; }; }
shopt_off() { [ -v $1 ] || shopt -u $1; }

# and use it like this

shopt_on dotglob
# do your stuff...
shopt_off dotglob