How to let bash subshell to inherit parent's set options?

Question

Let’s say I do set -x in a script “a.sh”, and it invokes another script “b.sh”.

Is it possible to let “b.sh” inherit the -x option from “a.sh”?

Answer 1

export SHELLOPTS

for example:

echo date > b.sh
chmod +x b.sh

without the export, we only see the commands in ./a.sh when it calls ./b.sh:

$ echo ./b.sh > a.sh
$ bash -xv a.sh

./a.sh
+ ./b.sh
Sun Dec 29 21:34:14 EST 2013

but if we export SHELLOPTS, we see the commands in ./a.sh and ./b.sh

$ echo "export SHELLOPTS; ./b.sh" > a.sh
$ bash -xv a.sh

./a.sh
+ ./b.sh  date
++ date   
Sun Dec 29 21:34:36 EST 2013