How to create a variable with error going to /dev/null

Question

I am not able to redirect an expected error to &>/dev/null in the following simple code.

xml=`ls ./XML_30fps/*.xml ./XML_24fps/*xml`

The expected error is due to the fact that one of the folders could be empty and so the error would be "No such file or directory." I don't want this error to show up to the users.

I could resolve this by breaking down this line of code but I was wondering if there was a simple way to redirect to null with a single line of code in such case. Neither of these work:

xml=`ls ./XML_30fps/*.xml ./XML_24fps/*xml` &>/dev/null

xml=`ls ./XML_30fps/*.xml ./XML_24fps/*xml &>dev/null`

This link How to avoid printing an error in the console in a BASH script when executing a command? kind of touch upon this but it is not as clear as my question and the answer given here.

Answer 1

How about substituting your command with an alternative that doesn't write to stderr, e.g.

xml=()
if [ -d XML_24fps ]; then
  xml+=($(find XML_24fps -maxdepth 1 -type f -name '*.xml'))
fi
if [ -d XML_30fps ]; then
  xml+=($(find XML_30fps -maxdepth 1 -type f -name '*.xml'))
fi
echo ${xml[@]}

In the above, we're using find to locate all *.xml files in a subfolder. We put a guard condition so that we do not run find on folders that do not exist.

By noting that XML_24fps and XML_30fps are very similar with the difference being just the 24 and 30 we can refactor the above with a {24,30} expansion as follows:

xml=()
for d in XML_{24,30}fps
do
  if [ -d $d ]; then
    xml+=($(find $d -maxdepth 1 -type f -name '*.xml'))
  fi
done
echo ${xml[@]}

Answer 2

Redirect it within the subshell:

xml=`exec 2>/dev/null; ls ./XML_30fps/*.xml ./XML_24fps/*xml`

Or

xml=$(exec 2>/dev/null; ls ./XML_30fps/*.xml ./XML_24fps/*xml)