Is there an easy way to set nullglob for one glob

In bash, if you do this:

mkdir /tmp/empty
array=(/tmp/empty/*)

you find that array now has one element, "/tmp/empty/*", not zero as you'd like. Thankfully, this can be avoided by turning on the nullglob shell option using shopt -s nullglob

But nullglob is global, and when editing an existing shell script, may break things (e.g., did someone check the exit code of ls foo* to check if there are files named starting with "foo"?). So, ideally, I'd like to turn it on only for a small scope—ideally, one filename expansion. You can turn it off again using shopt -u nullglob But of course only if it was disabled before:

old_nullglob=$(shopt -p | grep 'nullglob$')
shopt -s nullglob
array=(/tmp/empty/*)
eval "$old_nullglob"
unset -v old_nullglob

makes me think there must be a better way. The obvious "put it in a subshell" doesn't work as of course the variable assignment dies with the subshell. Other than waiting for the Austin group to import ksh93 syntax, is there?

Solution

With mapfile in Bash 4, you can load an array from a subshell with something like: mapfile array < <(shopt -s nullglob; for f in ./*; do echo "$f"; done). Full example:

$ shopt nullglob
nullglob        off
$ find
.
./bar baz
./qux quux
$ mapfile array < <(shopt -s nullglob; for f in ./*; do echo "$f"; done)
$ shopt nullglob
nullglob        off
$ echo ${#array[@]}
2
$ echo ${array[0]}
bar baz
$ echo ${array[1]}
qux quux
$ rm *
$ mapfile array < <(shopt -s nullglob; for f in ./*; do echo "$f"; done)
$ echo ${#array[@]}
0

Be sure to glob with ./* instead of a bare * when using echo to print the file name
Doesn't work with newline characters in the filename :( as pointed out by derobert

If you need to handle newlines in the filename, you will have to do the much more verbose:

array=()
while read -r -d $'\0'; do
    array+=("$REPLY")
done < <(shopt -s nullglob; for f in ./*; do printf "$f\0"; done)

But by this point, it may be simpler to follow the advice of one of the other answers.