exit status if the group in question doesn't exist, so we can't use
dseditgroup on Leopard to check whether the access_bpf group exists.
Instead, as per Martin Williams' suggestion in bug 6526, use "dscl .
-read /groups/{group}" instead; the suggestion came from the addgroup.sh
script in
https://developer.apple.com/library/mac/documentation/OpenSource/Conceptual/ShellScripting/ShellScripting.pdf
svn path=/trunk/; revision=41680
BPF_GROUP="access_bpf"
BPF_GROUP_NAME="BPF device access ACL"
-dseditgroup -q -o read "$BPF_GROUP" > /dev/null 2>&1 || \
+dscl . -read /Groups/"$BPF_GROUP" > /dev/null 2>&1 || \
dseditgroup -q -o create "$BPF_GROUP"
dseditgroup -q -o edit -a "$USER" -t user "$BPF_GROUP"