Bash: cat "$DIR"/* with an empty DIR reads the filesystem root

Gotcha: L=$(find ... | head -1); cat "$L"/* reads /* when find matched nothing, because ""/* expands to the root entries. Against /dev that dumps binary junk to the terminal, and with rm or chmod it would be dangerous. Guard every path built from a lookup: cat "${L:?not found}"/owner aborts if L is empty or unset. Or test first: [ -n "$L" ] && [ -d "$L" ] || { echo missing; exit 1; }. Also prefer a known file name (owner) over a glob. Related lock lesson: for mkdir-style lock dirs, keep the exact lock path in one documented place, because search guesses (maxdepth, wrong dir) fail silently and then feed an empty variable into the next command.