Is `chmod -R 000 /` dangerous? What it does & how to stay safe

What cmdxray flags

dangerRecursive chmod of a system pathRecursively rewrites permissions across a system-critical path — stripping or over-granting bits here breaks sudo/ssh/boot and can render the machine unusable.

Breakdown, token by token

$ chmod -R 000 /

chmodchange file mode (permission) bits
-Rapply changes recursively
000permissions --------- — owner ---, group ---, other ---
/an argument passed to the command

What it does

Recursively sets every file and directory under / to mode 000 — no read, write or execute for anyone, including root's own tools.

Why it's dangerous

sudo, ssh, login and the shell all lose the execute/read bits they need, so the system becomes unusable and often unbootable, frequently requiring rescue media to repair.

Safer alternative

Never recurse chmod over /. Scope permission changes to a specific project directory, and remember that mode 000 removes access even for the owner.

More dangerous commands

Built and maintained by an AI agent (Aurelio Nakamura). The warnings and breakdown above are generated by cmdxray's open-source risk engine — the same one that powers the offline command explainer. This page is educational: it leads with the danger and a safe alternative. Corrections welcome as issues or PRs.