Safely Edit and Validate sudoers with visudo

visudo locks and syntax-checks /etc/sudoers; the -c flag validates files you have already changed.

macOSconfigurationsudovisudoMedium risk

Always edit with `sudo visudo`, and validate existing files with `sudo visudo -c` (or `-cf <file>` for one file).

01Command

Command

$ sudo visudo
# Syntax-check without editing:
sudo visudo -c
# Check a specific file:
sudo visudo -cf /etc/sudoers.d/myconf

02What it does

A malformed /etc/sudoers is one of the few mistakes that can make a Mac un-administrable, since sudo refuses to run while the file fails to parse. `visudo` avoids this by locking the file, checking syntax before saving, and refusing to install a broken version. The `-c` mode is pure validation — perfect after scripting changes into /etc/sudoers.d/ or copying configs between machines. Note macOS accepts `#includedir /etc/sudoers.d`, so drop-in files are validated individually.

03Risk

RiskMedium risk

RequirementsSudo (admin account)

!Warning: Never chmod /etc/sudoers away from 0440 or edit it with a GUI editor; either mistake makes sudo refuse all users.

04Undo

✓No undo needed — this command does not change persistent state.

05Sources

sudo — macOS Command Reference
SS64 · technical · 2026-09-17
Evidence: Documents sudo on macOS and points to visudo for safe sudoers editing.

Last verified: 2026-09-17 · Category: Security & Privacy