chmod 444 (r--r--r--)
What chmod 444 does, who gets which permissions, and when to use it — with the exact commands.
| Read (4) | Write (2) | Execute (1) | |
|---|---|---|---|
| Owner | ✔ read | — | — |
| Group | ✔ read | — | — |
| Others | ✔ read | — | — |
Notes
When you'd use 444: Read-only for absolutely everyone, including the owner. Used to protect files from accidental edits — you must chmod it back before writing.
Unix permissions are octal digits — owner, group, others — where read=4, write=2, execute=1, summed per digit. An optional leading digit holds setuid (4), setgid (2) and the sticky bit (1). On a directory, "execute" means permission to enter it and reach files inside.
Other values: 400 · 500 · 555 · 600 · 640 · 644 · 664 · 666 · 700 · 711 · 750 · 755 · 770 · 775 · 777 · 1777 · 2755 · 4755
Frequently asked questions
What does chmod 444 mean?
chmod 444 sets the permission r--r--r--. The owner can read; Group members can read; Everyone else can read.
What is the symbolic notation for chmod 444?
r--r--r-- — three triplets (owner, group, others) of read/write/execute flags.
How do I apply chmod 444 to a whole directory?
Run chmod -R 444 yourdir to apply it recursively. Be careful: files and directories usually should not share the same mode (directories need execute to be entered, regular files usually should not be executable).