chmod 066 Permission Explained
Summary: chmod 066 gives the owner no access, the group read/write, and everyone else read/write.
| Class | Read (4) | Write (2) | Execute (1) | Octal |
|---|---|---|---|---|
| Owner (u) | 0 | |||
| Group (g) | 6 | |||
| Others (o) | 6 |
chmod 066 filename
chmod 066 Breakdown
| Class | Digit | Symbolic | On a file | On a directory |
|---|---|---|---|---|
| Owner (u) | 0 |
--- |
No access | Cannot list, enter, or modify |
| Group (g) | 6 |
rw- |
Read and write | Can list names, cannot enter |
| Others (o) | 6 |
rw- |
Read and write | Can list names, cannot enter |
Is chmod 066 Safe?
Critical Risk
- Anyone on the system can modify or replace this file.
- Every member of the group can modify this file.
- Any user can read this file — never use it for secrets such as keys or .env files.
- Even the owner cannot modify this file without changing permissions first.
- Unusual: a lower class has permissions the class above it lacks.
Common Use Cases
066 is uncommon in standard Linux setups. The closest widely used permission is chmod 666.
chmod 066 Command Examples
# Apply using octal mode
chmod 066 filename
# Apply using equivalent symbolic mode
chmod u=,g=rw,o=rw filename
# Recursive command warning:
chmod -R 066 /path/to/dir
# Note: -R applies the same mode to files and directories. Use find to treat them separately:
find /path/to/dir -type f -exec chmod 066 {} +
# Verify permissions
stat -c '%a %A %n' filename # Linux
stat -f '%Lp %Sp %N' filename # macOS
# Example ls -l output:
----rw-rw- 1 alice staff 1024 Jan 15 10:00 example.txtumask Relationship
A umask of 711 makes new directories 066 and new files 066. Test umask values with our interactive Umask Calculator.
Frequently Asked Questions
What does chmod 066 mean?
chmod 066 gives the owner no access, the group read/write, and everyone else read/write. In octal notation, the owner receives 0 (no access), the group receives 6 (read/write), and others receive 6 (read/write).
Is chmod 066 safe?
chmod 066 is classified as Critical Risk. Anyone on the system can modify or replace this file.
What is chmod 066 in symbolic notation?
In symbolic notation, chmod 066 is represented as ---rw-rw-. You can apply this permission using the equivalent symbolic command "chmod u=,g=rw,o=rw filename".
Related Permissions
Change one bit: