chmod 000 Permission Explained: No Permissions
Summary: Only root can access it.
| Class | Read (4) | Write (2) | Execute (1) | Octal |
|---|---|---|---|---|
| Owner (u) | 0 | |||
| Group (g) | 0 | |||
| Others (o) | 0 |
chmod 000 filename
chmod 000 Breakdown
| Class | Digit | Symbolic | On a file | On a directory |
|---|---|---|---|---|
| Owner (u) | 0 |
--- |
No access | Cannot list, enter, or modify |
| Group (g) | 0 |
--- |
No access | Cannot list, enter, or modify |
| Others (o) | 0 |
--- |
No access | Cannot list, enter, or modify |
Is chmod 000 Safe?
Restrictive
- Even the owner cannot modify this file without changing permissions first.
- No one except root can access this file.
When not to use it
- Any file or directory needed for normal operation
Common Use Cases
- Temporarily locking down compromised or suspicious files during incident response
- Testing application error-handling when encountering unreadable resources
chmod 000 Command Examples
# Apply using octal mode
chmod 000 filename
# Apply using equivalent symbolic mode
chmod u=,g=,o= filename
# Recursive command warning:
chmod -R 000 /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 000 {} +
# Verify permissions
stat -c '%a %A %n' filename # Linux
stat -f '%Lp %Sp %N' filename # macOS
# Example ls -l output:
---------- 1 alice staff 1024 Jan 15 10:00 example.txtumask Relationship
A umask of 777 makes new directories 000 and new files 000. Test umask values with our interactive Umask Calculator.
Frequently Asked Questions
What does chmod 000 mean?
Only root can access it. In octal notation, the owner receives 0 (no access), the group receives 0 (no access), and others receive 0 (no access).
Is chmod 000 safe?
chmod 000 is classified as Restrictive. Even the owner cannot modify this file without changing permissions first.
What is chmod 000 in symbolic notation?
In symbolic notation, chmod 000 is represented as ---------. You can apply this permission using the equivalent symbolic command "chmod u=,g=,o= filename".
Can root still read a chmod 000 file?
Yes. The Linux root superuser bypasses standard file read and write permission checks governed by DAC (Discretionary Access Control). Root can read from and write to a chmod 000 file without changing permissions first. However, root still cannot execute a 000 file without adding an execute bit.
Related Permissions
Change one bit: