chmod 255 Permission Explained
Summary: chmod 255 gives the owner write, the group read/execute, and everyone else read/execute.
| Class | Read (4) | Write (2) | Execute (1) | Octal |
|---|---|---|---|---|
| Owner (u) | 2 | |||
| Group (g) | 5 | |||
| Others (o) | 5 |
chmod 255 filename
chmod 255 Breakdown
| Class | Digit | Symbolic | On a file | On a directory |
|---|---|---|---|---|
| Owner (u) | 2 |
-w- |
Write only (rarely useful) | No practical effect without x |
| Group (g) | 5 |
r-x |
Read and execute | Can list and enter |
| Others (o) | 5 |
r-x |
Read and execute | Can list and enter |
Is chmod 255 Safe?
Low Risk
- Any user can read this file — never use it for secrets such as keys or .env files.
- Unusual: a lower class has permissions the class above it lacks.
Common Use Cases
255 is uncommon in standard Linux setups. The closest widely used permission is chmod 755.
chmod 255 Command Examples
# Apply using octal mode
chmod 255 filename
# Apply using equivalent symbolic mode
chmod u=w,g=rx,o=rx filename
# Recursive command warning:
chmod -R 255 /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 255 {} +
# Verify permissions
stat -c '%a %A %n' filename # Linux
stat -f '%Lp %Sp %N' filename # macOS
# Example ls -l output:
--w-r-xr-x 1 alice staff 1024 Jan 15 10:00 example.txtumask Relationship
A umask of 522 makes new directories 255. Test umask values with our interactive Umask Calculator.
Frequently Asked Questions
What does chmod 255 mean?
chmod 255 gives the owner write, the group read/execute, and everyone else read/execute. In octal notation, the owner receives 2 (write), the group receives 5 (read/execute), and others receive 5 (read/execute).
Is chmod 255 safe?
chmod 255 is classified as Low Risk. Any user can read this file — never use it for secrets such as keys or .env files.
What is chmod 255 in symbolic notation?
In symbolic notation, chmod 255 is represented as -w-r-xr-x. You can apply this permission using the equivalent symbolic command "chmod u=w,g=rx,o=rx filename".
Related Permissions
Change one bit: