chmod 257 Permission Explained
Summary: chmod 257 gives the owner write, the group read/execute, and everyone else read/write/execute.
| Class | Read (4) | Write (2) | Execute (1) | Octal |
|---|---|---|---|---|
| Owner (u) | 2 | |||
| Group (g) | 5 | |||
| Others (o) | 7 |
chmod 257 filename
chmod 257 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) | 7 |
rwx |
Full access | Full access: list, enter, create, delete |
Is chmod 257 Safe?
Critical Risk
- Anyone on the system can modify or replace this file.
- 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
257 is uncommon in standard Linux setups. The closest widely used permission is chmod 755.
chmod 257 Command Examples
# Apply using octal mode
chmod 257 filename
# Apply using equivalent symbolic mode
chmod u=w,g=rx,o=rwx filename
# Recursive command warning:
chmod -R 257 /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 257 {} +
# Verify permissions
stat -c '%a %A %n' filename # Linux
stat -f '%Lp %Sp %N' filename # macOS
# Example ls -l output:
--w-r-xrwx 1 alice staff 1024 Jan 15 10:00 example.txtumask Relationship
A umask of 520 makes new directories 257. Test umask values with our interactive Umask Calculator.
Frequently Asked Questions
What does chmod 257 mean?
chmod 257 gives the owner write, the group read/execute, and everyone else read/write/execute. In octal notation, the owner receives 2 (write), the group receives 5 (read/execute), and others receive 7 (read/write/execute).
Is chmod 257 safe?
chmod 257 is classified as Critical Risk. Anyone on the system can modify or replace this file.
What is chmod 257 in symbolic notation?
In symbolic notation, chmod 257 is represented as -w-r-xrwx. You can apply this permission using the equivalent symbolic command "chmod u=w,g=rx,o=rwx filename".
Related Permissions
Change one bit: