chmod 512 Permission Explained
Summary: chmod 512 gives the owner read/execute, the group execute, and everyone else write.
| Class | Read (4) | Write (2) | Execute (1) | Octal |
|---|---|---|---|---|
| Owner (u) | 5 | |||
| Group (g) | 1 | |||
| Others (o) | 2 |
chmod 512 filename
chmod 512 Breakdown
| Class | Digit | Symbolic | On a file | On a directory |
|---|---|---|---|---|
| Owner (u) | 5 |
r-x |
Read and execute | Can list and enter |
| Group (g) | 1 |
--x |
Execute only | Can enter (cd) but not list contents |
| Others (o) | 2 |
-w- |
Write only (rarely useful) | No practical effect without x |
Is chmod 512 Safe?
Critical Risk
- Anyone on the system can modify or replace this file.
- 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
512 is uncommon in standard Linux setups. The closest widely used permission is chmod 500.
chmod 512 Command Examples
# Apply using octal mode
chmod 512 filename
# Apply using equivalent symbolic mode
chmod u=rx,g=x,o=w filename
# Recursive command warning:
chmod -R 512 /path/to/dir
# Note: -R applies the same mode to files and directories. Use find to treat them separately:
find /path/to/dir -type d -exec chmod 512 {} +
# Verify permissions
stat -c '%a %A %n' filename # Linux
stat -f '%Lp %Sp %N' filename # macOS
# Example ls -l output:
-r-x--x-w- 1 alice staff 1024 Jan 15 10:00 example.txtumask Relationship
A umask of 265 makes new directories 512. Test umask values with our interactive Umask Calculator.
Frequently Asked Questions
What does chmod 512 mean?
chmod 512 gives the owner read/execute, the group execute, and everyone else write. In octal notation, the owner receives 5 (read/execute), the group receives 1 (execute), and others receive 2 (write).
Is chmod 512 safe?
chmod 512 is classified as Critical Risk. Anyone on the system can modify or replace this file.
What is chmod 512 in symbolic notation?
In symbolic notation, chmod 512 is represented as r-x--x-w-. You can apply this permission using the equivalent symbolic command "chmod u=rx,g=x,o=w filename".
Related Permissions
Change one bit: