chmod 451 Permission Explained
Summary: chmod 451 gives the owner read, the group read/execute, and everyone else execute.
| Class | Read (4) | Write (2) | Execute (1) | Octal |
|---|---|---|---|---|
| Owner (u) | 4 | |||
| Group (g) | 5 | |||
| Others (o) | 1 |
chmod 451 filename
chmod 451 Breakdown
| Class | Digit | Symbolic | On a file | On a directory |
|---|---|---|---|---|
| Owner (u) | 4 |
r-- |
Read only | Can list names, but not enter |
| Group (g) | 5 |
r-x |
Read and execute | Can list and enter |
| Others (o) | 1 |
--x |
Execute only | Can enter (cd) but not list contents |
Is chmod 451 Safe?
Low Risk
- 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
451 is uncommon in standard Linux setups. The closest widely used permission is chmod 555.
chmod 451 Command Examples
# Apply using octal mode
chmod 451 filename
# Apply using equivalent symbolic mode
chmod u=r,g=rx,o=x filename
# Recursive command warning:
chmod -R 451 /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 451 {} +
# Verify permissions
stat -c '%a %A %n' filename # Linux
stat -f '%Lp %Sp %N' filename # macOS
# Example ls -l output:
-r--r-x--x 1 alice staff 1024 Jan 15 10:00 example.txtumask Relationship
A umask of 326 makes new directories 451. Test umask values with our interactive Umask Calculator.
Frequently Asked Questions
What does chmod 451 mean?
chmod 451 gives the owner read, the group read/execute, and everyone else execute. In octal notation, the owner receives 4 (read), the group receives 5 (read/execute), and others receive 1 (execute).
Is chmod 451 safe?
chmod 451 is classified as Low Risk. Even the owner cannot modify this file without changing permissions first.
What is chmod 451 in symbolic notation?
In symbolic notation, chmod 451 is represented as r--r-x--x. You can apply this permission using the equivalent symbolic command "chmod u=r,g=rx,o=x filename".
Related Permissions
Change one bit: