chmod 540 Permission Explained
Summary: chmod 540 gives the owner read/execute, the group read, and everyone else no access.
| Class | Read (4) | Write (2) | Execute (1) | Octal |
|---|---|---|---|---|
| Owner (u) | 5 | |||
| Group (g) | 4 | |||
| Others (o) | 0 |
chmod 540 filename
chmod 540 Breakdown
| Class | Digit | Symbolic | On a file | On a directory |
|---|---|---|---|---|
| Owner (u) | 5 |
r-x |
Read and execute | Can list and enter |
| Group (g) | 4 |
r-- |
Read only | Can list names, but not enter |
| Others (o) | 0 |
--- |
No access | Cannot list, enter, or modify |
Is chmod 540 Safe?
Low Risk
- Even the owner cannot modify this file without changing permissions first.
Common Use Cases
540 is uncommon in standard Linux setups. The closest widely used permission is chmod 740.
chmod 540 Command Examples
# Apply using octal mode
chmod 540 filename
# Apply using equivalent symbolic mode
chmod u=rx,g=r,o= filename
# Recursive command warning:
chmod -R 540 /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 540 {} +
# Verify permissions
stat -c '%a %A %n' filename # Linux
stat -f '%Lp %Sp %N' filename # macOS
# Example ls -l output:
-r-xr----- 1 alice staff 1024 Jan 15 10:00 example.txtumask Relationship
A umask of 237 makes new directories 540. Test umask values with our interactive Umask Calculator.
Frequently Asked Questions
What does chmod 540 mean?
chmod 540 gives the owner read/execute, the group read, and everyone else no access. In octal notation, the owner receives 5 (read/execute), the group receives 4 (read), and others receive 0 (no access).
Is chmod 540 safe?
chmod 540 is classified as Low Risk. Even the owner cannot modify this file without changing permissions first.
What is chmod 540 in symbolic notation?
In symbolic notation, chmod 540 is represented as r-xr-----. You can apply this permission using the equivalent symbolic command "chmod u=rx,g=r,o= filename".
Related Permissions
Change one bit: