chmod 550 Permission Explained

Octal

550

Symbolic

r-xr-x---

Binary

101 101 000

Risk Level

Low Risk

Summary: chmod 550 gives the owner read/execute, the group read/execute, and everyone else no access.

Class	Read (4)	Write (2)	Execute (1)	Octal
Owner (u)				5
Group (g)				5
Others (o)				0

setuid (4) setgid (2) sticky bit (1)

Octal

Symbolic

Target File / Path

-R Recursive -v Verbose

550

r-xr-x---

Owner: read/execute · Group: read/execute · Others: no access

chmod 550 filename

Low Risk Even the owner cannot modify this file without changing permissions first.

View the full chmod 550 guide →

chmod 550 Breakdown

Class	Digit	Symbolic	On a file	On a directory
Owner (u)	`5`	`r-x`	Read and execute	Can list and enter
Group (g)	`5`	`r-x`	Read and execute	Can list and enter
Others (o)	`0`	`---`	No access	Cannot list, enter, or modify

Is chmod 550 Safe?

Low Risk

Even the owner cannot modify this file without changing permissions first.

Common Use Cases

550 is uncommon in standard Linux setups. The closest widely used permission is chmod 750.

chmod 550 Command Examples

# Apply using octal mode
chmod 550 filename

# Apply using equivalent symbolic mode
chmod u=rx,g=rx,o= filename

# Recursive command warning:
chmod -R 550 /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 550 {} +

# Verify permissions
stat -c '%a %A %n' filename    # Linux
stat -f '%Lp %Sp %N' filename   # macOS

# Example ls -l output:
-r-xr-x--- 1 alice staff 1024 Jan 15 10:00 example.txt

umask Relationship

A umask of 227 makes new directories 550. Test umask values with our interactive Umask Calculator.

Frequently Asked Questions

What does chmod 550 mean?

chmod 550 gives the owner read/execute, the group read/execute, and everyone else no access. In octal notation, the owner receives 5 (read/execute), the group receives 5 (read/execute), and others receive 0 (no access).

Is chmod 550 safe?

chmod 550 is classified as Low Risk. Even the owner cannot modify this file without changing permissions first.

What is chmod 550 in symbolic notation?

In symbolic notation, chmod 550 is represented as r-xr-x---. You can apply this permission using the equivalent symbolic command "chmod u=rx,g=rx,o= filename".