chmod 155 Permission Explained

Notice: This is an unusual permission set: some classes have more access than the class above them. It is rarely correct in practice.

Octal

155

Symbolic

--xr-xr-x

Binary

001 101 101

Risk Level

Low Risk

Summary: chmod 155 gives the owner execute, the group read/execute, and everyone else read/execute.

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

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

Octal

Symbolic

Target File / Path

-R Recursive -v Verbose

155

--xr-xr-x

Owner: execute · Group: read/execute · Others: read/execute

chmod 155 filename

Low Risk Any user can read this file — never use it for secrets such as keys or .env files.

View the full chmod 155 guide →

chmod 155 Breakdown

Class	Digit	Symbolic	On a file	On a directory
Owner (u)	`1`	`--x`	Execute only	Can enter (cd) but not list contents
Group (g)	`5`	`r-x`	Read and execute	Can list and enter
Others (o)	`5`	`r-x`	Read and execute	Can list and enter

Is chmod 155 Safe?

Low Risk

Any user can read this file — never use it for secrets such as keys or .env files.
Even the owner cannot modify this file without changing permissions first.
Scripts need read permission to run; only compiled binaries can be executed without it.
Unusual: a lower class has permissions the class above it lacks.

Common Use Cases

155 is uncommon in standard Linux setups. The closest widely used permission is chmod 555.

chmod 155 Command Examples

# Apply using octal mode
chmod 155 filename

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

# Recursive command warning:
chmod -R 155 /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 155 {} +

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

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

umask Relationship

A umask of 622 makes new directories 155. Test umask values with our interactive Umask Calculator.

Frequently Asked Questions

What does chmod 155 mean?

chmod 155 gives the owner execute, the group read/execute, and everyone else read/execute. In octal notation, the owner receives 1 (execute), the group receives 5 (read/execute), and others receive 5 (read/execute).

Is chmod 155 safe?

chmod 155 is classified as Low Risk. Any user can read this file — never use it for secrets such as keys or .env files.

What is chmod 155 in symbolic notation?

In symbolic notation, chmod 155 is represented as --xr-xr-x. You can apply this permission using the equivalent symbolic command "chmod u=x,g=rx,o=rx filename".