chmod 340 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

340

Symbolic

-wxr-----

Binary

011 100 000

Risk Level

Low Risk

Summary: chmod 340 gives the owner write/execute, the group read, and everyone else no access.

Class	Read (4)	Write (2)	Execute (1)	Octal
Owner (u)				3
Group (g)				4
Others (o)				0

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

Octal

Symbolic

Target File / Path

-R Recursive -v Verbose

340

-wxr-----

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

chmod 340 filename

Low Risk Scripts need read permission to run; only compiled binaries can be executed without it.

View the full chmod 340 guide →

chmod 340 Breakdown

Class	Digit	Symbolic	On a file	On a directory
Owner (u)	`3`	`-wx`	Write and execute	Can enter and create/delete files, but not list
Group (g)	`4`	`r--`	Read only	Can list names, but not enter
Others (o)	`0`	`---`	No access	Cannot list, enter, or modify

Is chmod 340 Safe?

Low Risk

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

340 is uncommon in standard Linux setups. The closest widely used permission is chmod 740.

chmod 340 Command Examples

# Apply using octal mode
chmod 340 filename

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

# Recursive command warning:
chmod -R 340 /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 340 {} +

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

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

umask Relationship

A umask of 437 makes new directories 340. Test umask values with our interactive Umask Calculator.

Frequently Asked Questions

What does chmod 340 mean?

chmod 340 gives the owner write/execute, the group read, and everyone else no access. In octal notation, the owner receives 3 (write/execute), the group receives 4 (read), and others receive 0 (no access).

Is chmod 340 safe?

chmod 340 is classified as Low Risk. Scripts need read permission to run; only compiled binaries can be executed without it.

What is chmod 340 in symbolic notation?

In symbolic notation, chmod 340 is represented as -wxr-----. You can apply this permission using the equivalent symbolic command "chmod u=wx,g=r,o= filename".