Linux file permissions
Chmod Calculator · 400

chmod 400 (r--------)

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

400numeric
r--------symbolic
4 · 0 · 0owner · group · others
Commands
chmod 400 filename chmod u=r,g=,o= filename chmod -R 400 folder/ # apply to a folder and everything in it

Change any permission with the chmod calculator.

What chmod 400 means

WhoDigitLettersCan
Owner (user)4r--read
Group0---no access
Others0---no access

Each digit is the sum of read (4), write (2) and execute (1).

When to use 400

Read-only for the owner only (e.g. AWS .pem key files).

Related permissions

chmod 600see what 600 meanschmod 555see what 555 meanschmod 500see what 500 meanschmod 444see what 444 meanschmod 1777see what 1777 meanschmod 2755see what 2755 meanschmod 4755see what 4755 means

Questions

What does chmod 400 mean?

chmod 400 sets the permissions to r--------: the owner can read, the group can no access and others can no access.

When should I use 400?

Read-only for the owner only (e.g. AWS .pem key files).

What is 400 in symbolic form?

400 is r-------- (shown by ls -l as -r-------- for a file or dr-------- for a folder). The symbolic chmod command is chmod u=r,g=,o= file.