Linux Permissions

chmod Number Reference

chmod 644 file

Position	Applies To
First digit	Owner permissions
Second digit	Group permissions
Third digit	Others permissions

Value	Permission
4	read (r)
2	write (w)
1	execute (x)
0	no permission (-)

Examples:

644 = rw-r--r--   Owner can read/write, Group/Others read-only
700 = rwx------   Only Owner can read/write/execute
755 = rwxr-xr-x   Owner full access, Group/Others can read and execute

Docker + Security Configuration Example

To prevent regular users from reading config files directly while still allowing Docker to mount them:

docker-compose.yml  → 700 (only owner can read/write/execute)
config directory/   → 600 (only owner can read/write)
data files inside   → 644 (owner read/write, others read-only)

Regular users can't read the config directly, but Docker containers can mount and use the data because they run with the appropriate user context.