chmod 640 explained (rw-r-----)

chmod 640 sets the permissions to rw-r-----.

• Owner: read, write
• Group: read
• Others: no access

When to use it

Config files containing credentials that a service group needs to read.

Security note

Make sure the file's group is the service's group, otherwise the service cannot read it.

Tip: applying it to files and directories separately

Directories need the execute bit to be entered, files usually do not. Set them separately: find dir -type d -exec chmod 755 {} + and find dir -type f -exec chmod 644 {} +.

Other common modes