chmod 666 explained (rw-rw-rw-)

chmod 666 sets the permissions to rw-rw-rw-.

• Owner: read, write
• Group: read, write
• Others: read, write

When to use it

Rarely used. World-writable files, sometimes seen for shared sockets or device nodes.

Security note

Anyone can overwrite the file. Prefer a group-based mode such as 664 or 660.

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