chmod 600 explained (rw-------)

chmod 600 sets the permissions to rw-------.

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

When to use it

Private keys (~/.ssh/id_ed25519), .env files and other secrets.

Security note

Only the owner can access it. SSH refuses to use a private key that others can read.

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