File permissions

Cheat sheet

• ls -l permissions and owner
• namei -l /path/to/file where along the path permissions are lost
• chmod 640 file owner rw, group r
• chmod 600 secret owner only
• chmod 755 script executable for everyone
• chmod u+x,go-w file symbolic
• chmod 2775 dir SGID — a shared group
• chmod 1777 dir sticky — only the owner can delete
• chown user:grp file see chmod-chown
• find / -perm -4000 -type f 2>/dev/null audit SUID