olemus
Unixi-laadsete süsteemide turvameede: krüpteeritud paroolide faili juurde pääseb ainult süsteemiülem
= a security measure for Unix-like systems: encrypted password file is accessible only by the system administrator

ülevaateid
https://en.wikipedia.org/wiki/Passwd#Shadow_file

https://tldp.org/HOWTO/Shadow-Password-HOWTO-2.html

https://www.cyberciti.biz/faq/understanding-etcshadow-file/

https://man7.org/linux/man-pages/man5/shadow.5.html