/etc/shadow

An /etc/shadow file can be created from an /etc/passwd file with pwconv.

Group-owner shadow

The group-owner of /etc/shadow is shadow. Some programs that need to be able to access the file are setgid shadow.

The following shell construct finds such files which are in the $PATH variable:

# ( IFS=:
  for path in $PATH; do
      find $path -type f -group shadow -perm -g=s
  done
)
/usr/sbin/unix_chkpwd
/usr/bin/chage
/usr/bin/expiry