touch auth.log
root@ubuntu:/work# ls -l auth.log -rw-r--r-- 1 root root 0 Feb 18 19:27 auth.log
chown syslog.adm auth.log
root@ubuntu:/work# ls -l auth.log-rw-r--r-- 1 syslog adm 0 Feb 18 19:27 auth.log