root@arthas:/var/log# ls --sort=time -l mail.*
-rw-r----- 1 root adm  472710 May 31 06:41 mail.info
-rw-r--r-- 1 root adm  784374 May 31 06:41 mail.log
-rw-r--r-- 1 root adm   19718 May 31 06:36 mail.warn
-rw-r--r-- 1 root adm   19178 May 28 08:36 mail.err
-rw-r----- 1 root adm  966522 May 27 06:25 mail.info.1
-rw-r--r-- 1 root adm 1425985 May 27 06:25 mail.log.1
-rw-r--r-- 1 root adm  286389 May 24 08:23 mail.err.1
-rw-r--r-- 1 root adm  286389 May 24 08:23 mail.warn.1