我的 CentOS 6 机器老是自动关机。我怎样才能确定是什么原因导致它这样做？我安装了它，lm_sensors并在它自动关机前不久查看了 CPU 温度，我认为这不是问题所在。除此之外，我不知道该去哪里找？！
这是当时 /var/log/messages 中发生的情况：
<previous message is from when I powered the machine on>
Jan 20 21:02:52 dedicated1 init: tty (/dev/tty1) main process (3462) killed by TERM signal
Jan 20 21:02:52 dedicated1 init: tty (/dev/tty2) main process (3464) killed by TERM signal
Jan 20 21:02:52 dedicated1 init: tty (/dev/tty3) main process (3466) killed by TERM signal
Jan 20 21:02:52 dedicated1 init: tty (/dev/tty4) main process (3468) killed by TERM signal
Jan 20 21:02:52 dedicated1 init: tty (/dev/tty5) main process (3470) killed by TERM signal
Jan 20 21:02:52 dedicated1 init: tty (/dev/tty6) main process (3472) killed by TERM signal
Jan 20 21:02:54 dedicated1 abrtd: Got signal 15, exiting
Jan 20 21:02:54 dedicated1 acpid: exiting
Jan 20 21:02:55 dedicated1 ntpd[2402]: ntpd exiting on signal 15
Jan 20 21:02:55 dedicated1 init: Disconnected from system bus
Jan 20 21:02:55 dedicated1 console-kit-daemon[5523]: WARNING: no sender#012
Jan 20 21:02:55 dedicated1 rpcbind: rpcbind terminating on signal. Restart with "rpcbind -w"
Jan 20 21:02:55 dedicated1 auditd[1985]: The audit daemon is exiting.
Jan 20 21:02:55 dedicated1 kernel: type=1305 audit(1579554175.663:69): audit_pid=0 old=1985 auid=4294967295 ses=4294967295 res=1
Jan 20 21:02:55 dedicated1 kernel: type=1305 audit(1579554175.770:70): audit_enabled=0 old=1 auid=4294967295 ses=4294967295 res=1
Jan 20 21:02:55 dedicated1 kernel: Kernel logging (proc) stopped.
Jan 20 21:02:55 dedicated1 rsyslogd: [origin software="rsyslogd" swVersion="5.8.10" x-pid="2007" x-info="http://www.rsyslog.com"] exiting on signal 15.
<next message is from when I powered the machine back on>
这有什么用吗？如果没有，我下一步应该去哪里找？
last -x | grep shutdown给出：
shutdown system down 2.6.32-754.25.1. Tue Jan 21 12:07 - 14:50 (02:42)
shutdown system down 2.6.32-754.25.1. Mon Jan 20 23:31 - 11:55 (12:24)
shutdown system down 2.6.32-754.25.1. Mon Jan 20 21:02 - 22:58 (01:55)
shutdown system down 2.6.32-754.25.1. Mon Jan 20 20:36 - 20:48 (00:11)
shutdown system down 2.6.32-754.25.1. Mon Jan 20 15:00 - 20:02 (05:01)
shutdown system down 2.6.32-754.24.3. Thu Jan 2 08:28 - 08:31 (00:02)