需求描述:
早上设置了ntp客户端的定时任务,发现不断的有You have new mail in /var/spool/mail/root这种提示.
然后,就看了具体的文件,由于ntpdate是每分钟执行,执行的结果,都输出到mail邮件里面了.所以,担心
这个给撑爆了,就预先放置吧,看看如何在crontab不进行标准或错误输出.
操作过程:
[[email protected] mail]# crontab -l
*/1 * * * * /usr/sbin/ntpdate 192.168.53.22
[[email protected] mail]# crontab -l #一分钟之后,再次执行就报了mail的提示.
*/1 * * * * /usr/sbin/ntpdate 192.168.53.22
You have new mail in /var/spool/mail/root
[[email protected] mail]# ls -l /var/spool/mail/root
-rw------- 1 root mail 188542 Aug 8 10:59 /var/spool/mail/root #最近刚有新的信息输入
You have new mail in /var/spool/mail/root
[[email protected] mail]# more /var/spool/mail/root #查看文件的内容就是发送邮件的信息和执行命令的输出.就是发送邮件的信息,把你执行的命令结果,发送出去.
From [email protected] Tue Aug 7 17:29:36 2018
Return-Path: <[email protected]>
X-Original-To: root
Delivered-To: [email protected]
Received: by testvm02.localdomain (Postfix, from userid 0)
id A4E68440BC; Tue, 7 Aug 2018 17:29:36 +0800 (CST)
From: [email protected] (Cron Daemon)
To: [email protected]
Subject: Cron <[email protected]> ntpdate 192.168.53.22
Content-Type: text/plain; charset=UTF-8
Auto-Submitted: auto-generated
X-Cron-Env: <LANG=en_US.UTF-8>
X-Cron-Env: <SHELL=/bin/sh>
X-Cron-Env: <HOME=/root>
X-Cron-Env: <PATH=/usr/bin:/bin>
X-Cron-Env: <LOGNAME=root>
X-Cron-Env: <USER=root>
Message-Id: <[email protected]>
Date: Tue, 7 Aug 2018 17:29:36 +0800 (CST)
/bin/sh: ntpdate: command not found
From [email protected] Tue Aug 7 17:30:01 2018
Return-Path: <[email protected]>
X-Original-To: root
Delivered-To: [email protected]
Received: by testvm02.localdomain (Postfix, from userid 0)
id A83D7440BD; Tue, 7 Aug 2018 17:30:01 +0800 (CST)
From: [email protected] (Cron Daemon)
To: [email protected]
Subject: Cron <[email protected]> ntpdate 192.168.53.22
Content-Type: text/plain; charset=UTF-8
Auto-Submitted: auto-generated
X-Cron-Env: <LANG=en_US.UTF-8>
[[email protected] mail]# crontab -e
crontab: installing new crontab
[[email protected] mail]# crontab -l
*/1 * * * * /usr/sbin/ntpdate 192.168.53.22 >/dev/null 2>&1
备注:这样执行就没有标准和错误输出了.
[[email protected] mail]# ls -l root
-rw------- 1 root mail 191901 Aug 8 11:03 root
[[email protected] mail]# ls -l root
-rw------- 1 root mail 191901 Aug 8 11:03 root
[[email protected] mail]# ls -l root
-rw------- 1 root mail 191901 Aug 8 11:03 root
[[email protected] mail]# date
Wed Aug 8 11:05:05 CST 2018
备注:该文件中的内容没有增加,以后也不会出现不断增加,可能会撑爆磁盘的情况了.
另:在其他的博客中设置echo "unset MAILCHECK">>/etc/profile 可以不检查mail目录中的内容,但是只是不检查发送邮件,但是root的内容还在增加.
[[email protected] mail]# crontab -l
MAILTO=""
*/1 * * * * /usr/sbin/ntpdate 192.168.53.22
*/1 * * * * /usr/sbin/ntpdate 192.168.53.22 >/dev/null 2>&1
备注:这样的话/var/spool/mail中root文件就不会在增加了,否则即使是unset MAILCHECK不提示有邮件了,但是这个文件还是在增加.