bash - 将 cronjob 错误通过管道发送到邮件

Question

我有一份 root 工作

0 0 * * * /usr/bin/time /path/to/mysqlbackup.sh | /bin/mail -s "MySQL Backup" "<a href="https://stackoverflow.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="39585d545057795c41585449555c175a5654" rel="noreferrer noopener nofollow">[email protected]</a>"

脚本运行时会回显一些信息，然后按预期通过电子邮件发送。

问题是，如果发生错误，错误不会发送到电子邮件，因此我无法捕获它。如果我查看 root 用户的邮件，我会看到类似

的错误

mysqldump: Got error: 2002: Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2) when trying to connect

如何将脚本产生的所有输出发送到我的电子邮件？

---

注释

计划任务

* * * * * (/usr/bin/time /root/utils/test.sh 2&>1) | /usr/bin/tee /tmp/cron.test | /bin/mail -s "test" "<a href="https://stackoverflow.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="b8cbcad7dadad1d6cbf8ddc0d9d5c8d4dd96dbd7d5" rel="noreferrer noopener nofollow">[email protected]</a>"

在 root 的邮件中发现消息

[root@example utils]# mail
Mail version 8.1 6/6/93.  Type ? for help.
"/var/spool/mail/root": 1 message 1 new
>N  1 root@example  Fri Oct 11 08:35  23/1025  "Cron <root@example> (/usr/bin/time /root/utils/test.sh 2&>1) | /usr/bin/tee /tmp/cron.test | /bin/mail -s "test" "<a href="https://stackoverflow.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="c0b3b2afa2a2a9aeb380a5b8a1adb0aca5eea3afad" rel="noreferrer noopener nofollow">[email protected]</a>""
& 
Message 1:
From <a href="https://stackoverflow.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="eb9984849fab8e938a869b878ec5888486" rel="noreferrer noopener nofollow">[email protected]</a>  Fri Oct 11 08:35:01 2013
Date: Fri, 11 Oct 2013 08:35:01 -0700
From: <a href="https://stackoverflow.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="f4869b9b80b4918c9599849891da979b99" rel="noreferrer noopener nofollow">[email protected]</a> (Cron Daemon)
To: <a href="https://stackoverflow.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="71031e1e05311409101c011d145f121e1c" rel="noreferrer noopener nofollow">[email protected]</a>
Subject: Cron <root@example> (/usr/bin/time /root/utils/test.sh 2&>1) | /usr/bin/tee /tmp/cron.test | /bin/mail -s "test" "<a href="https://stackoverflow.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="80f3f2efe2e2e9eef3c0e5f8e1edf0ece5aee3efed" rel="noreferrer noopener nofollow">[email protected]</a>"
Content-Type: text/plain; charset=UTF-8
Auto-Submitted: auto-generated
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>

Null message body; hope that's ok

/root/utils/test.sh的内容

echo "Starting backup at $(date)" 
mysql -u potato -e "show status" # produces error
FILE="/path/to/file.bak"
FILESIZE=`du -h $FILE | cut -f1`
echo $FILESIZE

/tmp/cron.test 为空

发送的电子邮件正文为空

Answer 1

基本上，您需要以与 STDOUT 相同的方式处理 STDERR。

通过管道将其输入 cron

0 0 * * * (/usr/bin/time /path/to/mysqlbackup.sh 2&>1) | /bin/mail -s "MySQL Backup" "<a href="https://stackoverflow.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="6d0c090004032d08150c001d0108430e0200" rel="noreferrer noopener nofollow">[email protected]</a>" 

这适用于 Ubuntu，您报告它不适用于您(空邮件正文)。我有兴趣深入研究这一点，但与此同时......

调整脚本

您可以通过重定向 STDERR(至少对于 STDOUT 的该命令)来使脚本仅打印到 STDOUT

echo "Starting backup at $(date)" 
mysql -u potato -e "show status" 2>&1 # produces error we want, so redirect it
FILE="/path/to/file.bak"
FILESIZE=`du -h $FILE | cut -f1`
echo $FILESIZE

如果您希望将脚本中的任何错误发送到 STDOUT，您可以通过在脚本顶部添加以下内容来将 STDERR 全局重定向到 STDOUT:

exec 2>&1

玩具示例

job.sh

#prints out to STDOUT and STDERR
echo good
echo error >&2
echo good

script.sh

#this runs job.sh redirecting STDERR to STDOUT
sh job.sh 2>&1

现在运行 job.sh，通过各种重定向显示其打印到 STDOUT 和 STDERR

$sh job.sh > /dev/null 
error
$sh job.sh 2> /dev/null 
good
good

运行 script.sh 显示它只打印到 STDOUT，即使 job.sh 正在打印到 STDERR

$sh script.sh > /dev/null 
$sh script.sh 2> /dev/null 
good
error
good