linux - 电子邮件中的所有行一起运行

Question

这应该相对简单，但我以前从未遇到过它，现在我摸不着头脑。

简单的脚本:

echo `tail /var/log/qmailcheck.log` >> $EMAIL
cat $EMAIL | mail -s "Daily server report from server.ca" email@here.com

(我知道我在 tail cmd 周围遗漏了一组刻度线，只是想让事情看起来正确)

问题是，虽然我拖出的日志文件的每个条目都有一个新行，但发送的电子邮件将所有内容都放在一行中，所以不是这样:

Mon Feb 4 11:05:01 MST 2013-- Check Completed Successfully<br/>
Mon Feb 4 11:10:01 MST 2013-- Check Completed Successfully<br/>
Mon Feb 4 11:15:01 MST 2013-- Check Completed Successfully<br/>
Mon Feb 4 11:20:01 MST 2013-- Check Completed Successfully<br/>
Mon Feb 4 11:25:01 MST 2013-- Check Completed Successfully

我明白了:
Mon Feb 4 11:05:01 MST 2013-- Check Completed Successfully Mon Feb 4 11:10:01 MST 2013-- Check Completed Successfully Mon Feb 4 11:15:01 MST 2013-- Check Completed Successfully Mon Feb 4 11:20:01 MST 2013-- Check Completed Successfully Mon Feb 4 11:25:01 MST 2013-- Check Completed Successfully

该脚本还从许多其他命令中回显，它们似乎也出现在一行中，我以前这样做过但从来没有遇到过问题，我错过了什么？

这是完整的脚本:

ERROR=/tmp/errorlog
RECIP=$(cat /root/bin/emailrec)

echo Hi, this email to inform you of any potential issues with the server.bla qmail mail server > /tmp/demail

grep pls /var/log/qmailcheck.log > /tmp/errorlog

if [ ! -s $ERROR ] ; then
    echo There are no errors in the qmailcheck log file >> /tmp/demail
    echo Here are the last 10 lines of the current qmailcheck log file: >> /tmp/demail
    tail /var/log/qmailcheck.log >> /tmp/demail
else
    echo The log file for the qmail check script contains the following errors: >> /tmp/demail
    cat $ERROR >> /tmp/demail
    echo You should have also received an email which will better explain the error >> /tmp/demail
    echo Check the time of the error above to determine when the email was sent >> /tmp/demail
fi
MAIL=$(/var/qmail/bin/qmail-qstat | grep "queue:" | awk '{ print $4 }')
echo There are $MAIL messages in the mail queue >> /tmp/demail

echo File system usage is currently at `df -h |grep vzfs | awk '{ print $5}'` >> /tmp/demail


cat /tmp/demail | mail -s "Daily server report from server.bla" $RECIP

Answer 1

这就是您在不需要 echo 和 命令替换时获得的结果。

唯一的区别

echo `command args...`

和

command args

是换行符被折叠(代码更难阅读)。只需使用

tail /var/log/qmailcheck.log | mail -s ....

(如果你想使用一个中间文件，那么你也可以在没有 echo 或反引号的情况下使用它)。

请注意，还有另一种命令替换样式:$(command...)，它消除了嵌套引用的问题并且通常更具可读性。每当您需要命令替换时，您都可以使用这种样式而不是反引号。