读取日志bash脚本时出错

Question

我正在写的bash脚本有问题。我想读取一个日志文件，并对输出做一些处理。但问题是，它每次记录两行而不是一行。所以每次我得到输出的副本，而不是一行。

#!/bin/bash
##############

logfile=/var/atlassian/application-data/jira/log/atlassian-ing-security.log
counter_a=0
counter_b=0

tail -fn0 /var/atlassian/application-data/jira/log/atlassian-jira-   security.log | \
while read line ; do
    echo "$line" | grep "FAILED"
    if [ $? = 0 ]
    then
        echo "API action FAILED" >> $logfile
        counter_a=$((counter_a+1))
        echo "Total of $counter_a API actions FAILED" >> $logfile
    else
        echo "API action SUCCESFULL" >> $logfile
        counter_b=$((counter_b+1))
        echo "Total of $counter_b API actions SUCCESFULL" >> $logfile
    fi
 done

这是我在脚本中使用的输出：

2016-07-05 20:11:28,335 http-bio-8080-exec-2917 anonymous 1211x943864x1 - 10.000.000.113,10.000.105.000 /rest/api/2/search HttpSession created [10n1nec]
2016-07-05 20:11:28,381 http-bio-8080-exec-2917 AABBCC 1211x943864x1 - 10.000.000.000,10.000.105.000 /rest/api/2/search The user 'AABBCC' has PASSED authentication.

如何删除脚本中的每一次第二行？

谢谢!

Answer 1

问题是grep的输出也会变成你的脚本的标准输出。您可以简单地将其静默：

if echo "$line" | grep -q FAILED; then
    echo "API action FAILED" >> $logfile
    counter_a=$((counter_a+1))
    echo "Total of $counter_a API actions FAILED" >> $logfile
else
    echo "API action SUCCESFULL" >> $logfile
    counter_b=$((counter_b+1))
    echo "Total of $counter_b API actions SUCCESFULL" >> $logfile
fi

但是，更好的方法是避免在每一行上调用(相对)昂贵的grep，而使用shell本身来检测匹配。

tail ... | {
  while read line ; do
    if [[ $line = *FAILED* ]]; then
    then
        echo "API action FAILED"
        counter_a=$((counter_a+1))
    else
        echo "API action SUCCESSFUL"
        counter_b=$((counter_b+1))
    fi
  done
  # You probably want to execute these just once, after the entire
  # file has been processed.
  echo "Total of $counter_b API actions SUCCESSFUL"
  echo "Total of $counter_a API actions FAILED"
} >> "$logfile"