shell脚本中打印所有匹配某些关键字符的行或前后各N行

[root@mq-master02 ~]# echo "abcd"
abcd
[root@mq-master02 ~]# echo "ab\ncd"
ab\ncd
[root@mq-master02 ~]# echo "ab \n cd"
ab \n cd
[root@mq-master02 ~]# echo -e "ab\ncd"
ab
cd
[root@mq-master02 ~]# echo -e "ab \n cd"
ab 
 cd
[root@mq-master02 ~]# echo -e "ab \n cd \n \n df"
ab 
 cd 
 
 df
 [root@mq-master02 ~]# echo -e "ab\ncd \n \ndf"   
ab
cd 
 
df

[root@mq-master02 ~]# cat /opt/test 
192.168.10.11
Don't worry! main is running!
192.168.10.12
Don't worry! main is running!
192.168.10.13
It's so bad! main is failed!
192.168.10.14
Don't worry! main is running!
192.168.10.15
Don't worry! main is running!
192.168.10.16
It's so bad! main is failed!
192.168.10.17
Don't worry! main is running!
192.168.10.18
Don't worry! main is running!
192.168.10.19
Don't worry! main is running!
192.168.10.20
Don't worry! main is running!
192.168.10.21
Don't worry! main is running!
192.168.10.12
Don't worry! main is running!

1）打印/opt/test中所有匹配"main is failed"的行
[root@mq-master02 ~]# cat /opt/test |grep "main is failed"
It's so bad! main is failed!
It's so bad! main is failed!
[root@mq-master02 ~]# sed -n '/main is failed/p' /opt/test
It's so bad! main is failed!
It's so bad! main is failed!

2）打印/opt/test中所有匹配"main is failed"的行及其前1行
[root@mq-master02 ~]# cat /opt/test |grep "main is failed" -B1   
192.168.10.13
It's so bad! main is failed!
--
192.168.10.16
It's so bad! main is failed!

3）打印/opt/test中所有匹配"main is failed"的行及其后1行
[root@mq-master02 ~]# cat /opt/test |grep "main is failed" -A1
It's so bad! main is failed!
192.168.10.14
--
It's so bad! main is failed!
192.168.10.17

4）打印/opt/test中所有匹配"main is failed"的行及其前后各1行
[root@mq-master02 ~]# cat /opt/test |grep "main is failed" -C1
192.168.10.13
It's so bad! main is failed!
192.168.10.14
--
192.168.10.16
It's so bad! main is failed!
192.168.10.17

5）把/opt/test中所有匹配"main is failed"的行及其前1行的结果打印到/root/result.log中，并加上时间
[root@mq-master02 ~]# echo -e "$(date)\n$(cat /opt/test|grep "main is failed" -B1)"> /root/result.log 
[root@mq-master02 ~]# cat /root/result.log
Wed Oct 10 20:34:15 CST 2018
192.168.10.13
It's so bad! main is failed!
--
192.168.10.16
It's so bad! main is failed!

[root@mq-master02 ~]# echo -e "$(date)\n$(cat /opt/test|grep "main is failed" -B1) \n" > /root/result.log
[root@mq-master02 ~]# echo -e "$(date)\n$(cat /opt/test|grep "main is failed" -B1) \n" >> /root/result.log
[root@mq-master02 ~]# echo -e "$(date)\n$(cat /opt/test|grep "main is failed" -B1) \n" >> /root/result.log
[root@mq-master02 ~]# cat /root/result.log
Wed Oct 10 20:35:27 CST 2018
192.168.10.13
It's so bad! main is failed!
--
192.168.10.16
It's so bad! main is failed! 

Wed Oct 10 20:35:29 CST 2018
192.168.10.13
It's so bad! main is failed!
--
192.168.10.16
It's so bad! main is failed! 

Wed Oct 10 20:35:29 CST 2018
192.168.10.13
It's so bad! main is failed!
--
192.168.10.16
It's so bad! main is failed! 

[root@mq-master02 ~]# echo -e "$(date +%Y年%m月%d日) $(date +%A) $(date +%H时%M分%S秒)\n$(echo "今天是个好日子啊") \n" > /root/result.log
You have new mail in /var/spool/mail/root
[root@mq-master02 ~]# echo -e "$(date +%Y年%m月%d日) $(date +%A) $(date +%H时%M分%S秒)\n$(echo "今天是个好日子啊") \n" >> /root/result.log
[root@mq-master02 ~]# echo -e "$(date +%Y年%m月%d日) $(date +%A) $(date +%H时%M分%S秒)\n$(echo "今天是个好日子啊") \n" >> /root/result.log
[root@mq-master02 ~]# cat /root/result.log
2018年10月10日 Wednesday 20时36分49秒
今天是个好日子啊 

2018年10月10日 Wednesday 20时36分52秒
今天是个好日子啊 

2018年10月10日 Wednesday 20时36分54秒
今天是个好日子啊 

ip列表文件
[root@kevin ~]# cat /opt/ip.list
192.168.10.11 
192.168.10.12   
192.168.10.13   
192.168.10.14 
192.168.10.15
192.168.10.16
192.168.10.17
 
 
main进程状态的检查脚本：
[root@kevin ~]# cat /opt/script/6_main_check.sh
#!/bin/bash
 
for i in $(cat /opt/ip.list)
do
/usr/bin/rsync -e "ssh -p22" -avpgolr /usr/bin/main_check $i:/usr/bin/ > /dev/null 2>&1
ssh -p22 root@$i "echo $i;sh /usr/bin/main_check"
done
 
[root@kevin ~]# cat /usr/bin/main_check
#!/bin/bash
NUM=$(ps -ef|grep -w main|grep -v grep|wc -l)
if [ $NUM -eq 0 ];then
   echo "Oh!My God! It's broken! main is stoped!"
else
   echo "Don't worry! main is running!"
fi
 
 
检查脚本执行结果
[root@kevin ~]# sh /opt/script/6_main_check.sh
192.168.10.11
Don't worry! main is running!
192.168.10.12
Don't worry! main is running!
192.168.10.13
Don't worry! main is running!
192.168.10.14
Don't worry! main is running!
192.168.10.15
Don't worry! main is running!
192.168.10.16
Don't worry! main is running!
192.168.10.17
Don't worry! main is running!
 
检查脚本执行结果的打印脚本
[root@kevin ~]# cat /mnt/main_check_result.sh
#!/bin/bash
NUM=$(/bin/bash /opt/script/6_main_check.sh |grep -w "main is stoped"|wc -l)
CONTENT=$(/bin/bash /opt/script/6_main_check.sh |grep -w "main is stoped")
if [ $NUM -ne 0 ];then
    echo -e "$(date +%Y年%m月%d日) $(date +%A) $(date +%H时%M分%S秒)\n$(/bin/bash /opt/script/6_main_check.sh |grep  "main is stoped" -B1)\n">> /mnt/main_check_result.log
else
    echo -e "$(date +%Y年%m月%d日) $(date +%A) $(date +%H时%M分%S秒)\n$(echo "当前时段所有机器的main进程运行正常,无需担心哈!")\n">> /mnt/main_check_result.log
fi
 
main检查的结果文件内容
[root@kevin ~]# cat /mnt/main_check_result.log
2018年10月10日 星期三 20时30分41秒
当前时段所有机器的main进程运行正常,无需担心哈!
 
2018年10月10日 Wednesday 20时30分46秒
当前时段所有机器的main进程运行正常,无需担心哈!
 
2018年10月10日 Wednesday 20时35分45秒
当前时段所有机器的main进程运行正常,无需担心哈!
 
2018年10月10日 Wednesday 20时40分45秒
当前时段所有机器的main进程运行正常,无需担心哈!

以上的脚本：不管main进程状态检查结果是否正常，都打印一个结果到/mnt/main_check_result.log文件中，
其实检查结果正常的时候，可以不必打印结果（即echo "****" > /dev/null 2 >&1）；
只有检查结果不正常的时候才打印结果，这样比较好点。

对/mnt/main_check_result.log文件大小做判断，当该文件大于60M(即61865984)时就清空。

[root@kevin ~]# ls -l /mnt/main_check_result.log
-rw-r--r--. 1 root root 16998 Nov 19  2017 /mnt/main_check_result.log

[root@kevin ~]# ls -l /mnt/main_check_result.log|awk '{print $5}'
16998

[root@kevin ~]# ls -l /mnt/main_check_result.log|awk '{print $9}'
/mnt/main_check_result.log

[root@kevin ~]# vim /root/main_check_result.log_del.sh
#!/bin/bash
size=$(ls -l /mnt/main_check_result.log|awk '{print $5}')
file=$(ls -l /mnt/main_check_result.log|awk '{print $9}')

if [ $size -gt 61865984 ] ; then 
    echo $file; echo $size
    echo >$file
fi

[root@kevin ~]# chmod 755 /root/main_check_result.log_del.sh
[root@kevin ~]# crontab -e
0 1 * * 6 /bin/bash -x /root/main_check_result.log_del.sh >/dev/null 2>&1