向大家分享一个shell脚本的坑

打算在跳板机上写一个shell脚本，批量检查远程服务器上的main进程是否在健康运行中。

[root@two002 tmp]# ps -ef|grep main
root     23448 23422  0 11:40 pts/0    00:00:00 grep --color=auto main
 
[root@two002 tmp]# ps -ef|grep main|grep -v grep|wc -l
0

[root@two002 tmp]# cat /tmp/main_check.sh
#!/bin/bash
NUM=$(ps -ef|grep main|grep -v grep|wc -l)
if [ $NUM -eq 0 ];then
   echo "It's not good! main is stoped!"
else
   echo "Don't worry! main is running!"
fi

[root@two002 tmp]# sh -x /tmp/main_check.sh
++ grep main
++ grep -v grep
++ wc -l
++ ps -ef
+ NUM=2
+ '[' 2 -eq 0 ']'
+ echo 'Don'/''t worry! main is running!'
Don't worry! main is running!
 
[root@two002 tmp]# sh /tmp/main_check.sh
Don't worry! main is running!

如上执行结果，发现脚本执行过程中，看到赋予NUM参数的结果值是2！但是手动执行ps -ef|grep main|grep -v grep|wc -l的结果明明是0！！
这是由于grep匹配的问题，需要grep进行精准匹配，即”grep -w”。这就需要将main_check.sh脚本内容修改如下：

[root@two002 tmp]# cat /tmp/main_check.sh
#!/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

[root@two002 tmp]# sh -x /tmp/main_check.sh
++ grep -w main
++ grep -v grep
++ wc -l
++ ps -ef
+ NUM=0
+ '[' 0 -eq 0 ']'
+ echo 'Oh!My God! It'/''s broken! main is stoped!'
Oh!My God! It's broken! main is stoped!
 
[root@two002 tmp]# sh /tmp/main_check.sh
Oh!My God! It's broken! main is stoped!

[root@tiaoban ~]# 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
 
[root@tiaoban ~]# cat /opt/script/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