shell脚本的坑:grep匹配+wc取值 在脚本执行后的结果与手动执行结果不一致

谁说胖子不能爱 提交于 2020-01-16 09:27:32

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。

先找出其中一台远程机器,查看main进程运行情况

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[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

shell检查脚本如下

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[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

执行脚本

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[root@two002 tmp]# sh -x /tmp/main_check.sh

++ grep main

++ grep -v grep

++ wc -l

++ ps -ef

+ NUM=2

'[' 2 -eq ']'

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

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[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

再次执行检查脚本,就OK了

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[root@two002 tmp]# sh -x /tmp/main_check.sh

++ grep -w main

++ grep -v grep

++ wc -l

++ ps -ef

+ NUM=0

'[' 0 -eq ']'

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!

故在跳板机上,批量检查远程服务器的main进程运行状态的脚本为:

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[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 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  

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