查看JBoss进程

本语句实现首先检查JBoss进程，如果不存在则启动JBoss。

ps -ef |grep $USER > temp.txt && grep "java -server -Xms2G -Xmx2G" temp.txt && echo jboss is started || ($JBOSS_HOME/bin/run.sh && sleep 120)

 

解释：

1， 如果写成 ps -ef |grep $USER | grep "java -server -Xms2G -Xmx2G" && echo jboss is started || ($JBOSS_HOME/bin/run.sh && sleep 120) 将无法实现所需功能。

 

ps -ef |grep $USER | grep "java -server -Xms2G -Xmx2G" 永远返回 0，成功

ps -ef |grep $USER | grep "abcdefg" 同样永远返回 0，成功

 

2，($JBOSS_HOME/bin/run.sh && sleep 120)，这两个小括号不可省略。

 

3，&&

AND logical operator. In a test construct, the && operator causes a return of 0 (success) only if both the linked test conditions are true.

 

4，||

OR logical operator. In a test construct, the || operator causes a return of 0 (success) if either of the linked test conditions is true.