When crontab scheduled task executes jar through script, it encounters a pit where jar package execution is invalid

         I wrote a simple one VPN The program , The requirement is to obtain the login user ip Address , Then by adding IPtables The rules , Achieve the release function , Everything's ready , meanwhile , By manually executing the script file , It is already possible to add rules .

        However, what I never thought of , For the convenience of future use , I choose to use crontab Scheduled tasks come , Every once in a while , Execute the script once . Everything was fine , Results after the deployment , I found the final result , It's different from what I expected , Because he ----- No implementation java Program ！！！

 

        what？？ I was stunned . It can be done manually , Why timing cannot be executed , It's so hard that I wrote the wrong code ？ But , Obviously, it can be implemented , Is it difficult that the script is not executed ？ But after adding other commands in the script , Discovery is executable , But when ordered , involves java The execution result of the file , Are unable to succeed . That is to say, the mistake is jar Implementation . After inspection ,java The code is correct , The execution path is also correct . I checked a lot of information on the Internet , then , Discovery execution jar Before the bag , You should first introduce environment variables ：

Before the introduction ：

java -jar /bbb/vpnTest.jar

After introducing environment variables ：

source /etc/profile

java -jar /bbb/vpnTest.jar

  And then execute , There is no problem .