Intro: linux package into the jar, the use of regular monitoring items and start crontab (crontab -e)
(Test: executed once every three minutes)
Qustion1.Exception in thread "main" java.lang.UnsupportedClassVersionError
Answer1. Compile in eclipse using java version "1.8.0_111", while the server version java version "1.8.0_066", incompatible cause problems. (I will be here in linux jdk replace 1.8.0_111)
step1: View linux version of Java java -version
step2: Uninstall
rm -rf JDK address (uninstall JDK) rm -rf /usr/java/jdk/jdk1.8.0_066/
step3: Download
wget http://download.oracle.com/otn-pub/java/jdk/8u171-b11/512cd62ec5174c3487ac17c61aaa89e8/jdk-8u171-linux-x64.tar.gz
step4: unzip
Execute: tar -zxvf jdk-8u171-linux-x64.tar.gz
Error: The following diagram
. Qustion2 use wget command to directly download the JDK, resulting in tar package can not command to extract
Answer2: to Oracle's official website downloaded jdk children's shoes should know, need to agree to the installation of Oracle agreement before downloading, otherwise it can not be downloaded, but with wget way, default do not agree, although able to download, but downloaded file there will be problems, so unzip on Linux has failed. (Article results from students https://www.cnblogs.com/shamo89/p/9265220.html )
step5: retest java -version
After connecting to the server again closed Xshell, the test is successful.
step6: Linux timed task starts jar
Qustion3：
Answer3: linux can not find the Java command, the more absolute path here
Qustion4： /var/spool/mail/root
View this message found as follows:
Answer4: linux lsof command can not be found, the more absolute path here (with the Java command)
