在Linux中如何检查脚本安装了哪个Java版本？

Question

alternate --config is updated

java -version works

How do i verify if java is installed if java is installed and what version. What is the correct way.

Answer 1

I think this is what you want:

#!/bin/bash
if [ -x /usr/bin/java ] ; then
        java -version 2>&1 | head -1 | awk -F '"' '{print $2}'
else
        exit
fi

OUTPUT (on my linux box):

1.6.0_18

check whether the java executable is present. if yes, then print the version.

Answer 2

I hope the following code may help you, please try it,

a=`(java -version) 2>&1`
if [[ "$a" == *1.7* ]]
then 
    echo '1.7'
fi 

Answer 3

Depends on how you expect it to be installed; there are two ways to find the java binary:

• look for java in PATH (which is what you're doing by executing java -version )
• if JAVA_HOME is defined, treat that as the preferred installation and run $JAVA_HOME/bin/java -version

After that, just extract the version number from the output as you need (see slayedbylucifer's answer above).