检查 Java 是否与 Bash 一起安装
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/36388348/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Check if Java Installed with Bash
提问by WASasquatch
Can someone tell me why this simple command cannot find the output "java version"?
有人能告诉我为什么这个简单的命令找不到输出“java 版本”吗？
if java -version | grep -q "java version" ; then
echo "Java installed."
else
echo "Java NOT installed!"
fi
output from java -versionis as follows
输出java -version如下
java version "1.8.0_77"
Java(TM) SE Runtime Environment (build 1.8.0_77-b03)
Java HotSpot(TM) 64-Bit Server VM (build 25.77-b03, mixed mode)
回答by Reimeus
javaoutputs to STDERR. You can use
java输出到 STDERR。您可以使用
if java -version 2>&1 >/dev/null | grep -q "java version" ; then
but probably simpler to do something like
但可能更简单地做类似的事情
if [ -n `which java` ]; then
回答by chitresh
If your java is openJDK then you can use following options
如果您的 java 是 openJDK，那么您可以使用以下选项
java -version 2>&1 >/dev/null | grep "java version\|openjdk version"
or you can make more generic by
或者你可以通过
java -version 2>&1 >/dev/null | egrep "\S+\s+version"
to get java version
获取java版本
JAVA_VER=$(java -version 2>&1 >/dev/null | egrep "\S+\s+version" | awk '{print }' | tr -d '"')
