将 java -version 重定向到文件或变量

2022-01-23 00:00:00 command variables linux redirect java

也许这是一个愚蠢的问题，但我试图将java -version"命令的退出重定向到文件或变量，但它不起作用.

Maybe it is a silly question, but I'm trying to redirect the exit of "java -version" command to a file or variable but it doesn't work.

服务器 = Linux CentOS 6

Server = Linux CentOS 6

我在 shell 脚本中的代码

My code in shell script

java -version >> test.txt

我也在尝试将它分配给一个变量:

Also I'm trying to assign it to a variable:

JAVA_CHECK=`java -version`

即使从命令行运行这些命令，它仍然无法正常工作.

Even running those command from command-line it still not working.

当我说它不起作用时，我的意思是命令的退出显示在我的屏幕上，而不是将其重定向到文件或任何地方

when I say it doesnt work, I mean that the exit of the command is being showed in my screen instead to redirect it to a file or wherever

...

推荐答案

java -version 写入 stderr (fileno 2)，而不是 stdout (fileno 1).您可以将 stderr 重定向到文件:

java -version writes to stderr (fileno 2), not stdout (fileno 1). You can redirect stderr to a file:

java -version 2> test.txt
# cat test.txt 
# java version "1.7.0_25"
# OpenJDK Runtime Environment
# [...]

或者您可以将标准错误重定向到标准输出:

Or you can redirect stderr to stdout:

java_check=$(java -version 2>&1)
# echo "$java_check"
# java version "1.7.0_25" OpenJDK Runtime Environment [...]

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