通过外壳传递以空格分隔的系统属性 [英] Passing a space-separated System Property via a shell

问题描述

我很难从使用嵌套变量的shell脚本（bash）启动Java程序。基本上，有许多系统和-D Java属性需要传递给Java程序。我想将它们更好地组织起来，因为它们在一行中很难阅读。

I'm having difficulties to startup a java program from a shell script (bash) where nested variables are used. Basically there are many system and -D java properties that need to be passed to a java program. I would like to organise them in a nicer way one below another as they are very difficult to read when in one line.

这类似于
< a href = https://stackoverflow.com/questions/8214392/passing-a-space-separated-system-property-via-a-shell-script-doesnt-work>通过传递空间分隔的系统属性shell脚本不起作用，但不一样。

这里是精简示例。想象这样的Java程序：

Here is a stripped down sample. Imagine a java program like this:

public class Main {
    public static void main(String[] args) {
        for (String s : args) {
            System.out.println(s);
        }
    }
}

当这样调用时：

java Main First_Line第二行带有空格

它将给出如下所示的OK结果：

It will give OK result like this response:

First_Line
Second line with spaces

但是是否使用了这样的脚本：

However if script like this is used:

#!/bin/sh
PARAM01="FirstLine"
PARAM02="Second line with spaces"
PARAMS="$PARAM01 $PARAM02"
java Main $PARAMS

然后全部空格被占用，第二个参数未加引号传递给java。结果如下所示：

Then all spaces are eaten and second parameter is passed unquoted to java. Result looks like this:

FirstLine
Second
line
with
spaces

试图用不同的方式引用变量在shell脚本中，但到目前为止没有成功。

Have tried to differently quote variables in a shell script, but so far without success. How to quote shell variables so that spaces are preserved and parameter is passed intact to java?

推荐答案

如果在shell变量上加引号，则如何引用shell变量，以便保留空格并将参数完整地传递给java？命令行 unquoted ，然后进行分词。为了防止单词分裂，请将每个参数都放在双引号中：

If you put a shell variable on the command line unquoted, then it undergoes word splitting. To prevent that word splitting, keep each parameter in double-quotes:

java Main "$PARAM01" "$PARAM02"

或者，如果您想花哨的话，请使用数组：

Or, if you want to get fancy, use an array:

PARAMS=("$PARAM01" "$PARAM02")
java Main "${PARAMS[@]}"

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