击：测试多个变量的相互平等？ [英] Bash: test mutual equality of multiple variables?

问题描述

什么是测试如果几个变量是正确的方式人人平等？

What is the right way to test if several variables are all equal?

if [[ $var1 = $var2 = $var3 ]] # syntax error

是否有必要写类似下面？

Is it necessary to write something like the following?

if [[ $var1 = $var2 && $var1 = $var3 && $var2 = $var3 ]] # cumbersome
if [[ $var1 = $var2 && $var2 = $var3 && $var3 = $var4 ]] # somewhat better

不幸的是，另有优秀高级bash脚本编程指南和其他在线资源，我能找到唐'吨提供这样的例子。

Unfortunately, the otherwise excellent Advanced Bash Scripting Guide and other online sources I could find don't provide such an example.

我的具体动机是，以测试几个目录都具有相同数量的文件使用 LS -1 $目录|厕所-l 计数的文件。

My particular motivation is to test if several directories all have the same number of files, using ls -1 $dir | wc -l to count files.

注意
结果
VAR1等都是例子变数。我在寻找任意变量名的解决方案，而不仅仅是那些有predictable数字的结局。

Note
"var1" etc. are example variables. I'm looking for a solution for arbitrary variable names, not just those with a predictable numeric ending.

更新
结果
我已经接受RICHO的回答，因为这是最普遍的。不过，我实际使用凯尔的，因为它是最简单的，我的投入有保证，避免警告。

Update
I've accepted Richo's answer, as it is the most general. However, I'm actually using Kyle's because it's the simplest and my inputs are guaranteed to avoid the caveat.

感谢您的建议，每个人。​​

Thanks for the suggestions, everyone.

推荐答案

如果你想测试项目任意数量的平等（我们称他们为$ item1-5，但他们可能是一个数组

if you want to test equality of an arbitrary number of items (let's call them $item1-5, but they could be an array

st=0
for i in $item2 $item3 $item4 $item5; do
    [ "$item1" = "$i" ]
    st=$(( $? + st ))
done

if [ $st -eq 0 ]; then
    echo "They were all the same"
fi

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