Linux 在 Bash while 循环中使用“and”
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Using "and" in Bash while loop
提问by Smitty
Okay, essentially this is what the script looks like:
好的，基本上这就是脚本的样子：
echo -n "Guess my number: "
read guess
while [ $guess != 5 ]; do
echo Your answer is $guess. This is incorrect. Please try again.
echo -n "What is your guess? "
read guess
done
echo "That's correct! The answer was $guess!"
What I want to change is this line:
我想改变的是这一行：
while [ $guess != 5 ]; do
To something like this:
对于这样的事情：
while [ $guess != 5 and $guess != 10 ]; do
In Java I know "and" is " && " but that doesn't seem to work here. Am I going about this the right way using a while loop?
在 Java 中，我知道“and”是“&&”，但这在这里似乎不起作用。我使用while循环以正确的方式解决这个问题吗？
采纳答案by thiton
The []operator in bash is syntactic sugar for a call to test, which is documented in man test. "or" is expressed by an infix -o, but you need an "and":
[]bash 中的运算符是调用 的语法糖test，记录在man test. “或”由中缀表示-o，但您需要一个“和”：
while [ $guess != 5 -a $guess != 10 ]; do
回答by Matvey Aksenov
There are 2 correct and portable ways to achieve what you want.
Good old shellsyntax:
有 2 种正确且可移植的方法来实现您想要的。
好的旧shell语法：
while [ "$guess" != 5 ] && [ "$guess" != 10 ]; do
And bashsyntax (as you specify):
和bash语法（如您所指定）：
while [[ "$guess" != 5 && "$guess" != 10 ]]; do
回答by tripleee
The portable and robust way is to use a casestatement instead. If you are not used to it, it might take a few looks just to wrap your head around the syntax.
可移植和健壮的方法是使用case语句代替。如果您不习惯它，可能需要多看几眼才能了解语法。
while true; do
case $guess in 5 | 10) break ;; esac
echo Your answer is $guess. This is incorrect. Please try again.
echo -n "What is your guess? "
read guess # not $guess
done
I used while truebut you could in fact use the casestatement there directly. It gets hairy to read and maintain, though.
我使用过，while true但实际上您可以case直接在那里使用该语句。不过，阅读和维护起来会很麻烦。
while case $guess in 5 | 10) false;; *) true;; esac; do ...
