Bash中不区分大小写的比较 [英] Case insensitive comparison in Bash

问题描述

我正在尝试在不区分大小写的while语句中编写比较.基本上，我只是想简化以下内容，以便对用户显示是或否的问题提示...

I'm trying to write a comparison in a while statement that's case insensitive. Basically, I'm simply trying to shorten the following to act on a yes or no question prompt to the user ...

while[ $yn == "y" | $yn == "Y" | $yn == "Yes" | $yn == "yes" ] ; do

解决这个问题的最佳方法是什么?

What would be the best way to go about this?

推荐答案

shopt -s nocasematch
while [[ $yn == y || $yn == "yes" ]] ; do

或:

shopt -s nocasematch
while [[ $yn =~ (y|yes) ]] ; do

注意

• [[是bash关键字，与[命令类似(但功能更强大).参见 http://mywiki.wooledge.org/BashFAQ/031 和

  Note

  • [[ is a bash keyword similar to (but more powerful than) the [ command. See http://mywiki.wooledge.org/BashFAQ/031 and http://mywiki.wooledge.org/BashGuide/TestsAndConditionals
    Unless you're writing for POSIX sh, we recommend [[.
  • The =~ operator of [[ evaluates the left hand string against the right hand extended regular expression (ERE). After a successful match, BASH_REMATCH can be used to expand matched groups from the pattern. Quoted parts of the regex become literal. To be safe & compatible, put the regex in a parameter and do [[ $string =~ $regex ]]

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