if [[ $1 =~ $2 ]] 中 =~这个符号 和[[ ]] 两个中括号表示什么意思啊

zredkid

RT~谢谢~

ly5066113

man bash

luyi1983

用[[ ... ]]测试结构比用[ ... ]更能防止脚本里的许多逻辑错误。比如说，&&,||,<和>操作符能在一个[[]]测试里通过，但在[]结构会发生错误。

Shell_HAT

到ABS里面分别搜索[[和=~

Advanced Bash-Scripting Guide 3.9.1 中文版.pdf
http://bbs2.chinaunix.net/thread-1610033-1-1.html

dai_zi8211

[[]]==>Test expression between [[]]. More flexible than the singel-bracket[]test, this is shell keyword
[]==>Test exprression between[]. Note that [ is part of the shell builtin test(and a synonym for it), not a link to the external command /usr/bin/test