regex - shell脚本中 "=~"运算符的含义

Question

我遇到了一个shell脚本，代码是

for line in $LIST_ARRAY;do
if [[ $LIST_ARRAY =~ $line ]]
then
echo "true"
....
...
.

这种情况下=~有什么用？

Answer 1

这是允许在 if 语句中使用正则表达式的 Equal Tilde 运算符。

An additional binary operator, =~, is available, with the same precedence as == and !=. When it is used, the string to the right of the operator is considered an extended regular expression and matched accordingly (as in regex(3)). The return value is 0 if the string matches the pattern, and 1 otherwise. If the regular expression is syntactically incorrect, the conditional expression's return value is 2. If the shell option nocasematch is enabled, the match is performed without regard to the case of alphabetic characters. Any part of the pattern may be quoted to force it to be matched as a string.

http://linux.die.net/man/1/bash