Bash regex matching not working [duplicate]

问题

This question already has answers here:

Bash Regular Expression — Can't seem to match any of \s \S \d \D \w \W etc (5 answers)

Closed last year.

so I have this function

function test(){
 local output="CMD[hahahhaa]"
 if [[ "$output" =~ "/CMD\[.*?\]/" ]]; then
  echo "LOOL"
 else
  echo "$output"
 fi;

}

however executing test in command line would output $output instead of "LOOL" despite the fact that the pattern should be matching $output...

what did I do wrong?

回答1:

Don't use quotes ""

if [[ "$output" =~ ^CMD\[.*?\]$ ]]; then

---

Update : (in response to @frhd)

Well, the regex operator =~ expects an unquoted regular expression on its RHS and does only a sub-string match unless the anchors ^ (start of input) and $ (end of input) are also used to make it match the whole of the LHS.

Quotations "" override this behaviour and force a simple string match instead i.e. the matcher starts looking for all these characters \[.*?\] literally.

来源：https://stackoverflow.com/questions/19327220/bash-regex-matching-not-working