curl抓取http response header字符串拼接問題

我是想獲取header爲Connection的值。然後兩邊拼接單引號。於是直接使用普通的方法發生了字符串拼接不上。會發生覆蓋。
示例代碼1（原始方案）你會發現右邊單引號始終拼接不上去：
chengli.zou@clz-mbp Desktop % echo "'"$(curl -I https://www.baidu.com|grep Connection|awk '{print $2}')"'"
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0   277    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
'keep-alive

示例代碼2（原始方案放大）可以斷定是發生了覆蓋：
chengli.zou@clz-mbp Desktop % echo "'"$(curl -I https://www.baidu.com|grep Connection|awk '{print $2}')"hehe" 
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0   277    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
hehep-alive
chengli.zou@clz-mbp Desktop % 


示例代碼3（替代方案）：
chengli.zou@clz-mbp Desktop % cat curl-grep-token.sh 
#!/bin/bash
shopt -s extglob
function grepToken()
{
    while IFS=':' read key value; do
        value=${value##+([[:space:]])}; value=${value%%+([[:space:]])}
        case "$key" in
            Server) SERVER="$value"
                    ;;
            Connection) TOKEN="$value"
                    ;;
            HTTP*) read PROTO STATUS MSG <<< "$key{$value:+:$value}"
                    ;;
         esac
    done < <(curl -sI $1)
    echo $TOKEN
}
token=$(grepToken http://www.baidu.com)
echo "'"$token"'"
chengli.zou@clz-mbp Desktop % ./curl-grep-token.sh 
'keep-alive'