語法錯誤=〜運營商msysgit慶典

Question

我想要的功能添加到我的bash_profile爲msysgit：

function git-unpushed { 
    brinfo=$(git branch -v | grep git-branch-name) 
    if [[ $brinfo =~ ("[ahead "([[:digit:]]*)]) ]] 
    then 
     echo "(${BASH_REMATCH[2]})" 
    fi 
} 

，但我得到了以下錯誤：

bash: conditional binary operator expected`

bash: syntax error near =~'

從什麼我可以發現，「等於波浪號」運算符（=~）在bash中評估爲正則表達式。

爲什麼=~會引發錯誤？

更新：這是手動輸入它的截圖（這是運行sh.exe）：

Answer 1

更新2015年：msysgit現在已經過時。
你應該使用自帶的bash git-for-windows。
正如this answer中所述，它使用更近的bash（4.3+），其中=~語法將工作。

---

原來的答覆（2013年3月）

與msysgit包裝bash的可能僅僅是太老了，完全支持這種操作。
這當然是太舊與不帶引號的正則表達式進行比較，如 「Bash, version 3」 和 「How do I use regular expressions in bash scripts?」 中提到：其實

As of version 3.2 of Bash, expression to match no longer quoted.

，mklement0提到的評論：

=~ was introduced in bash 3.0 and always supported an unquoted token on the RHS.
Up to 3.1.x, quoted tokens were treated the same as unquoted tokens: both were interpreted as regexes.
What changed in 3.2 was that quoted tokens (or quoted substrings of a token) are now treated as literals.

但我試過用引號（在最新的msysgit 1.8.1.2中），它仍然失敗：

vonc@voncvb/
$ /bin/bash --version 
GNU bash, version 3.1.0(1)-release (i686-pc-msys) 
Copyright (C) 2005 Free Software Foundation, Inc. 
vonc@voncvb/
$ variable="This is a fine mess." 
vonc@voncvb/
$ echo "$variable" 
This is a fine mess. 
vonc@voncvb/
$ if [[ "$variable" =~ T.........fin*es* ]] ; then echo "ok" ; fi 
bash: conditional binary operator expected 
bash: syntax error near `=~' 
vonc@voncvb/
$ if [[ "$variable" =~ "T.........fin*es*" ]] ; then echo "ok" ; fi 
bash: conditional binary operator expected 
bash: syntax error near `=~' 
vonc@voncvb/

Answer 2

我在Bash 3.1.0上從Git安裝在Windows上有同樣的錯誤。最終，我把它改爲：

if echo $var | grep -E 'regexp' > /dev/null 
then 
    ... 
fi 

Answer 3

根據https://groups.google.com/forum/#!topic/msysgit/yPh85MPDyfE這是因爲MSYS不使用bash沿船長libregex。據說如果你編譯/找到一個msys構建libregex，並把它放在庫路徑中，=~開始工作正常。

Answer 4

這是一個支持提取匹配字符串的解決方案。如果運營商=〜不bash的支持，則使用sed命令（安裝了msysgit）

if eval "[[ a =~ a ]]" 2>/dev/null; then 
    regexMatch() { # (string, regex) 
     eval "[[ \$1 =~ \$2 ]]" 
     return $? 
    } 
elif command -v /bin/sed >/dev/null 2>&1; then 
    regexMatch() { # (string, regex) 
     local string=$1 
     if [[ ${2: -1} = $ ]]; then 
      local regex="(${2%$})()()()()()()()()$" 
     else 
      local regex="($2)()()()()()()()().*" 
     fi 
     regex=${regex//\//\\/} 
     local replacement="\1\n\2\n\3\n\4\n\5\n\6\n\7\n\8\n\9\n" 
     local OLD_IFS=$IFS 
     IFS=$'\n' 
     BASH_REMATCH=($(echo "$string" | /bin/sed -rn "s/$regex/$replacement/p" | while read -r; do echo "${REPLY}"; done)) 
     IFS=$OLD_IFS 
     [[ $BASH_REMATCH ]] && return 0 || return 1 
    } 
else 
    error "your Bash shell does not support regular expressions" 
fi 

用例：

if regexMatch "username@host.domain" "(.+)@(.+)"; then 
    echo ${BASH_REMATCH[0]} 
    echo ${BASH_REMATCH[1]} 
    echo ${BASH_REMATCH[2]} 
fi