Syntax error =~ operator in msysgit bash

问题

I'm trying to add a function to my bash_profile for msysgit:

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

But I get the following error:

bash: conditional binary operator expected`

bash: syntax error near =~'

From what I can find, the "equals tilde" operator (=~) evaluates as regex in bash.

Why is =~ is throwing an error?

UPDATE: Here's a screenshot of inputting it manually (this is running sh.exe):

回答1:

Update 2015: msysgit is now obsolete.
You should use the bash which comes with git-for-windows.
As mentioned in this answer, it uses a much more recent bash (4.3+), for which the =~ syntax will work.

Original answer (march 2013)

The bash packaged with msysgit might simply be too old to fully support this operator.
It is certainly too old ~~to compare with unquoted regex~~, as mentioned in "Bash, version 3" and "How do I use regular expressions in bash scripts?":

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

Actually, mklement0 mentions in the comments:

=~ 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.

But I tried with quotes (in the latest msysgit 1.8.1.2), and it still fails:

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 /

回答2:

I had the same error on Bash 3.1.0 from Git installation on Windows. Ultimately I changed it to:

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

回答3:

According to https://groups.google.com/forum/#!topic/msysgit/yPh85MPDyfE this is because msys doesn't ship libregex along with bash. Supposedly if you compile/find an msys built libregex, and put it in the library path, =~ starts working fine.

回答4:

Here is a solution that supports extracting matched strings. If the operator =~ is not supported by bash, then the sed command is used (installed with 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

Usage example:

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

来源：https://stackoverflow.com/questions/15510083/syntax-error-operator-in-msysgit-bash

标签

windows

bash

msysgit