Re: Potential asterisk expansion bug in Windows Git Bash?

From: Jeff King <peff@peff.net>
Date: Aug 14, 2019, 12:10 UTC
Message-ID: <20190814121045.GA30302@sigill.intra.peff.net>
In-Reply-To: <CAO=KXnspgZa=R9=8wvPY-Y8pvuAah-D+Jc4CM_+cdemYGUJ09A@mail.gmail.com>

On Wed, Aug 14, 2019 at 07:50:47PM +0800, Bo Zhang wrote:

Show 19 quoted lines

> Today I noticed that on Windows Git Bash, the asterisk (*) is
> incorrectly expanded even when it’s in a quote or following a
> backslash (\). I’m wondering if this is the correct behaviour (which
> seems like to me NOT).
> 
> Step to reproduce (in Windows git bash):
> 
> zhb@zhb-PC MINGW64 ~/Desktop
> $ bash --version
> GNU bash, version 4.4.19(2)-release (x86_64-pc-msys)
> Copyright (C) 2016 Free Software Foundation, Inc.
> License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
> 
> This is free software; you are free to change and redistribute it.
> There is NO WARRANTY, to the extent permitted by law.
> 
> zhb@zhb-PC MINGW64 ~/Desktop
> $ cat 1.sh
> echo $1

Your script doesn't quote "$1", so whatever you pass in will be subject to wildcard expansion inside the shell running the script.

Try this:

  $ cat bad.sh
  echo $1
  $ cat good.sh
  echo "$1"

  $ bash bad.sh '*'
  bad.sh good.sh

  $ bash good.sh '*'
  *

> zhb@zhb-PC MINGW64 ~/Desktop
> $ bash 1.sh '*'
> $A 1.sh 1.txt

So this is the case I showed above.

> zhb@zhb-PC MINGW64 ~/Desktop
> $ bash 1.sh "*"
> $A 1.sh 1.txt

And this is equivalent. The quotes suppress wildcard expansion in your interactive shell, but the script itself does another round of expansion.

> zhb@zhb-PC MINGW64 ~/Desktop
> $ bash 1.sh \*
> 1.sh 1.txt

And same here.

-Peff