Question

I’m in a Windows prompt, i.e. cmd.exe; “camlprog” does nothing but print its arguments (i.e. argv) separated by “\n” (i.e. each one on its own line).

First case:

c:\> c:\cygwin\bin\bash -c "c:/cygwin/home/jonathan/camlprog \"foo\" bar"
c:\cygwin\home\jonathan\camlprog.exe
foo bar

Second case:

c:\> c:\cygwin\bin\bash -c "~/camlprog \"foo\" bar"
c:\cygwin\home\jonathan\camlprog.exe
foo
bar

To me, the first case is definitely wrong: camlprog is being passed foo bar as its only argument instead of two separate foo and bar arguments. I imagined it would be equivalent to:

c:\> c:\cygwin\bin\bash
jonathan@host:$ c:/.../camlprog "foo" bar

which of course prints

foo
bar

Am I missing something? Does anyone have an idea what’s going on?

Thanks,

jonathan

Answer 1

This probably has to do with the way bash handle its parameters. Actually, we need to take a look on bash’s source code to assure what’s really happening, but you can be sure the reason for this strange behavior is there.

I made this conclusion based on the way Windows handles double quotes and slashes. Windows does not handle strings the same way Unix-like systems do. Shortly, there is no way to escape double-quotes inside double-quoted strings.

In order to ensure this, create a file named test.bat on Windows with this content:

@echo off
echo %1

And invoke it passing your parameter:

C:\> test.bat "c:/cygwin/home/jonathan/camlprog \"foo\" bar"

As result you will get:

"c:/cygwin/home/jonathan/camlprog \"foo\" bar"

Which means the slashes and all other characters are passed to script. So, in your case, they are being passed to bash, which is handling these characters for you, and it is doing this in some inconsistent way.

So, to workaround your problem, you can invoke your command this way:

 c:\> c:\cygwin\bin\bash -c 'c:/cygwin/home/jonathan/camlprog "foo" bar'
 foo
 bar

Using single quotes first and double quotes later, the script camlprog seems to run as expected.