[Mingw-users] Piping problem when mixing UNIX-WINDOWS programs

[BGINFO4X <bgi...@kz...>]

Hello everybody,

I'm having a issue piping two programs: Program1 | Program2. I use MSYS
1.0.18.

Program2 is always the "convert" program from ImageMagick (the Windows
portable version).
Program1 "cats" a file to the pipe. I use two tests files: winfile (CRLF)
and unixfile (LF)


A) If I pipe the two programs INSIDE CMD, all the tests are always OK:

type winfile.txt | convert label:@- winfile.png
type unixfile.txt | convert label:@- unixfile.png

B) If I pipe the two programs INSIDE MSYS, exactlly equally as done in A),
all the tests are always OK:

$ cmd.exe /c "type winfile.txt" | cmd.exe /c "convert label:@- winfile.png"
$ cmd.exe /c "type unixfile.txt" | cmd.exe /c "convert label:@-
unixfile.png"


The problem starts when I mix /bin/cat (instead of type) with the convert
program. For example:

C) Mixing cat (unix program) with convert(Windows program) -> results OK

$ cat winfile.txt | cmd.exe /c "convert label:@- winfile.png"
$ cat unixfile.txt | cmd.exe /c "convert label:@- unixfile.png"

D) Mixing type (windows program) with convert (executed directly by
MSYS(not cmd.exe)) -> results OK
$ cmd.exe /c "type winfile.txt" | convert label:@- winfile.png
$ cmd.exe /c "type unixfile.txt" | convert label:@- unixfile.png

E) "Native MSYS" -> Mixing cat (unix program) with convert(executed
directly by MSYS)
$ cat winfile.txt | convert label:@- winfile.png
convert.exe: no images defined `winfile.png' @
error/convert.c/ConvertImageCommand/3068.
$ cat unixfile.txt | convert label:@- unixfile.png
convert.exe: no images defined `unixfile.png' @
error/convert.c/ConvertImageCommand/3068.

In Windows 2012, I get this error always (100% of the cases).
In Windows 7, I get this error sometimes (20% of the cases).

I opened a bug in Imagemagick, because I thought that it was related to
convert (it happens sometimes in Windows 7), but with little success. (
http://www.imagemagick.org/discourse-server/viewtopic.php?f=3&t=22781)
But yesterday, when I tried in a new Windows 2012, I checked that the
piping ALWAYS fails, so I started to thought that it was related to MSYS
(or not) and started to test the explained tests (A,B,C,D,E).

Now I have basically these questions:

1- Is it necessary to piping windows programs with cmd.exe /c "program"?
Case B)

2- Is it correct to pipe the programs as (case E) "Native MSYS": cat |
convert? I think that it is, but it fails.

3- Why the piping works if one of the two programs uses cmd.exe? case C) or
D)

4- Do you have some light of the problem?

I also checked in the mail list and found this post from Keith (it seems
related, but not 100% sure):
http://sourceforge.net/mailarchive/forum.php?thread_name=OFD6894437.E8412F0B-ON80256D9D.003B884D-80256D9D.0044EF54%40LocalDomain&forum_name=mingw-msys

Thanks a lot for your time.

Regards.