R devel - Nov 2003 - problem with pipes (PR#5053)

Full_Name: Gabor Grothendieck
Version: 1.8.0
OS: Windows 2000 Pro
Submission from: (NULL) (67.68.47.99)



In R 1.8.0 on Windows 2000 suppose that \a.bat contains the following two
lines:

net /? 
dir \winnt

which constitutes a simple batch file which 
1. writes a help message about the built in Windows net command to stderr and 
2. does a dir on the built in Windows directory WINNT writing result to stdout

You can replace #1 with any other command which outputs to stderr and #2 with
any other command that outputs to stdout.  I just chose those commands since
they come with Windows.

If you start up R and run a pipe which executes \a.bat one gets
the following werid behavior on Windows 2000:
> readLines(pipe("\\a.bat"))
 [1] ""
 [2] "C:\\Program Files\\R\\rw1080>net /? "
 [3] "The syntax of this command is:"
 [4] ""
 [5] ""
 [6] ""
 [7] ""
 [8] "NET [ ACCOUNTS | COMPUTER | CONFIG | CONTINUE | FILE | GROUP | HELP
|"
 [9] "      HELPMSG | LOCALGROUP | NAME | PAUSE | PRINT | SEND | SESSION
|"
[10] "      SHARE | START | STATISTICS | STOP | TIME | USE | USER | VIEW
]"
[11] ""
[12] ""
[13] "C:\\Program Files\\R\\rw1080>dir \\a.bat "
[14] " Volume in drive C has no label."
[15] " Volume Serial Number is 07D1-011A"
[16] ""
[17] " Directory of C:\\"
[18] ""
[19] "11/12/2003  05:07p                  20 a.bat"
[20] "               1 File(s)             20 bytes"
[21] "               0 Dir(s)     484,712,448 bytes free"  


There are several problems:

1. I am getting both the stderr (the output from net /?) and the stdout
   (the output from dir).

2. The first line contains a weird character.  This character changes if
I perform the R command multiple times.

3. Usually I get the above but sometimes I get no output from readLines at
all.

I found this when I was trying to pipe output from a command (not the above
batch file which is just an simpler example) to R and finally traced it the 
above.

The above is sufficiently serious that I can't use pipes in R currently
on Windows 2000.

I am using R 1.8.0 but R 1.7.1 gives the same.

I had previously posted a version of this to r-help just to verify whether it
was a bug or not but no one answered so I guess it is.  My r-help message
used gawk instead of a batch file to illustrate this behavior.  See:

https://www.stat.math.ethz.ch/pipermail/r-help/2003-November/040426.html

On Wed, 12 Nov 2003 ggrothendieck@myway.com wrote:
>
> 3. Usually I get the above but sometimes I get no output from readLines at
> all.
>
This last problem may be the same as PR#1140 on the Mac, where popen()
calls sometimes got killed by an interrupt.

	-thomas

I am assuming this is related to the bug report I previously
submitted; however, this time I am getting different behavior
so I thought it might be helpful just in case this gives a clue.

On Windows 2000 the following code crashes R:
> z <- readLines(con <- pipe("cmd /c attrib c:/a*.txt"))
> z
[1] "¬A          C:\\addr.txt~" "A          C:\\a.awk.txt" 
[3] "A          C:\\a.txt~"    
> close(con)
It crashes when I issue the close command.  What happens specifically
is that a window pops up saying "Rgui has generated errors and
with be closed by windows".    R then shuts down.

I am using Windows 2000 and R 1.8.1.