Stdout and Shell commands

Mark Smith mark at
Mon Dec 4 23:05:59 EST 2006

Thanks, Dar. I might play around with "process", but it sounds like  
the file route is the way to go for now.



On 4 Dec 2006, at 22:52, Dar Scott wrote:

> On Dec 4, 2006, at 5:24 AM, Mark Smith wrote:
>> There are some shell commands (openssl sha1, for example) that  
>> take their arguments from stdin or a file, but not the command  
>> line. While it's easy to write data to a file and pass the  
>> filepath to the shell, it's not very efficient if you want to do  
>> it many times in succession.
> What you want is process i/o.  See 'open process' etc.
> There are some problems.  You have to do a half-close.  That is,  
> you need to close the pipe to the tool without closing the pipe  
> from the tool.
> Revolution tries to do a half-close with a a control character (04,  
> EOT, Control-D), but that doesn't work well.
> On OS X you cannot do a half-close with binary.  This was done to  
> fix a concern (bz 1770).
> On OS X this does do a half-close with text mode, but there seems  
> to be something fishy with the line ends in text mode.  Anybody  
> know what is wrong with the line ends in this case?  This needs a  
> bz but I'm not sure what is up.  I've tried this with sort and  
> things don't get sorted.
> On XP it gets a little mixed up with ^X or ^Z, I forgot which.   
> That is, Rev thinks it closed the pipe for ^D, but the application  
> thinks it is still open.  Maybe you can send ^X^Z^D and something  
> will happen.  I have some notes someplace but I don't think they  
> were enough to bugzilla.
> As you can see, I'm not clear on this.  We do need a half close  
> command for open process and open socket.
> If the tool reads a fixed number of lines or characters, you might  
> be OK.  You don't have to do the half close.
> I do have some other bugs reported on process I/O and some bugs  
> that are not ready for bz on process I/O.
> I'd go with the file for the input with shell() for now.  If the  
> output is binary, then you should use a file for output, too, on  
> Windows.  I have not had a problem with binary output on OS X.
> Note that passwords are often not input with stdin even though they  
> look like it.
> Dar
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