[info-mcl] MCL Contribution: Execute shell commands

[terje]

I have enclosed a new contribution to execute shell commands from  
MCL. For example, this will list the current directory:

(execute-shell-command "ls")

Importantly, using this contribution to execute shell commands DOES  
NOT BLOCK MCL during execution of the shell commands, thanks to the  
use of KQueue to get notified when new characters are available for  
input from the process. You may for example execute the following  
without hanging MCL:

(execute-shell-command "sleep 5")

Alternatively, provide an optional stream to write the output. Here  
is an example that writes the calendar of the current month typically  
to the Listener:

(execute-shell-command "cal" :output-stream *debug-io*)

There is also a stream for I/O from the BSD process executing the  
shell command. Hence you can write code like this:

(with-open-stream (ps (popen "cal"))
   (loop
      for c = (read-char ps nil)
      while c
      do (write-char c *debug-io*)))

Note that Popen requires the KQueue contribution I sent in the  
previous post.

-- Terje Norderhaug

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