Name: spoon - execute a parallel SLI-proce

Synopsis:

Command spoon -&gt; Child_PID      %for parent process 
-&gt; quit Command   %for child  process


Examples:

{ (I am the child!) = } spoon (I am the parent!) = 
Try this several times. You will notice the child message to appear 
before or after the parent message "by chance". (Even after the parent's 
I-prompt...)


Description:

Basic process management: execute a parallel SLI-process


Parameters:

In:  Command (any): (However, Command is most likely to be a literal 
procedure...) 
Command will be executed by the child process, 
which will terminate after execution. 
It will be ignored by the parent process. 
Out: For parent process: Child_PID (integer): The child's process-ID. 
For child  process: none.


Bugs:




Remarks:

A parallel process is forked. 
Parent and child will execute in parallel. There is no way to know which 
will start being executed first. 
Child inherits all open files, including stdin and stdout, from parent! 
If a SLI error is raised inside the child process, an error 
message is issued and the process is terminated, in oder not 
to leave two interactive SLI processes waiting for user 
input. A copy of the error message is printed to cerr, in 
case the standrad message stream M_OUT is redirected to a 
pipe (i.e. by the spawn command). 
Procedure: Call fork. 
Check if you are parent/child by test of (PID eq 0). 
If parent: discard (pop) Command, leave: (child)PID. 
If child : discard (pop) 0-PID, execute Command, quit.


Author:

R Kupper


FirstVersion:

Mar 18 1999


SeeAlso:

fork

Source:

/var/www/debian/nest/nest-simulator-2.20.0/lib/sli/processes.sli
