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Top Forums Shell Programming and Scripting Using System calls without compilation Post 302142567 by porter on Saturday 27th of October 2007 09:19:43 PM
Old 10-27-2007
Quote:
Originally Posted by yamsin789
My program need to call some system calls such as fork etc...
With a shell script using the "&" causes a fork without wait.

eg

Code:
#!/bin/sh

run_this_as_a_child()
{
     ps
}

echo parent is $$

run_this_as_a_child &

echo parent is $$, child was $!

wait

Perhaps Perl may be more what you want.
 

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FORK(2) 							System Calls Manual							   FORK(2)

NAME
fork - spawn new process SYNOPSIS
fork( ) DESCRIPTION
Fork is the only way new processes are created. The new process's core image is a copy of that of the caller of fork. The only distinc- tion is the fact that the value returned in the old (parent) process contains the process ID of the new (child) process, while the value returned in the child is 0. Process ID's range from 1 to 30,000. This process ID is used by wait(2). Files open before the fork are shared, and have a common read-write pointer. In particular, this is the way that standard input and output files are passed and also how pipes are set up. SEE ALSO
wait(2), exec(2) DIAGNOSTICS
Returns -1 and fails to create a process if: there is inadequate swap space, the user is not super-user and has too many processes, or the system's process table is full. Only the super-user can take the last process-table slot. ASSEMBLER
(fork = 2.) sys fork (new process return) (old process return, new process ID in r0) The return locations in the old and new process differ by one word. The C-bit is set in the old process if a new process could not be cre- ated. FORK(2)
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