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Full Discussion: Doubt about pipes and subprocess
Top Forums Shell Programming and Scripting Doubt about pipes and subprocess Post 302388832 by Andre_Merzky on Thursday 21st of January 2010 02:58:15 PM
Old 01-21-2010
Hope this helps:

Code:
bash-3.2$ cat getppid.c 

#include <stdio.h>
#include <unistd.h>

int main ()
{
  fprintf (stdout, "%d\n", getppid ());
  return 0;
}

bash-3.2$ make getppid
cc     getppid.c   -o getppid

bash-3.2$ ./getppid >> t |  ( ./getppid >> t ; ./getppid >> t ) ; cat t
14236
14774
14774

I assume you talk about bash - tcsh is different here:

Code:
tcsh $  ( ./getppid ; ./getppid )
14867
12872

Last edited by Andre_Merzky; 01-21-2010 at 03:59 PM.. Reason: Who needs preview if you can edit ;-)
 

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LEARN ABOUT OPENSOLARIS

getppid

getpid(2)							   System Calls 							 getpid(2)

NAME

       getpid, getpgrp, getppid, getpgid - get process, process group, and parent process IDs

SYNOPSIS

       #include <unistd.h>

       pid_t getpid(void);

       pid_t getpgrp(void);

       pid_t getppid(void);

       pid_t getpgid(pid_t pid);

DESCRIPTION

       The getpid() function returns the process ID of the calling process.

       The getpgrp() function returns the process group ID of the calling process.

       The getppid() function returns the parent process ID of the calling process.

       The getpgid() function returns the process group ID of the process whose process ID is equal to pid, or the process group ID of the calling
       process, if pid is equal to 0.

RETURN VALUES

       The getpid(), getpgrp(), and getppid() functions are always successful and no return value is reserved to indicate an error.

       Upon successful completion, getpgid() returns the process group ID. Otherwise, getpgid() returns (pid_t)-1 and sets errno to  indicate  the
       error.

ERRORS

       The getpgid() function will fail if:

       EPERM	The  process  whose process  ID is equal to pid is not in the same session as the calling process, and the implementation does not
		allow access to the process group ID of that process from the calling process.

       ESRCH	There is no process with a process ID equal to pid.

       The getpgid() function may fail if:

       EINVAL	 The value of the pid argument is invalid.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Committed 		   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |Async-Signal-Safe 	   |
       +-----------------------------+-----------------------------+
       |Standard		     |See standards(5). 	   |
       +-----------------------------+-----------------------------+

SEE ALSO

       Intro(2), exec(2), fork(2), getsid(2), setpgid(2), setpgrp(2), setsid(2), signal(3C), attributes(5), standards(5)

SunOS 5.11							    27 Jan 2009 							 getpid(2)
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