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Full Discussion: Question on pipes in C
Top Forums Programming Question on pipes in C Post 302512760 by omega666 on Monday 11th of April 2011 02:46:39 PM
Old 04-11-2011
Error Question on pipes in C

If a code forks 2 childs, what can the values be for the process id's of each of the child? I child pid is supposed to be 0, but what if you fork 2 of them?
 

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setpgid(2)							System Calls Manual							setpgid(2)

NAME
setpgid(), setpgrp2() - set process group ID for job control SYNOPSIS
DESCRIPTION
The and system calls cause the process specified by pid to join an existing process group or create a new process group within the session of the calling process. The process group ID of the process whose process ID is pid is set to pgid. If pid is zero, the process ID of the calling process is used. If pgid is zero, the process ID of the indicated process is used. The process group ID of a session leader does not change. is provided for backward compatibility only. Security Restrictions Some or all of the actions associated with this system call are subject to compartmental restrictions. See compartments(5) for more information about compartmentalization on systems that support that feature. Compartmental restrictions can be overridden if the process possesses the privilege (COMMALLOWED). Processes owned by the superuser may not have this privilege. Pro- cesses owned by any user may have this privilege, depending on system configuration. See privileges(5) for more information about privileged access on systems that support fine-grained privileges. RETURN VALUE
and return the following values: Successful completion. Failure. is set to indicate the error. ERRORS
If or fails, is set to one of the following values. The value of pid matches the process ID of a child process of the calling process and the child process has successfully executed one of the exec(2) functions. The value of pgid is less than zero or is outside the range of valid process group ID values. The process indicated by pid is a session leader. The value of pid is valid but matches the process ID of a child process of the calling process, and the child process is not in the same session as the calling process. The value of pgid does not match the process ID of the process indicated by pid and there is no process with a process group ID that matches the value of pgid in the same session as the calling process. The value of pid does not match the process ID of the calling process or of a child process of the calling process. AUTHOR
and were developed by HP and the University of California, Berkeley. SEE ALSO
bsdproc(3C), exec(2), exit(2), fork(2), getpid(2), kill(2), setsid(2), signal(2), privileges(5), termio(7). STANDARDS CONFORMANCE
setpgid(2)
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