linux man page for getsid

GETSID(P)						     POSIX Programmer's Manual							 GETSID(P)

NAME
       getsid - get the process group ID of a session leader

SYNOPSIS
       #include <unistd.h>

       pid_t getsid(pid_t pid);

DESCRIPTION
       The  getsid()  function shall obtain the process group ID of the process that is the session leader of the process specified by pid. If pid
       is (pid_t)0, it specifies the calling process.

RETURN VALUE
       Upon successful completion, getsid() shall return the process group ID of the session leader of the specified process.  Otherwise, it shall
       return (pid_t)-1 and set errno to indicate the error.

ERRORS
       The getsid() function shall fail if:

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

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

       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       None.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       exec() , fork() , getpid() , getpgid() , setpgid() , setsid() , the Base Definitions volume of IEEE Std 1003.1-2001, <unistd.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
       ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
       Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and  the  original  IEEE
       and  The  Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained
       online at http://www.opengroup.org/unix/online.html .

IEEE
/The Open Group						       2003								 GETSID(P)