opensolaris man page for getsid

getsid(2)							   System Calls 							 getsid(2)

NAME
       getsid - get process group ID of session leader

SYNOPSIS
       #include <unistd.h>

       pid_t getsid(pid_t pid);

DESCRIPTION
       The  getsid()  function	obtains 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 VALUES
       Upon successful completion, getsid() returns the process group ID of the session leader of the specified  process.  Otherwise,  it  returns
       (pid_t)-1 and sets errno to indicate the error.

ERRORS
       The getsid() function will 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.

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

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+

SEE ALSO
       exec(2), fork(2), getpid(2), getpgid(2), setpgid(2), setsid(2), attributes(5), standards(5)

SunOS 5.11							    22 Jan 1996 							 getsid(2)