Manual Pages for UNIX Operating System command usage for man setsid

System Calls                                            setsid(2)



NAME
     setsid - create session and set process group ID

SYNOPSIS
     #include 
     #include 

     pid_t setsid(void);


DESCRIPTION
     The setsid() function creates a new session, if the  calling
     process  is not a process group leader. Upon return the cal-
     ling process will be the session leader of this new session,
     will be the process group leader of a new process group, and
     will have no controlling terminal. The process group  ID  of
     the  calling  process will be set equal to the process ID of
     the calling process. The calling process will  be  the  only
     process in the new process group and the only process in the
     new session.

RETURN VALUES
     Upon successful completion, setsid() returns  the  value  of
     the  process  group  ID of the calling process. Otherwise it
     returns (pid_t)-1 and sets errno to indicate the error.

ERRORS
     The setsid() function will fail if:

     EPERM    The calling process  is  already  a  process  group
              leader, or the process group  ID of a process other
              than the calling process matches the process  ID of
              the calling process.


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

















SunOS 5.11          Last change: 21 Aug 2002                    1






System Calls                                            setsid(2)



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


SEE ALSO
     getsid(2),  setpgid(2),  setpgrp(2),  attributes(5),   stan-
     dards(5)

WARNINGS
     A call to setsid() by a process  that  is  a  process  group
     leader  will  fail.  A  process  can  become a process group
     leader by being the last member of a pipeline started  by  a
     job  control  shell. Thus, a process that expects to be part
     of a pipeline, and that calls setsid(), should always  first
     fork;  the parent should exit and the child should call set-
     sid(). This will ensure that the calling process  will  work
     reliably when started by both job control shells and non-job
     control shells.






























SunOS 5.11          Last change: 21 Aug 2002                    2