setsid(2)                  DG/UX 4.30                   setsid(2)



     NAME
          setsid - Create session and set process group ID.

     SYNOPSIS
          #include <sys/types.h>

          pid_t setsid ( )

     DESCRIPTION
          If the calling process is not a process group leader, the
          setsid() function shall create a new session.  The calling
          process shall be the session leader of this new session,
          shall be the process group leader of a new process group,
          and shall have no controlling terminal.  The process group
          ID of the calling process shall be set equal to the process
          ID of the calling process.  The calling process shall be the
          only process in the new process group and the only process
          in the new session.

     RETURNS
          Upon successful completion, the setsid() function returns
          the value of the process group ID of the calling process.

     ERRORS
          If any of the following conditions occur, the setsid()
          function shall return -1 and set errno to the corresponding
          value:

          [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.

     SEE ALSO
          exec(2), _exit(2), fork(2), getpid(2), kill(2) setpgid(2),
          sigaction(2)

     COPYRIGHTS
          Portions of this text are reprinted from IEEE Std 1003.1-
          1988, Portable Operating System Interface for Computer
          Environment, copyright © 1988 by the Institute of Electrical
          and Electronics Engineers, Inc., with the permission of the
          IEEE Standards Department.  To purchase IEEE Standards, call
          800/678-IEEE.

          In the event of a discrepancy between the electronic and the
          original printed version, the original version takes
          precedence.

     STANDARDS
          The only way for a session to allocate a controlling



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     setsid(2)                  DG/UX 4.30                   setsid(2)



          terminal is for the session leader (which must not already
          have a controlling terminal) to open a terminal device that
          is not already associated with any session, without using
          the O_NOCTTY option to open().  The effect is that the
          processes in a session may have at most one controlling
          terminal, and a terminal may have at most one controlling
          process, which must be a session leader.  When the
          controlling process terminates, an automatic vhangup()
          occurs on the terminal and its terminal characteristics are
          reset.













































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