getpgrp(2)                                             getpgrp(2)



NAME
     getpgrp, setpgrp, getpgid - get/set process group

SYNOPSIS (SYSV)
     #include <sys/types.h>

     pid_t getpgrp ()

     pid_t setpgrp ()

SYNOPSIS (BSD)
     #include <sys/types.h>

     pid_t getpgrp (pid)
     pid_t pid;

     pid_t setpgrp (pid, pgrp)
     pid_t pid, pgrp;

SYNOPSIS
     pid_t getpgid (pid)
     pid_t pid;

DESCRIPTION
     These services get and set the process group ID of a pro-
     cess.

     In the att universe they apply to the calling process only.
     getpgrp returns the process group ID of the caller.  Setpgrp
     sets the process group ID of the caller to his process ID
     and returns the new process group ID.  It also has the side
     effect of relinquishing the controlling terminal, creating a
     new session and making the calling process the session
     leader.  See setsid (2).

     In the ucb universe they apply to process pid, with a pid of
     zero refering to the caller.  getpgrp returns the process
     group ID of the specified process.  Setpgrp sets the process
     group ID of the specified process to the value in pgrp.
     Setpgrp adheres to the POSIX rules regarding the setting of
     process groups.  See setpgid (2).

     Getpgid is equivalent to the ucb universe flavor of getpgrp,
     but is available from either universe.

     Process groups are used for distribution of signals, and by
     terminals to arbitrate requests for their input: processes
     which have the same process group as the terminal are fore-
     ground and may read, while others will block with a signal
     if they attempt to read.





Page 1                        CX/UX Programmer's Reference Manual

getpgrp(2)                                             getpgrp(2)



     This call is thus used by programs such as csh(1) to create
     process groups in implementing job control.  The TIOCGPGRP
     and TIOCSPGRP calls described in sgtty(7) are used to
     get/set the process group of the control terminal, as are
     the TC_PX_GETPGRP and TC_PX_SETPGRP calls described in ter-
     mios(7).

RETURN VALUE
     If an error occurs, the value -1 is returned, and a more
     precise error code is placed in the global variable errno.
     If the call succeeds, then getpgrp and getpgid return the
     process group ID, setpgrp in the att universe returns the
     new process group ID, and setpgrp in the ucb universe
     returns 0.

ERRORS
     getpgrp and getpgid will fail if one of the following occur:

     [ESRCH]        The value of the pid argument does not match
                    the process ID of the calling process or of a
                    child process of the calling process.

     Setpgrp will fail and the process group will not be altered
     if one of the following occur:

     [EACCES]       The value of the pid argument matches the
                    process ID of a child process of the calling
                    process and the child process has success-
                    fully executed one of the exec() functions.

     [EINVAL]       The value of the pgid argument is less than
                    zero or is not a value supported by the
                    implementation.

     [EPERM]        The process indicated by the pid argument is
                    a session leader.

                    The value of the pid argument 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 pro-
                    cess.

                    The value of the pgid argument does not match
                    the process ID of the process indicated by
                    the pid argument and there is no process with
                    a process group ID that matches the value of
                    the pgid argument in the same session as the
                    calling process.

     [ESRCH]        The value of the pid argument does not match
                    the process ID of the calling process or of a



Page 2                        CX/UX Programmer's Reference Manual

getpgrp(2)                                             getpgrp(2)



                    child process of the calling process.

SEE ALSO
     exec(2), fork(2), getpid(2), getuid(2), intro(2), kill(2),
     setpgid(2), setsid(2), signal(2), termio(7), termios(7).


















































Page 3                        CX/UX Programmer's Reference Manual