setpgid(2)                                                   setpgid(2)

  setpgid()

  NAME

    setpgid() - set process group

  SYNOPSIS

    #include 

    int setpgid (pid_t pid, pid_t pgrp)

  DESCRIPTION

    The setpgid(2) function is used either to join an existing process group
    or to create a new process group within the session of the calling
    process. A new process group is created if and only if pid and pgrp denote
    the same process, and no errors occur.

    Upon successful completion, the process group ID of the process specified
    by pid is set to pgrp.

    If pid is zero, the process ID of the current process is used. If pgrp is
    zero, the process ID of the indicated group is used. This creates a new
    group, if the group doesn't already exist.

    The setpgid(2) call will not fail if the indicated process or the leader
    of the indicated process group are zombies. (This is consistent with the
    behavior of BSD systems.)

  RETURN VALUES

    The setpgid(2) call returns 0 when the operation was successful. If the
    request failed, -1 is returned and the global variable errno indicates the
    reason.

  ERRORS

    The setpgid(2) call will fail and the process group will not be altered
    if:

    [EACCES]
        The value of pid matches the process ID of a child process and the
        child process has successfully executed one of the exec functions.

    [EINVAL]
        The value of the pgid argument is non-zero, is not equal to the ID of
        the indicated process, and is not equal to to the ID of any existing
        process group.

    [EPERM]
        The process indicated by pid is a session leader.
        The value of pid 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 process.
        The value of pgrp is valid, but does not match the process ID of the
        process indicated by pid and there is no process with a process group
        ID that matches pgid in the same session as the calling process.

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

  SEE ALSO

    getpgrp(2)

    setsid(2)

    tcsetpgrp(2)

  USAGE NOTES

    The setpgid function is thread safe.

    The setpgid function is async-signal safe.