close(2)                                                       close(2)

  close()

  NAME

    close() - delete a descriptor

  SYNOPSIS

    #include 

    int close (int d)

  DESCRIPTION

    The close(2) call deletes the file descriptor d and makes it available for
    re-use. If the calling process owns any outstanding record locks on the
    file indicated by d, the call unlocks them.

    When all of the file descriptors pointing to a file are deleted, the file
    is removed. If the file is a pipe or a FIFO, any data remaining in the
    pipe or FIFO is discarded. For example, on the last close of a file the
    current seek pointer associated with the file is lost. On the last close
    of a socket(2), the associated naming information and queued data are
    discarded.

    When a process exits, all associated file descriptors are freed, but since
    there is a limit on active descriptors per process, the close(2) function
    call is useful when a large quantity of file descriptors are being
    handled.

    When a process forks (see fork(2)), all descriptors for the new child
    process reference the same objects as they did in the parent before the
    fork. If a new process is then to be run using exec(2), the process would
    normally inherit these descriptors. Most of the descriptors can be
    rearranged with dup2(2) or deleted with close(2) before the execve(2) is
    attempted, but if some of these descriptors will still be needed if the
    execve(2) fails, it is necessary to arrange for them to be closed if the
    execve(2) succeeds. To do this, use the call:

    fcntl(d, F_SETFD, 1)

    which arranges that a descriptor will be closed after a successful execve;
    to restore the default (that is, not to close the descriptor), use the
    call:

    fcntl(d, F_SETFD, 0)

  RETURN VALUES

    Upon successful completion, a value of 0 is returned. Otherwise, a value
    of -1 is returned and the global integer variable errno is set to indicate
    the error.

  ERRORS

    The close(2) call will fail if:

    [EBADF]
        D is not an active descriptor.

    [EINTR]
        An interrupt was received.

  SEE ALSO

    accept(2)

    socket(2)

    exec(2)

    fcntl(2)

    open(2)

    pipe(2)

  USAGE NOTES

    The close function is thread safe.

    The close function is async-signal safe.