CLOSE(2)                  386BSD Programmer's Manual                  CLOSE(2)

NAME
     close - delete a descriptor

SYNOPSIS
     #include <unistd.h>

     int
     close(int d)

DESCRIPTION
     The close() call deletes a descriptor from the per-process object
     reference table.  If this is the last reference to the underlying object,
     the object will be deactivated.  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) associated naming information and queued data are
     discarded; on the last close of a file holding an advisory lock the lock
     is released (see further flock(2)).

     When a process exits, all associated file descriptors are freed, but
     since there is a limit on active descriptors per processes, the close()
     function call is useful when a large quanitity 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 execve(2),  the process
     would normally inherit these descriptors.  Most of the descriptors can be
     rearranged with dup2(2) or deleted with close() before the execve is
     attempted, but if some of these descriptors will still be needed if the
     execve fails, it is necessary to arrange for them to be closed if the
     execve succeeds.  For this reason, the call ``fcntl(d, F_SETFD, 1)'' is
     provided, which arranges that a descriptor will be closed after a
     successful execve; the call ``fcntl(d, F_SETFD, 0)'' restores the
     default, which is to not close the descriptor.

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
     Close() will fail if:

     [EBADF]       D is not an active descriptor.

     [EINTR]       An interupt was received.

SEE ALSO
     accept(2),  flock(2),  open(2),  pipe(2),  socket(2),  socketpair(2),
     execve(2),  fcntl(2)

STANDARDS
     Close() conforms to IEEE Std 1003.1-1988 (``POSIX'').

4th Berkeley Distribution       March 10, 1991                               1