CLOSE(2)                COMMAND REFERENCE                CLOSE(2)



NAME
     close - delete a descriptor

SYNOPSIS
     close(fd)
     int fd;

DESCRIPTION
     The close call deletes the descriptor fd from the per-
     process object reference table.  If this is the last
     reference to the underlying object, then it is deactivated.
     For example, on the last close of a file the current lseek
     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 flock(2)).

     A close of all a process's descriptors is automatic on exit,
     but since there is a limit on the number of active
     descriptors per process, close is necessary for programs
     which deal with many descriptors.

     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(fd, F_SETFD, 1) is provided,
     which arranges that a descriptor close after a successful
     execve; the call fcntl(fd, F_SETFD, 0) restores the default,
     which leaves the descriptor open instead of closing it.

DIAGNOSTICS
     The close call fails if:

     [EBADF]      Fd is not an active descriptor.

RETURN VALUE
     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.

SEE ALSO
     accept(2), close(2), dup(2), execve(2), fcntl(2), flock(2),
     fork(2), open(2), pipe(2), socket(2), and socketpair(2).






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