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28 .\" @(#)close.2 8.2 (Berkeley) 4/19/94
35 .Nd delete a descriptor
45 system call deletes a descriptor from the per-process object
47 If this is the last reference to the underlying object, the
48 object will be deactivated.
49 For example, on the last close of a file
52 pointer associated with the file is lost;
53 on the last close of a
55 associated naming information and queued data are discarded;
56 on the last close of a file holding an advisory lock
57 the lock is released (see further
59 However, the semantics of System V and
63 advisory record locks associated with a file for a given process
66 file descriptor for that file is closed by that process.
69 all associated file descriptors are freed, but since there is
70 a limit on active descriptors per processes, the
73 is useful when a large quantity of file descriptors are being handled.
75 When a process forks (see
77 all descriptors for the new child process reference the same
78 objects as they did in the parent before the fork.
79 If a new process is then to be run using
81 the process would normally inherit these descriptors.
83 of the descriptors can be rearranged with
89 is attempted, but if some of these descriptors will still
90 be needed if the execve fails, it is necessary to arrange for them
91 to be closed if the execve succeeds.
92 For this reason, the call
93 .Dq Li fcntl(d, F_SETFD, FD_CLOEXEC)
95 which arranges that a descriptor will be closed after a successful
97 .Dq Li fcntl(d, F_SETFD, 0)
99 which is to not close the descriptor.
105 system call will fail if:
111 is not an active descriptor.
113 An interrupt was received.
115 The underlying object did not fit, cached data was lost.
117 The underlying object was a stream socket that was shut down by the peer
118 before all pending data was delivered.
121 In case of any error except
123 the supplied file descriptor is deallocated and therefore is no longer valid.
137 system call is expected to conform to