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Annotation of cci/usr/src/man/man2/close.2, revision 1.1.1.1

1.1       root        1: .TH CLOSE 2 "27 July 1983"
                      2: .UC 4
                      3: .SH NAME
                      4: close \- delete a descriptor
                      5: .SH SYNOPSIS
                      6: .B close(d)
                      7: .br
                      8: .B "int d;"
                      9: .SH DESCRIPTION
                     10: The
                     11: \fIclose\fP call deletes a descriptor from the per-process object
                     12: reference table.
                     13: If this is the last reference to the underlying object, then
                     14: it will be deactivated.
                     15: For example, on the last close of a file
                     16: the current \fIseek\fP pointer associated with the file is lost;
                     17: on the last close of a
                     18: .IR socket (2)
                     19: associated naming information and queued data are discarded;
                     20: on the last close of a file holding an advisory lock
                     21: the lock is released; see further
                     22: .IR flock (2).
                     23: .PP
                     24: A close of all of a process's descriptors is automatic on
                     25: .IR exit ,
                     26: but since
                     27: there is a limit on the number of active descriptors per process,
                     28: .I close
                     29: is necessary for programs which deal with many descriptors.
                     30: .PP
                     31: When a process forks (see
                     32: .IR fork (2)),
                     33: all descriptors for the new child process reference the same
                     34: objects as they did in the parent before the fork.
                     35: If a new process is then to be run using
                     36: .IR execve (2),
                     37: the process would normally inherit these descriptors.  Most
                     38: of the descriptors can be rearranged with
                     39: .IR dup2 (2)
                     40: or deleted with
                     41: .I close
                     42: before the
                     43: .I execve
                     44: is attempted, but if some of these descriptors will still
                     45: be needed if the execve fails, it is necessary to arrange for them
                     46: to be closed if the execve succeeds.
                     47: For this reason, the call ``fcntl(d, F_SETFD, 1)'' is provided
                     48: which arranges that a descriptor will be closed after a successful
                     49: execve; the call ``fcntl(d, F_SETFD, 0)'' restores the default,
                     50: which is to not close the descriptor.
                     51: .SH "RETURN VALUE
                     52: Upon successful completion, a value of 0 is returned.
                     53: Otherwise, a value of \-1 is returned and the global integer variable
                     54: .I errno
                     55: is set to indicate the error.
                     56: .SH ERRORS
                     57: .I Close
                     58: will fail if:
                     59: .TP 15
                     60: [EBADF]
                     61: \fID\fP is not an active descriptor.
                     62: .SH "SEE ALSO"
                     63: accept(2), flock(2), open(2), pipe(2), socket(2), socketpair(2),
                     64: execve(2), fcntl(2)

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