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The
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 pointer
associated with the file is lost; on the last close of a 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 When a process
exits, all associated file descriptors are freed, but since there is a
limit on active descriptors per processes, the function call is useful
when a large quantity of file descriptors are being handled. When a process
forks (see 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 the process would normally inherit these descriptors.
Most of the descriptors can be rearranged with or deleted with before
the 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 is provided, which arranges
that a descriptor will be closed after a successful execve; the call restores
the default, which is to not close the descriptor.
Upon successful
completion, a value of 0 is returned. Otherwise, a value of -1 is returned
and the global integer variable is set to indicate the error.
will
fail if: is not an active descriptor. An interrupt was received.
conforms to
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