close — close a file descriptor
#include <unistd.h>
int
close( |
int | fd) ; |
close
() closes a file
descriptor, so that it no longer refers to any file and may
be reused. Any record locks (see fcntl(2)) held on the file
it was associated with, and owned by the process, are removed
(regardless of the file descriptor that was used to obtain
the lock).
If fd
is the last
copy of a particular file descriptor the resources associated
with it are freed; if the descriptor was the last reference
to a file which has been removed using unlink(2) the file is
deleted.
close
() returns zero on
success. On error, −1 is returned, and errno
is set appropriately.
fd
isn't a
valid open file descriptor.
The close
() call was
interrupted by a signal.
An I/O error occurred.
Not checking the return value of close
() is a common but nevertheless
serious programming error. It is quite possible that errors
on a previous write(2) operation are
first reported at the final close
(). Not checking the return value when
closing the file may lead to silent loss of data. This can
especially be observed with NFS and with disk quota.
A successful close does not guarantee that the data has been successfully saved to disk, as the kernel defers writes. It is not common for a filesystem to flush the buffers when the stream is closed. If you need to be sure that the data is physically stored use fsync(2). (It will depend on the disk hardware at this point.)
fcntl(2), fsync(2), open(2), shutdown(2), unlink(2), fclose(3)
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