FCLOSE(3P) POSIX Programmer's Manual FCLOSE(3P)PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the corresponding
Linux manual page for details of Linux behavior), or the interface may
not be implemented on Linux.
NAMEfclose — close a stream
int fclose(FILE *stream);
The functionality described on this reference page is aligned with the
ISO C standard. Any conflict between the requirements described here
and the ISO C standard is unintentional. This volume of POSIX.1‐2008
defers to the ISO C standard.
The fclose() function shall cause the stream pointed to by stream to be
flushed and the associated file to be closed. Any unwritten buffered
data for the stream shall be written to the file; any unread buffered
data shall be discarded. Whether or not the call succeeds, the stream
shall be disassociated from the file and any buffer set by the setbuf()
or setvbuf() function shall be disassociated from the stream. If the
associated buffer was automatically allocated, it shall be deallocated.
If the file is not already at EOF, and the file is one capable of seek‐
ing, the file offset of the underlying open file description shall be
set to the file position of the stream if the stream is the active han‐
dle to the underlying file description.
The fclose() function shall mark for update the last data modification
and last file status change timestamps of the underlying file, if the
stream was writable, and if buffered data remains that has not yet been
written to the file. The fclose() function shall perform the equivalent
of a close() on the file descriptor that is associated with the stream
pointed to by stream.
After the call to fclose(), any use of stream results in undefined
Upon successful completion, fclose() shall return 0; otherwise, it
shall return EOF and set errno to indicate the error.
The fclose() function shall fail if:
EAGAIN The O_NONBLOCK flag is set for the file descriptor underlying
stream and the thread would be delayed in the write operation.
EBADF The file descriptor underlying stream is not valid.
EFBIG An attempt was made to write a file that exceeds the maximum
EFBIG An attempt was made to write a file that exceeds the file size
limit of the process.
EFBIG The file is a regular file and an attempt was made to write at
or beyond the offset maximum associated with the corresponding
EINTR The fclose() function was interrupted by a signal.
EIO The process is a member of a background process group attempting
to write to its controlling terminal, TOSTOP is set, the calling
thread is not blocking SIGTTOU, the process is not ignoring
SIGTTOU, and the process group of the process is orphaned. This
error may also be returned under implementation-defined condi‐
ENOMEM The underlying stream was created by open_memstream() or
open_wmemstream() and insufficient memory is available.
ENOSPC There was no free space remaining on the device containing the
file or in the buffer used by the fmemopen() function.
EPIPE An attempt is made to write to a pipe or FIFO that is not open
for reading by any process. A SIGPIPE signal shall also be sent
to the thread.
The fclose() function may fail if:
ENXIO A request was made of a nonexistent device, or the request was
outside the capabilities of the device.
The following sections are informative.
Section 2.5, Standard I/O Streams, close(), fmemopen(), fopen(), getr‐
limit(), open_memstream(), ulimit()
The Base Definitions volume of POSIX.1‐2008, <stdio.h>
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
cal and Electronics Engineers, Inc and The Open Group. (This is
POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online
at http://www.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the source
files to man page format. To report such errors, see https://www.ker‐
IEEE/The Open Group 2013 FCLOSE(3P)