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.
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
seeking, 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 handle 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
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
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.
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 Electrical 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
IEEE/The Open Group 2013 FCLOSE(3P)