fclose(3p) — Linux manual page


FCLOSE(3P)              POSIX Programmer's Manual             FCLOSE(3P)

PROLOG         top

       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.

NAME         top

       fclose — close a stream

SYNOPSIS         top

       #include <stdio.h>

       int fclose(FILE *stream);

DESCRIPTION         top

       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.1‐2017 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

       After the call to fclose(), any use of stream results in
       undefined behavior.

RETURN VALUE         top

       Upon successful completion, fclose() shall return 0; otherwise,
       it shall return EOF and set errno to indicate the error.

ERRORS         top

       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 file size.

       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 stream.

       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 conditions.

       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.

EXAMPLES         top



       Since after the call to fclose() any use of stream results in
       undefined behavior, fclose() should not be used on stdin, stdout,
       or stderr except immediately before process termination (see the
       Base Definitions volume of POSIX.1‐2017, Section 3.303, Process
       Termination), so as to avoid triggering undefined behavior in
       other standard interfaces that rely on these streams. If there
       are any atexit() handlers registered by the application, such a
       call to fclose() should not occur until the last handler is
       finishing. Once fclose() has been used to close stdin, stdout, or
       stderr, there is no standard way to reopen any of these streams.

       Use of freopen() to change stdin, stdout, or stderr instead of
       closing them avoids the danger of a file unexpectedly being
       opened as one of the special file descriptors STDIN_FILENO,
       STDOUT_FILENO, or STDERR_FILENO at a later time in the

RATIONALE         top




SEE ALSO         top

       Section 2.5, Standard I/O Streams, atexit(3p), close(3p),
       fmemopen(3p), fopen(3p), freopen(3p), getrlimit(3p),
       open_memstream(3p), ulimit(3p)

       The Base Definitions volume of POSIX.1‐2017, stdio.h(0p)

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic
       form from IEEE Std 1003.1-2017, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The
       Open Group Base Specifications Issue 7, 2018 Edition, Copyright
       (C) 2018 by the Institute of Electrical and Electronics
       Engineers, Inc and The Open Group.  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.opengroup.org/unix/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.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group               2017                        FCLOSE(3P)

Pages that refer to this page: stdio.h(0p)close(3p)fdopen(3p)fopen(3p)freopen(3p)open_memstream(3p)stdin(3p)