FFLUSHSection: Linux Programmer's Manual (3)
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NAMEfflush - flush a stream
DESCRIPTIONThe function fflush() forces a write of all user-space buffered data for the given output or update stream via the stream's underlying write function. The open status of the stream is unaffected.
If the stream argument is NULL, fflush() flushes all open output streams.
For a non-locking counterpart, see unlocked_stdio(3).
RETURN VALUEUpon successful completion 0 is returned. Otherwise, EOF is returned and errno is set to indicate the error.
- Stream is not an open stream, or is not open for writing.
The function fflush() may also fail and set errno for any of the errors specified for write(2).
CONFORMING TOC89, C99.
NOTESNote that fflush() only flushes the user space buffers provided by the C library. To ensure that the data is physically stored on disk the kernel buffers must be flushed too, for example, with sync(2) or fsync(2).
SEE ALSOfsync(2), sync(2), write(2), fclose(3), fopen(3), setbuf(3), unlocked_stdio(3)
COLOPHONThis page is part of release 3.21 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.