The fflush function flushes any buffers associated with an open output file or pipe. Many Linux utilities buffer their output (they save information to be written on a disk file or to be output to the screen in their memory until there is enough worthwhile info to share). This buffering saves many I/O operations on disk. If sometimes you need to flush the buffers forcefully, even when the buffer is not full, then you can uses the fflush() function. This forcefully empties the buffers and flushes any buffered info. If no argument is given to the fflush function, then it flushes all open output files and pipes.