Scieneer Common Lisp 1.3.9 online documentation

ext:flush-output &optional stream waitp[Function]

Flush the stream output buffer, writing it to the stream target. When waitp is true, which is the default, then always wait until complete before returning true, otherwise when waitp is false return false without waiting if the operation would block or return true if the operations is complete. Only the immediate stream buffer is flushed. This may cause output to be written if it can not be buffered in the target stream. Useful for writing buffered output of a composite stream into the target stream without flushing all the target streams in a chain of composite streams. Use force-output or finish-output to write all buffered output to the destination. When the write is not completed the function ext:stream-waiting-file-descriptor may be called to find the file descriptor and directions blocked and when ready the function ext:flush-output can be called again when ready to continue the buffer flushing.