From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mailsrv.cs.umass.edu (mailsrv.cs.umass.edu [128.119.240.136]) by sourceware.org (Postfix) with ESMTPS id 148B03959E5D for ; Wed, 24 Feb 2021 21:58:24 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 148B03959E5D Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=cs.umass.edu Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=moss@cs.umass.edu Received: from [192.168.0.100] (c-24-62-203-86.hsd1.ma.comcast.net [24.62.203.86]) by mailsrv.cs.umass.edu (Postfix) with ESMTPSA id B4532401AF46; Wed, 24 Feb 2021 16:58:23 -0500 (EST) Reply-To: moss@cs.umass.edu Subject: Re: Tee and file redirections are very slow to write anything. To: ASSI , cygwin@cygwin.com References: <87eeh5b39n.fsf@Otto.invalid> From: Eliot Moss Message-ID: <49e01de1-f7de-5d60-2996-3c9afb834396@cs.umass.edu> Date: Wed, 24 Feb 2021 16:58:24 -0500 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.12.1 MIME-Version: 1.0 In-Reply-To: <87eeh5b39n.fsf@Otto.invalid> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-2.7 required=5.0 tests=BAYES_00, JMQ_SPF_NEUTRAL, KAM_DMARC_STATUS, NICE_REPLY_A, RCVD_IN_DNSWL_LOW, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: cygwin@cygwin.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: General Cygwin discussions and problem reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 24 Feb 2021 21:58:25 -0000 On 2/24/2021 3:48 PM, ASSI wrote: > Hamish McIntyre-Bhatty via Cygwin writes: >> I found recently when trying to save output from a script for later >> inspection that "tee" and file redirections seem to have massive >> delays when run in Cygwin - usually nothing is written to file or >> stdout until after the command has finished - not very helpful. > > You will want to switch from fully buffered to line-buffered or even > unbuffered output. And this does not have to do with Cygwin. The same happens on Linux. The default is that terminal I/O is unbuffered while other stream are buffered. Pipes come under "other streams". One can make programmatic changes to get around this, but most programs won't override the default behavior on their own ... Best -- Eliot Moss