X-Recipient: archive-cygwin AT delorie DOT com DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org D0BA43857B9B DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cygwin.com; s=default; t=1687596377; bh=y2sOHipJCo3NLq84X2PGFg23cI+hyQN2SkKiGN5gdxk=; h=Date:Subject:To:References:In-Reply-To:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To: From; b=ge1SALkeOqfkotXzZgk8TYn1RIdVQ4QLvUGbR9C77PbYS6lmO8iS1g45c8sNU/WPX IAiQ9f9d19ZSeUjLnZ64z/6yarHLFxzVXG5s/GgX2do+uU9abn+NAz1SxvWgFtGeKw UBctD8WnAQ7DeIB2nJytYEdem8zO4kJmJ84XDLpc= X-Original-To: cygwin AT cygwin DOT com Delivered-To: cygwin AT cygwin DOT com DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 507583858C31 X-Virus-Scanned: Debian amavisd-new at emo07-pco.easydns.vpn Message-ID: <63908dd8-36ab-9b18-2423-58ec0c41abb9@house.org> Date: Sat, 24 Jun 2023 01:45:33 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.11.0 Subject: Re: scp and ssh 'cat' stalls at 64k bytes Content-Language: en-US, en-CA To: cygwin AT cygwin DOT com References: <1b9482bd-2119-732f-cc49-a3930bd3328d AT house DOT org> <947c6b09-c2c0-03db-a4ac-769c4f1b3783 AT Shaw DOT ca> <7fd038be-e163-a5d3-5e28-d79eef977ee5 AT house DOT org>

<754ed51d-ba50-5268-9150-1c6b5c86b5ca AT house DOT org> <59bddbbd-f934-8a23-3589-31e6db46639d AT harkless DOT org> <1398592771 DOT 3401553 DOT 1687590748417 AT mail DOT yahoo DOT com> In-Reply-To: <1398592771.3401553.1687590748417@mail.yahoo.com> X-Spam-Status: No, score=-2.0 required=5.0 tests=BAYES_00, KAM_DMARC_STATUS, NICE_REPLY_A, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: cygwin AT cygwin DOT com X-Mailman-Version: 2.1.29 List-Id: General Cygwin discussions and problem reports List-Archive: List-Post: List-Help: List-Subscribe: , From: Chris Roehrig via Cygwin Reply-To: Chris Roehrig Content-Type: text/plain; charset="utf-8"; Format="flowed" Sender: "Cygwin" Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by delorie.com id 35O8kf2M026007 On 2023-06-24 00:12, Kevin Schnitzius wrote: > On Friday, June 23, 2023 at 10:00:02 PM EDT, Chris Roehrig via Cygwin wrote: > >> Thanks. There must be some issue with my setup. Very odd that 'pv' >> works, but 'cat' does not. ldd shows they use identical libs. I guess >> I'll start with the pv and cat source. > Try this first: > /usr/bin/dd if=/dev/zero bs=1 count=65536 | /usr/bin/ssh localhost '/usr/bin/cat > /dev/null' Good thought. No change. NB: 65536 always works fine. Anything greater (e.g. 65537) does not work. > Also, I assume you are running Cygwin's bash in a mintty term... Yes, same results with both mintty (Administrator or not) or slogged in remotely. I found another one that works: tee. So these work fine (and /dev/null can be replaced by any file or omitted; doesn't matter): dd if=/dev/urandom bs=1 count=65537 | ssh localhost 'wc' # WORKS dd if=/dev/urandom bs=1 count=65537 | ssh localhost 'tee /dev/null | cat > /dev/null' # WORKS dd if=/dev/urandom bs=1 count=65537 | ssh localhost 'pv | cat > /dev/null' # WORKS dd if=/dev/urandom bs=1 count=65536 | ssh localhost 'cat > /dev/null' # WORKS These don't: dd if=/dev/urandom bs=1 count=65537 | ssh localhost 'cat | wc' # STALLS dd if=/dev/urandom bs=1 count=65537 | ssh localhost 'cat > /dev/null' # STALLS dd if=/dev/urandom bs=1 count=65537 | ssh localhost 'awk {print} > /dev/null' # STALLS dd if=/dev/urandom bs=1 count=65537 | ssh localhost 'sed {} > /dev/null' # STALLS So pv, tee, and wc work, but cat, sed, awk get hung up. I also tried a simple python 3.9 implementation of 'cat' which works, and a gcc-compiled getchar/putchar one which stalls (which gives me something to work with). -- Problem reports: https://cygwin.com/problems.html FAQ: https://cygwin.com/faq/ Documentation: https://cygwin.com/docs.html Unsubscribe info: https://cygwin.com/ml/#unsubscribe-simple