From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from conssluserg-02.nifty.com (conssluserg-02.nifty.com [210.131.2.81]) by sourceware.org (Postfix) with ESMTPS id 9CD02388C02A for ; Thu, 6 May 2021 09:16:06 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 9CD02388C02A Received: from Express5800-S70 (v050190.dynamic.ppp.asahi-net.or.jp [124.155.50.190]) (authenticated) by conssluserg-02.nifty.com with ESMTP id 1469FksX026802 for ; Thu, 6 May 2021 18:15:47 +0900 DKIM-Filter: OpenDKIM Filter v2.10.3 conssluserg-02.nifty.com 1469FksX026802 X-Nifty-SrcIP: [124.155.50.190] Date: Thu, 6 May 2021 18:15:59 +0900 From: Takashi Yano To: cygwin@cygwin.com Subject: Re: Screen clearing in CMD without "Legacy Console Mode" Message-Id: <20210506181559.026085c3284c1b92b4aea598@nifty.ne.jp> In-Reply-To: <20210506181238.798ef704f5f7d77a89107ea8@nifty.ne.jp> References: <20210430235358.2ae6daa41e3f0b6cb0daa173@nifty.ne.jp> <20210506181238.798ef704f5f7d77a89107ea8@nifty.ne.jp> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.30; i686-pc-mingw32) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-4.0 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, NICE_REPLY_A, RCVD_IN_DNSWL_NONE, 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: Thu, 06 May 2021 09:16:08 -0000 On Thu, 6 May 2021 18:12:38 +0900 Takashi Yano via Cygwin> wrote: > On Wed, 5 May 2021 15:07:04 +0200 (CEST) > Johannes Schindelin wrote: > > Hi, > > > > On Fri, 30 Apr 2021, Kevin Locke wrote: > > > > > On Fri, 2021-04-30 at 23:53 +0900, Takashi Yano wrote: > > > > On Fri, 30 Apr 2021 08:25:12 -0600 Kevin Locke wrote: > > > >> I'm investigating an issue in Git for Windows[^1], which also affects > > > >> Cygwin. The issue is that, when using CMD (i.e. Command Prompt) on > > > >> Windows 10 1703 or above with "Legacy Console Mode"[^2] disabled, if > > > >> TERM=cygwin is set in the environment, the console is not cleared when > > > >> vi exits. To demonstrate, with Cygwin 3.2.0, in CMD with "Legacy > > > >> Console Mode" disabled: > > > >> > > > >> cd C:\cygwin64 > > > >> set TERM=cygwin > > > >> bin\vi etc\bash.bashrc > > > >> :q > > > >> > > > >> After exiting vi, the console window has not been cleared and content > > > >> from etc\bash.bashrc remains visible, making further use of the console > > > >> difficult until cleared. > > > > > > > > Why on earth do you want to set TERM=cygwin? > > > > If you don't set TERM=cygwin, TERM is automatically set to > > > > xterm-256color, in which the issue does not occur. > > > > TERM=cygwin would be correct right until the time when you toggle > > `ENABLE_VIRTUAL_TERMINAL_PROCESSING` under our feet. > > > > That is, when the Cygwin process is called, this flag is not set, so > > `TERM=xterm-256color` would be incorrect. And then when the Cygwin process > > returns, the flag is set, and the calling process should somehow guess > > that `TERM` should be set differently. > > > > Oh, and you probably expect the caller to then figure out whether the flag > > was _actually_ toggled, just in case we're running on a Windows 10 version > > that is too old to understand that flag. > > > > If you expect CMD to be no longer used after the Cygwin process returns, > > that might be a valid world view. But that is probably not a very tenable > > world view. > > If you don't set TERM, cygwin sets right value automatically. > That is, in the case in which ENABLE_VIRTUAL_TERMINAL_PROCESSING > is not supported, TERM will be set to 'cygwin', otherwise, it > will be set to 'xterm-256color'. > > Why do you want to set TERM? What is wrong with not setting TERM > manually? If you set TERM incorrectly, it is very natural result > that apps does not work correctly. > > > If Cygwin is unable to handle `TERM=cygwin` correctly when > > `ENABLE_VIRTUAL_TERMINAL_PROCESSING` is toggled, then Cygwin should > > definitely, absolutely, with 100% certainty _not_ toggle that flag when > > `TERM` is already set to `cygwin`! > > I don't think so AT ALL. If someone sets TERM to the value other > than 'cygwin' and 'xterm-256color', what do you expect cygwin to > behave? For example, if TERM is set to 'linux', how should cygwin > behave, do you think? > > P.S. > mintty overwrites the TERM at startup even if user sets TERM manually. > Shouldn't cygwin console also overwrite TERM to the correct value? WSL also overwrites TERM value to 'xterm-256color'. -- Takashi Yano