From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0C57EC5B57D for ; Fri, 5 Jul 2019 05:29:10 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id C0F9E218A4 for ; Fri, 5 Jul 2019 05:29:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="gpwsyMS6" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C0F9E218A4 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 520056B0003; Fri, 5 Jul 2019 01:29:09 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4D0738E0003; Fri, 5 Jul 2019 01:29:09 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3BF338E0001; Fri, 5 Jul 2019 01:29:09 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from mail-pg1-f200.google.com (mail-pg1-f200.google.com [209.85.215.200]) by kanga.kvack.org (Postfix) with ESMTP id 04DFA6B0003 for ; Fri, 5 Jul 2019 01:29:09 -0400 (EDT) Received: by mail-pg1-f200.google.com with SMTP id a21so4915476pgh.11 for ; Thu, 04 Jul 2019 22:29:08 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:dkim-signature:date:from:to:cc:subject :message-id:in-reply-to:references:mime-version :content-transfer-encoding; bh=qNZyoCrDt9Pu/FvinUTVMXpvuBiR35dmsH196/cAnJA=; b=VgWT+TyfkxNyA+0ZdYgsGjuV6Mdpt6sx0y691YoAMQrPNTyr8+/qGQs2lgWXGV0uph uxFqYLi3MHestUGWQK4D1L4hk1IuflNVvVbSIioDY/pbdx6FzXsvpnubZ2Rzk63LPQHL 9RrOcQIh4Yghuf3byKcj7j7SWmIi4TY0w1dg30vwC4SsRggkCpTSSHcN4kp4o29xPwDv UqI4fW1/jbiFqOZnDbMprp818MJn9zoVgRWgQ1eCXUTnHq1lwfB3R7O6iNWxoz5un5aH vu3SAfDsqcWVaiOPzVqRtbhsU84S6OgNRvXYWov2X1mpboeyP7+i80Z9aaFtpVeCSihL 5S+w== X-Gm-Message-State: APjAAAViLTzWS8yXiVBRLLGDcWaGOrgWZwuh0QyXzgc+8b9BEYqGoDRC ep3fe+ZqHuTIPoSG7fzTy1zCMI0UvYKVkdQIkYLU9bAapjMmJPstwwBNxoJ12cpDRm+iCiteSpw SJuSE8Ji9sUdynCBoghxq30kL9kxWE/vCxr1foOIxtsLW1E1EkLqmixckMk7sKcdDig== X-Received: by 2002:a17:90a:ba94:: with SMTP id t20mr2479338pjr.8.1562304548706; Thu, 04 Jul 2019 22:29:08 -0700 (PDT) X-Google-Smtp-Source: APXvYqwil/LVCDDOEkv9nuyBnq99PMsr+zn4JN2t8f0Uz/gOcpxlWsPj8FLlKWluzukZ/GBPFlgo X-Received: by 2002:a17:90a:ba94:: with SMTP id t20mr2479273pjr.8.1562304548133; Thu, 04 Jul 2019 22:29:08 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1562304548; cv=none; d=google.com; s=arc-20160816; b=tzWYvuT63LpCztzPY+bmhLHtGg//wmoU/kTvBOsgAhqKD33O727l4c70JFYKeAD0y1 e7QZEmiven0UDRC7UqjEn5lwAoh3pDv2f6b7bYhS8lOJAZIi4YT80acPAmDV3KwbVm+Y edsV4dW5yR9g//cZljLuVGiuInZ92z5Oo7LA9XGmBtqYs3bu55QfleCZXM0G2rY9zlHo SZqiAQJDlUcxHalcexc9/S/RUFn8xN3jzoqFOKEW7OTsurSuY0vPYrY5hHpeMWljHrht LAUMnfVYyT0wwpgoJ1KZoZJ4Iyyib2+w0dcPkWaU5J21AJ/1TMiwVMEpqlXZIr2H+pSl MoJg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:dkim-signature; bh=qNZyoCrDt9Pu/FvinUTVMXpvuBiR35dmsH196/cAnJA=; b=VMiPJrNqfZWhejS7S4Wnx4oe0aI7+V8e3/MKTN0XivXqpFLE6JGwGx4RuBo8byFZ3K fRxzAsb+qPswngWdx5sWYUlGWbj1GqQIaIXhFnprtBc7u24frcLAqiKqEAN1CPKArNej xWPion4uqHKoE6TCLjzHbaLQ0IV+FeSakyjw3Czzwn4M4b9wjRTTLIZDh+OG4WC1o2hZ Ees1BuZCldSb21QvKpm/mv0OvROaLdRKKc9Mb0yk/p8MpmU484/Smd+CIi2xC0wYUVu9 ydVWlbnDoz+OEwd8CkQwMaUpZuH9yeAgcAEQ2hDgRSSQ++K+pRXPnzx6WGgfWPvnZKGI RcvA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=gpwsyMS6; spf=pass (google.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org Received: from mail.kernel.org (mail.kernel.org. [198.145.29.99]) by mx.google.com with ESMTPS id 63si7587277pfg.192.2019.07.04.22.29.07 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 04 Jul 2019 22:29:08 -0700 (PDT) Received-SPF: pass (google.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) client-ip=198.145.29.99; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=gpwsyMS6; spf=pass (google.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org Received: from localhost.localdomain (c-73-223-200-170.hsd1.ca.comcast.net [73.223.200.170]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 111B621850; Fri, 5 Jul 2019 05:29:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1562304547; bh=ku9aEp+wapV1jAtHr82zZH6REpuJWRVS+GCf+tHXR7Y=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=gpwsyMS6DRC1CwjjTw4nWYbfs5wE2bJ85FBSXW84XxfeYBs6quUOEtr8MLEJ6QcMZ 03jv6nY0lDeUSDRQOggVvU24ZcWC8z5wMyc53vkGgU4qbFnuhBeU8cBq+krJtoDFTV 5BAl2jqKEoiqIRjP7Qf7cwvYh0pBZRG2A96dQtGc= Date: Thu, 4 Jul 2019 22:29:06 -0700 From: Andrew Morton To: Joe Perches Cc: Stephen Rothwell , Masahiro Yamada , Randy Dunlap , Mark Brown , linux-fsdevel@vger.kernel.org, Linux Kernel Mailing List , linux-mm@kvack.org, Linux-Next Mailing List , mhocko@suse.cz, mm-commits@vger.kernel.org, Michal Wajdeczko , Daniel Vetter , Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , Intel Graphics , DRI , Chris Wilson Subject: Re: mmotm 2019-07-04-15-01 uploaded (gpu/drm/i915/oa/) Message-Id: <20190704222906.f817d02cb248561edd84a669@linux-foundation.org> In-Reply-To: <5f4680cce78573ecfbbdc0dfca489710581b966f.camel@perches.com> References: <20190704220152.1bF4q6uyw%akpm@linux-foundation.org> <80bf2204-558a-6d3f-c493-bf17b891fc8a@infradead.org> <20190705131435.58c2be19@canb.auug.org.au> <20190704220931.f1bd2462907901f9e7aca686@linux-foundation.org> <5f4680cce78573ecfbbdc0dfca489710581b966f.camel@perches.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, 04 Jul 2019 22:22:41 -0700 Joe Perches wrote: > > So when comparing a zero-length file with a non-existent file, diff > > produces no output. > > Why use the -N option ? > > $ diff --help > [...] > -N, --new-file treat absent files as empty > > otherwise > > $ cd $(mktemp -d -p .) > $ touch x > $ diff -u x y > diff: y: No such file or directory Without -N diff fails and exits with an error. -N does what's desired as long as the non-missing file isn't empty.