netdev - RE: sysfs output without newlines

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Message-ID: <5f0b48e0291b4b54bc1caeb8b5715c65@AcuMS.aculab.com>
Date:   Tue, 1 Sep 2020 09:07:42 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Joe Perches' <joe@...ches.com>, Denis Efremov <efremov@...ux.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        "Kees Cook" <keescook@...omium.org>,
        "Gustavo A . R . Silva" <gustavoars@...nel.org>,
        Julia Lawall <julia.lawall@...ia.fr>,
        Alex Dewar <alex.dewar90@...il.com>
CC:     York Sun <york.sun@....com>, Borislav Petkov <bp@...en8.de>,
        "Mauro Carvalho Chehab" <mchehab@...nel.org>,
        Tony Luck <tony.luck@...el.com>,
        "James Morse" <james.morse@....com>,
        Robert Richter <rric@...nel.org>,
        Michal Simek <michal.simek@...inx.com>,
        Boris Brezillon <bbrezillon@...nel.org>,
        "Maxim Levitsky" <maximlevitsky@...il.com>,
        Alex Dubov <oakad@...oo.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Tomas Winkler <tomas.winkler@...el.com>,
        "Arnd Bergmann" <arnd@...db.de>,
        Madalin Bucur <madalin.bucur@....com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        "Douglas Miller" <dougmill@...ux.ibm.com>,
        Stanislav Yakovlev <stas.yakovlev@...il.com>,
        Kalle Valo <kvalo@...eaurora.org>,
        Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>,
        Kai Mäkisara <Kai.Makisara@...umbus.fi>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Mark Brown <broonie@...nel.org>,
        Oliver Neukum <oneukum@...e.com>,
        Pete Zaitcev <zaitcev@...hat.com>,
        "linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-i3c@...ts.infradead.org" <linux-i3c@...ts.infradead.org>,
        "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-wireless@...r.kernel.org" <linux-wireless@...r.kernel.org>,
        "platform-driver-x86@...r.kernel.org" 
        <platform-driver-x86@...r.kernel.org>,
        "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "linux-spi@...r.kernel.org" <linux-spi@...r.kernel.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>
Subject: RE: sysfs output without newlines

From: Joe Perches
> Sent: 29 August 2020 21:34
...
> > On 8/29/20 9:23 PM, Joe Perches wrote:
> > > While doing an investigation for a possible treewide conversion of
> > > sysfs output using sprintf/snprintf/scnprintf, I discovered
> > > several instances of sysfs output without terminating newlines.
> > >
> > > It seems likely all of these should have newline terminations
> > > or have the \n\r termination changed to a single newline.
> >
> > I think that it could break badly written scripts in rare cases.
> 
> Maybe.
> 
> Is sysfs output a nominally unchangeable api like seq_?
> Dunno.  seq_ output is extended all the time.
> 
> I think whitespace isn't generally considered part of
> sscanf type input content awareness.

The shell will remove trailing '\n' (but not '\r') from:
	foo=$(cat bar)
So shell scripts are unlikely to be affected.

	David

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