Bug #110028 for rename: \0

Wed Dec 02 18:07:38 2015 glen.mevel [...] crans.org - Ticket created

Subject:	\0
Date:	Thu, 3 Dec 2015 00:07:13 +0100
To:	bug-rename [...] rt.cpan.org
From:	Glen Mével <glen.mevel [...] crans.org>

hello, i had an unexpected (and quite annoying, as i lost a big dataset) behaviour with (perl-)rename 1.9 (both the one packaged for Archlinux and the one found at <http://search.cpan.org/~pederst/rename/>, which are identical saved from two lines), when using a \0 back-reference. $ uname -a Linux hal 4.2.3-1-ARCH #1 SMP PREEMPT Sat Oct 3 19:08:23 CEST 2015 i686 GNU/Linux $ perl -v This is perl 5, version 22, subversion 0 (v5.22.0) built for i686-linux-thread-multi $ pacman -Ss perl-rename community/perl-rename 1.9-1 [installé] $ echo this is aa > aa $ echo this is bb > bb $ ls |sed 's/^./x\0/' # this is what is commonly expected xaa xbb $ perl-rename -v 's/^./x\0/' * # this is what perl-rename claims to do # (wrong w·r·t· what precedes) … aa -> xa bb -> xb $ ls # … and this is what it really does (wrong anyway!) x $ cat x this is bb -- regards, Glen Mével

Thu Dec 03 18:00:05 2015 pederst [...] cpan.org - Correspondence added

On Wed Dec 02 18:07:38 2015, glen.mevel@crans.org wrote: Show quoted text

> hello, > > i had an unexpected (and quite annoying, as i lost a big dataset) > behaviour with (perl-)rename 1.9 (both the one packaged for Archlinux > and the one found at <http://search.cpan.org/~pederst/rename/>, which > are identical saved from two lines), when using a \0 back-reference. > > $ uname -a > Linux hal 4.2.3-1-ARCH #1 SMP PREEMPT > Sat Oct 3 19:08:23 CEST 2015 i686 GNU/Linux > $ perl -v > This is perl 5, version 22, subversion 0 (v5.22.0) > built for i686-linux-thread-multi > $ pacman -Ss perl-rename > community/perl-rename 1.9-1 [installé] > $ echo this is aa > aa > $ echo this is bb > bb > $ ls |sed 's/^./x\0/' > # this is what is commonly expected > xaa > xbb > $ perl-rename -v 's/^./x\0/' * > # this is what perl-rename claims to do > # (wrong w·r·t· what precedes) … > aa -> xa > bb -> xb > $ ls > # … and this is what it really does (wrong anyway!) > x > $ cat x > this is bb >

First of all, \0 is not a backreference in perl as it is in sed, it is the NUL character, chr(0). The output from "rename -v 's/^./x\0/' * -n | hexdump -C" show this, and as you can see, you renamed your files to 'x\0a' and 'x\0b', but as a \0 cant be part of a filename, that means you renamed both files to just 'x' 00000000 61 61 20 2d 3e 20 78 00 61 0a 62 62 20 2d 3e 20 |aa -> x.a.bb -> | 00000010 78 00 62 0a |x.b.| 00000014 If you had used -i with rename, it would have asked you to overwrite: $rename -v 's/^./x\0/' * -i aa -> xa rename: replace `xb'? And as such, rename has done exactly what you asked it to do.

Thu Dec 03 18:00:05 2015 The RT System itself - Status changed from 'new' to 'open'

Thu Dec 03 18:00:29 2015 pederst [...] cpan.org - Taken

Fri Dec 04 07:16:03 2015 glen.mevel [...] crans.org - Correspondence added

Subject:	Re: [rt.cpan.org #110028] \0
Date:	Fri, 4 Dec 2015 13:15:16 +0100
To:	bug-rename [...] rt.cpan.org
From:	Glen Mével <glen.mevel [...] crans.org>

Le 04/12/2015 00:00, Peder Stray via RT a écrit : Show quoted text

> First of all, \0 is not a backreference in perl as it is in sed, it > is the NUL character, chr(0).

oh, i understand better then. i am not really familiar to Perl, so i did not bet \0 to actually mean what in means to sed. what leads me to think there was a bug anyway was the difference between the display and the actual operation. Show quoted text

> but as a \0 cant be part of a filename, that means you renamed both

files to just 'x' maybe it would be adequate to warn the user when trying to use such forbidden characters, to avoid bad suprises of this kind? and/or adjust the display so it corresponds exactly to what is performed? Show quoted text

> If you had used -i with rename, it would have asked you to overwrite

my bad, i just forgot that one (i usually have aliases for this) p·s·: my misadventure was more fear than harm, since i managed to rescue the files with extundelete ;-)

Sun Jan 22 20:41:36 2017 pederst [...] cpan.org - Correspondence added

Ticket migrated to GitHub as https://github.com/pstray/rename/issues/1

Sun Jan 22 20:41:42 2017 pederst [...] cpan.org - Status changed from 'open' to 'resolved'