GNU bug report logs - #29421
bug in command "tr"

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: wangjian <halfmoonhalf <at> gmail.com>
To: bug-coreutils <at> gnu.org
Subject: bug in command "tr"
Date: Fri, 24 Nov 2017 09:01:43 +0800

Hi there, I think this is a bug

mkdir empty_foler
cd empty_foler
touch a
echo "abc" | tr [:blank:] +  # you will get “+bc” as output, instead of “abc”
touch b
echo "abc" | tr [:blank:]  # you will get “bbc” as output, instead of “abc”

My system info:
CentOS release 6.7 (Final)
linux kernel version 2.6.32-573.el6.x86_64

$ tr --version
tr (GNU coreutils) 8.4
Copyright (C) 2010 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Written by Jim Meyering.
[wangjian <at> kvmhost73 temp]$


Wang

Message #8 received at 29421 <at> debbugs.gnu.org (full text, mbox):

From: Pádraig Brady <P <at> draigBrady.com>
To: wangjian <halfmoonhalf <at> gmail.com>, 29421 <at> debbugs.gnu.org
Subject: Re: bug#29421: bug in command "tr"
Date: Thu, 23 Nov 2017 18:31:13 -0800

tag 29421 notabug
close 29421
stop

On 23/11/17 17:01, wangjian wrote:
> Hi there, I think this is a bug
> 
> mkdir empty_foler
> cd empty_foler
> touch a
> echo "abc" | tr [:blank:] +  # you will get “+bc” as output, instead of “abc”
> touch b
> echo "abc" | tr [:blank:]  # you will get “bbc” as output, instead of “abc”
> 
> My system info:
> CentOS release 6.7 (Final)
> linux kernel version 2.6.32-573.el6.x86_64

You must have a file called "a" in the current directory.
You'll need to quote so the shell doesn't change it on you.
I.E:

  echo "a bc" | tr '[:blank:]' +
  a+bc

cheers,
Pádraig

Message #15 received at 29421 <at> debbugs.gnu.org (full text, mbox):

From: Assaf Gordon <assafgordon <at> gmail.com>
To: wangjian <halfmoonhalf <at> gmail.com>
Cc: 29421 <at> debbugs.gnu.org
Subject: Re: bug#29421: bug in command "tr"
Date: Thu, 23 Nov 2017 19:34:51 -0700

tag 29421 notabug
close 29421
stop

Hello,

On Thu, Nov 23, 2017 at 6:01 PM, wangjian <halfmoonhalf <at> gmail.com> wrote:
> Hi there, I think this is a bug
>
> mkdir empty_foler
> cd empty_foler
> touch a
> echo "abc" | tr [:blank:] +  # you will get “+bc” as output, instead of “abc”
> touch b
> echo "abc" | tr [:blank:]  # you will get “bbc” as output, instead of “abc”

This is not a bug, simply incorrect usage of the parameters on the shell.
Your shell (e.g. bash) expands unquoted [:blank:] to match ANY
file with names matching a/b/l/n/k , and replaces them on the commandline
BEFORE executing 'tr'.
Only if no files match a/b/l/n/k, then the string '[:blank:]' is
passed on to tr as-is.

Observe the following (in an empty directory):

$ echo [:blank:]
[:blank:]

$ touch a
$ echo [:blank:]
a

$ touch b
$ echo [:blank:]
a b

As opposed to using quotes:

$ echo "[:blank:]"
[:blank:]


And so, once you created the files a and b,
the command you executed was equivalent to
    echo abc | tr a b
which indeed results in "bbc".

To avoid such issues, always quote the parameters to 'tr'.

regards,
 - assaf

Message #18 received at 29421 <at> debbugs.gnu.org (full text, mbox):

From: wangjian <halfmoonhalf <at> gmail.com>
To: Assaf Gordon <assafgordon <at> gmail.com>
Cc: 29421 <at> debbugs.gnu.org
Subject: Re: bug#29421: bug in command "tr"
Date: Fri, 24 Nov 2017 13:46:24 +0800

Thanks for your quick response! That was really fantastic and impressive!



> On 24 Nov 2017, at 10:34 am, Assaf Gordon <assafgordon <at> gmail.com> wrote:
> 
> tag 29421 notabug
> close 29421
> stop
> 
> Hello,
> 
> On Thu, Nov 23, 2017 at 6:01 PM, wangjian <halfmoonhalf <at> gmail.com> wrote:
>> Hi there, I think this is a bug
>> 
>> mkdir empty_foler
>> cd empty_foler
>> touch a
>> echo "abc" | tr [:blank:] +  # you will get “+bc” as output, instead of “abc”
>> touch b
>> echo "abc" | tr [:blank:]  # you will get “bbc” as output, instead of “abc”
> 
> This is not a bug, simply incorrect usage of the parameters on the shell.
> Your shell (e.g. bash) expands unquoted [:blank:] to match ANY
> file with names matching a/b/l/n/k , and replaces them on the commandline
> BEFORE executing 'tr'.
> Only if no files match a/b/l/n/k, then the string '[:blank:]' is
> passed on to tr as-is.
> 
> Observe the following (in an empty directory):
> 
> $ echo [:blank:]
> [:blank:]
> 
> $ touch a
> $ echo [:blank:]
> a
> 
> $ touch b
> $ echo [:blank:]
> a b
> 
> As opposed to using quotes:
> 
> $ echo "[:blank:]"
> [:blank:]
> 
> 
> And so, once you created the files a and b,
> the command you executed was equivalent to
>    echo abc | tr a b
> which indeed results in "bbc".
> 
> To avoid such issues, always quote the parameters to 'tr'.
> 
> regards,
> - assaf

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