Script broken after updating bash to 4.3.46-7?
Mon Sep 5 23:37:00 GMT 2016
Lee, you have a point.
Adding mysql.sh that runs `mysql.exe | d2u`, or using a cygwin version
of mysql looks like the most viable solution at the moment.
Or staying with the older version of bash, in which `read` still
handled `\r\n` line endings...
My point is OK I'll fix that script, who knows what other scripts
might be broken now? And each one might need an investigation before I
find out which program's windows version needs a wrapper script etc.
On 4 September 2016 at 20:37, Lee <firstname.lastname@example.org> wrote:
> On 9/4/16, Gene Pavlovsky wrote:
>> This issue never affected me personally, but it sounds like a serious
>> bug and I'm as glad as anybody that it's finally fixed.
>> However, having existing scripts suddenly breaking is not great. I'd
>> like to remind that I'm not the author of the script in question,
>> If I put "| d2u" there I'll have to remember it and do it every time
>> automysqlbackup is updated ...
> Right - updating something like automysqlbackup to add "| d2u" after
> every dos program call is a non-starter. But would putting the dos
> program inside a script that converted dos -> unix line endings work?
> eg - have a mysql script that comes before the windows version of
> mysql in your path that does something like
> /path/to/windows/version/of/mysql $@ | dos2unix
>> - or create and maintain a Cygwin package for this script.
> It seems to me that it isn't the script that's broken - it's the whole
> idea of having a dos program transparently integrate into an
> environment that expects unix line endings that's broken. So until
> there's a bash option that automatically translates '\r\n' line
> endings into '\n' line endings you're stuck doing some kind of
> work-around or using a cygwin version of mysql.
>> And who knows how many other scripts might be broken,
>> I just didn't find it yet?
>> Having a `read`-specific shell option telling read to treat `\r\n`
>> (and only `\r\n`, not \r followed by something else) same as `\n`
>> would be bad things to have? For me, this kind of option would be more
>> useful than the `igncr` crutch
>> Let me say it another way - in OOP programming, one of good practices
>> is Single Responsibility Principle - a class should be responsible for
>> only one feature/function, and that feature/function should be totally
>> encapsulated in that class. Similar to that, an option should be
>> responsible for one behavior. With this change to `read`, the `igncr`
>> shell option is starting to look like a kitchen sink... split it into
>> separate options, please!
>> I think making UNIX scripts work on Cygwin with no or minimum
>> modifications (or bug-hunting) should be one of high priorities, no?
>> If some scripts erroneously have CRLF line endings, it's easy to find
>> and `d2u` them, rather than using the `igncr` crutch, but with the
>> recent change to `read`, countless scripts might be broken in a
>> non-obvious way. Fixing them would require finding out they're broken,
>> in the first place. Imagine if I didn't set up my cron to e-mail me
>> the cron jobs output? My backup script would just stop working
>> silently, and some time later when I needed a recent backup, I would
>> find out there aren't any. There might be something else lurking that
>> I haven't found yet. Once a script, broken by this change to `read`,
>> is found, it must be checked thoroughly to find out where exactly is
>> the problem, where to put '| d2u', or maybe 'set -o igncr'. These
>> fixes must also be applied anytime a 3rd party script is updated.
>> Quite a lot of work!
>> Hope you will consider my point.
>> On 30 August 2016 at 23:57, cyg Simple <email@example.com> wrote:
>>> On 8/30/2016 1:38 PM, Eric Blake wrote:
>>>> On 08/30/2016 12:04 PM, cyg Simple wrote:
>>>>> On 8/29/2016 2:30 PM, Eric Blake wrote:
>>>>>> Simplest fix:
>>>>>> read ... < <(mysql ... | dos2unix)
>>>>> This will break when the data returned by mysql is supposed to contain
>>>>>> There. Now you aren't feeding \r to read in the first place.
>>>>> But you might want to feed \r to read. It isn't a fix, it is a
>>>>> potential work around dependent on the data set results. If a read
>>>>> is supposed to be reading binary data doesn't pass all of the data to
>>>>> the routine then it is broken.
>>>> Now we're talking past each other.
>>>> That's what the recent bash fixed. 'read' in bash 3.2.42-4 was broken -
>>>> it corrupted binary data, with no recourse, by eating \r (and worse, by
>>>> sometimes eating the byte after \r). 'read' in bash 3.2.46-7 is fixed -
>>>> by default it is strictly binary (all bytes are read as-is, including
>>>> \r), but can also be switched to text mode (using 'igncr', all \r are
>>>> ignored). If you want to preserve mid-line \r but treat line endings of
>>>> \r\n as a single byte, then leave binary mode on and strip the line
>>>> endings via a separate tool like d2u (note, however, that it is very
>>>> rare to have data where mid-line \r is important but line-ending \r\n
>>>> should be treated as plain \n).
>>>> I strongly think that using igncr is a crutch, and you normally
>>>> shouldn't use it; particularly not if you want to be portable to other
>>>> platforms. Instead, massaging your data through d2u is a great way to
>>>> be portable. But sometimes the ease of ignoring ALL \r is easier than
>>>> worrying about portability, so I keep the 'igncr' code in Cygwin.
>>>> And it is only because the OP tried using 'igncr' in the first place
>>>> (whether or not it was actually needed) that we have now flushed out the
>>>> existence of a latent bug in the 'igncr' implementation that interacts
>>>> weirdly with $()\n in PS1. On that front, I'm still hoping to find time
>>>> to debug and/or for someone to post a patch. But whether PS1 behaves
>>>> weirdly under 'igncr' is orthogonal to my suggestion above - using
>>>> 'mysql|d2u' is a great way to avoid the need to worry about 'igncr'.
>>> Thank you for the retort Eric. Happy to know that it is fixed which in
>>> the back of my mind I knew already. I can imagine data such as full
>>> message email or a small document data containing \r\n as valid data in
>>> the database field and if you use a line ending conversion utility you
>>> might loose that data.
>>> cyg Simple
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