[Unison-hackers] Re: Bug in / patch for Unison 2.12.0's Makefile.OCaml

[Benjamin Pierce]

OK, I'm backing out Nick's proposed change.   Perhaps the discussion 
will converge on something better...

    - B


On Jun 21, 2005, at 12:17 AM, Zvezdan Petkovic wrote:

> On Mon, Jun 20, 2005 at 10:46:14PM -0400, Benjamin Pierce wrote:
>> Thanks for the suggestion, Nick.  I've made this change in the source.
>> (If someone can try it out on Windows, that would be great.)
>
> You might want to retract a part of it. :-)
>
>>>
>>> The literal control-M can be represented by "\r".
>>>
>
> WRONG!
> According to POSIX sed uses _basic_ regular expressions.
> OTOH, awk and egrep use _extended_ REs.
>
>>> This seems to work for me on Ubuntu 5.04 and Solaris as well as OS X
>>> 10.4:
>
> Are you sure about Solaris?
>
>>>
>>> OCAMLLIBDIR=$(shell ocamlc -v | sed -n '$p' | sed -e 's/^Standard
>>> library directory: //' | sed -e 's/\\/\//g' | sed -e 's/\r//g')
>
> This last part doesn't work in most POSIXly correct sed 
> implementations.
> I just tested it on OpenBSD, HP-UX, _and_ Solaris.
>
> The file is:
> aaa
> a^Mb
> bbb
>
> Now,
> $ cat t
> aaa
> b
> bbb
>
> You can't see a in the second line because ^M returns to the beginning
> of the line and prints b over it.  Lets test how sed works:
>
> $ cat t | sed 's/\r//g'
> aaa
> b
> bbb
>
> No change when I redirect the output into the file.
> The ^M is still there.
>
> Now, using Ctrl-V Ctrl-M to type ^M I get.
>
> $ cat t | sed 's/^M//g'
> aaa
> ab
> bbb
>
> Now it works.
> And that is the only way it will work on OpenBSD, HP-UX _and_ Solaris.
>
> Here's a fingerprint of all machines I ran it on without success when 
> \r
> is used.
>
> $ uname -rs
> OpenBSD 3.7
>
> $ uname -rs
> HP-UX B.11.11
>
> $ uname -rs
> SunOS 5.9
>
> The only machine where it succeeded for me is:
>
> $ uname -rs
> Linux 2.6.5-7.155.29-smp
>
>>>
>>> I haven't tested it on Windows.
>>>
>
> Considering that Microsoft Services for UNIX return
>
> 	OpenBSD
>
> when you type
>
> 	string /usr/bin/* | grep BSD
>
> and it seems some very old rip-off version, I'll bet it will work the
> same on Windows on my office machine.
> Now, Cygwin could be a different beast being based on Linux.
>
> The bottom line is that \r in sed is _not_ portable.
> Keep ^M there.
> There's a good reason it was there for so long time.
>
> Welcome to the friendly world of UNIX portability.
> :-)
>
> 	Zvezdan Petkovic
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