Re: ed and ^M: damages files unbeknownst to the user

[Andrew L. Moore]

Does warning that a file contains non-printing
characters really buy anything?  Knowing this, you
were still surprised by the result.  If you are not
sure of a file's format or type, then the `file'
command is appropriate.  A more charitable warning,
perhaps, is `careful with those regular expressions'.
-AM


In message <address@hidden>, Dan Jacobson writes:
>>>>>> "A" == Andrew L Moore <address@hidden> writes:
>
>A> GNU ed is anti-Microsoft.
>A> Try `l'isting the result.  It contains an embedded carriage return (\r).
>
>I'd just like to point out that the user is totally innocent in this
>case.  He did not leave his unix system to edit a Microsoft file, he
>would have no warning that an occasional unix utility would produce
>CR-LF files... so, we have a utility [gnu ed] that will scramble files
>unbeknownst to the user: either giving him "what you see is not what
>you get" or some other problem.
>
>Even if he did edit a microsoft file, don't you agree that it might be
>charitable to clue him in that something might be not as he expects?
>
>That he should use the l command instead of the p command is not
>something you should blame him with after he has already ruined his
>file unbeknownst to him.
>
>Solution: at least a warning could be output, or at least an "?":
>?
>h
>Binary file
>
>which could include all cases where what you see is not what you
>probably get.  I'd say that is the minumum needed... otherwise you've
>got a utility that damages files unbeknownst to the user, which is a
>serious bug.
>
>A> # ed /var/spool/news/out.going/884-1005862565-1  
>A> 658
>A> 1
>A> Newsgroups: tw.bbs.soc.media,tw.bbs.rec.tv
>A> s/$/,soc.culture.taiwan/l
>A> Newsgroups: tw.bbs.soc.media,tw.bbs.rec.tv\r,soc.culture.taiwan$
>
>A> The result is correct with respect to the POSIX standard, I believe.
>A> -AM
>
>A> In message <address@hidden>, Dan Jacobson writes:
>>> While using ed on a file formatted with ^M's at the end of each
>>> line, the output could be quite disturbing:
>>> 
>>> # ed /var/spool/news/out.going/884-1005862565-1  
>>> 658
>>> 1
>>> Newsgroups: tw.bbs.soc.media,tw.bbs.rec.tv
>>> s/$/,soc.culture.taiwan 
>>> ,soc.culture.taiwansoc.media,tw.bbs.rec.tv
>>> u
>>> p
>>> Newsgroups: tw.bbs.soc.media,tw.bbs.rec.tv
>>> s/$/xxx
>>> xxxsgroups: tw.bbs.soc.media,tw.bbs.rec.tv
>>> u
>>> s/tv/tv,soc.culture.taiwan 
>>> Newsgroups: tw.bbs.soc.media,tw.bbs.rec.tv,soc.culture.taiwan 
>>> w
>>> 678
>>> q
>>> 
>>> One seems not to be able to keep track of what ed is thinking from
>>> merely looking at the screen.
>>> 
>>> $ ed --version
>>> GNU ed version 0.2
>-- 
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>