Re: how to track the history of a line in a file

> On Fri, 2 Jan 2009, david@lang.hm wrote:
>
>> On Fri, 2 Jan 2009, Jeff King wrote:
>> 
>>> The tricky thing here is what is "this line"? Using the line number
>>> isn't right, since it will change based on other content coming in and
>>> out of the file. You can keep drilling down by reblaming parent commits,
>>> but remember that each time you do that you are manually looking at the
>>> content and saying "Oh, this is the line I am still interested in." So I
>>> a script would have to correlate the old version and new version of the
>>> line and realize how to follow the "interesting" thing.
>>> 
>>> In your case, I think you want to see any commit in Makefile which
>>> changed a line with SUBLEVEL in it. Which is maybe easiest done as:
>>>
>>>  git log -z -p Makefile |
>>>    perl -0ne 'print if /\n[+-]SUBLEVEL/' |
>>>    tr '\0' '\n'
>>> 
>>> and is pretty fast. But obviously we're leveraging some content-specific
>>> knowledge about what's in the Makefile.
>> 
>> Ok, I hacked togeather a quick bash script to try this
>> 
> <SNIP>
>> the problem that this has is that line 3 of $COMMIT may not be line 3 of 
>> $COMMIT^, and if they aren't it ends up hunting down the wrong data
>> 
>> either that or I am not understanding the output of git blame properly 
>> (also very possible)
>
> I was misunderstanding git blame
>
> new script is
>
> #!/bin/bash
> line=`git blame -n -b -l -L /$1/,+1 -M $2`
> echo "-$line"
> foundCOMMIT=`echo "$line" |cut -c -40`
> foundline=`echo "$line" |cut -c 42- |cut -f 1 -d " "`
> while [ "$foundCOMMIT" != "                                        " ] ;do
> #git diff -U0 $foundCOMMIT..$foundCOMMIT^ $2
> line=`git blame -n -b -l -L $foundline,+1 -M $2 $foundCOMMIT^`
> echo "-$line"
> foundCOMMIT=`echo "$line" |cut -c -40`
> foundline=`echo "$line" |cut -c 42- |cut -f 1 -d " "`
> done
>
> this seems to be working for me now.