How to tell if a file was renamed between two commits

> I'm trying to write a little utility that will extract all the revisions 
> of a particular file.  I start with a git rev-list HEAD -- filename, get 
> the tree objects with git cat-file commit, the file objects with git 
> ls-tree, and finally the file contents themselves with git cat-file 
> blob.  It works, except in the case where the file name was changed.  
> git rev-list is smart enough to track those name changes, but my little 
> revision tracker isn't.  It dies when suddenly there is no file with the 
> right name in the tree.
> 
> So... is there an easy way to work around this?  Is there a way to get, 
> say, rev-list to tell me when the file it is tracking changed names?  Or 
> a git-diff incantation?  I just need something that will tell me given 
> two commits and a file name whether the file was renamed between those 
> two commits and if so what its new name is.  There must be an easy way 
> to do this, but I can't figure out what it is.

> Ron Garret <ron1@flownet.com> wrote:
> > I'm trying to write a little utility that will extract all the revisions 
> > of a particular file.  I start with a git rev-list HEAD -- filename, get 
> > the tree objects with git cat-file commit, the file objects with git 
> > ls-tree, and finally the file contents themselves with git cat-file 
> > blob.  It works, except in the case where the file name was changed.  
> > git rev-list is smart enough to track those name changes, but my little 
> > revision tracker isn't.  It dies when suddenly there is no file with the 
> > right name in the tree.
> > 
> > So... is there an easy way to work around this?  Is there a way to get, 
> > say, rev-list to tell me when the file it is tracking changed names?  Or 
> > a git-diff incantation?  I just need something that will tell me given 
> > two commits and a file name whether the file was renamed between those 
> > two commits and if so what its new name is.  There must be an easy way 
> > to do this, but I can't figure out what it is.
> 
> Maybe use the -M flag to git log, or the --follow flag to
> log/rev-list?

> In article <20100203023219.GA13092@spearce.org>,
>  "Shawn O. Pearce" <spearce@spearce.org> wrote:
> 
> > Ron Garret <ron1@flownet.com> wrote:
> > > I'm trying to write a little utility that will extract all the revisions 
> > > of a particular file.  I start with a git rev-list HEAD -- filename, get 
> > > the tree objects with git cat-file commit, the file objects with git 
> > > ls-tree, and finally the file contents themselves with git cat-file 
> > > blob.  It works, except in the case where the file name was changed.  
> > > git rev-list is smart enough to track those name changes, but my little 
> > > revision tracker isn't.  It dies when suddenly there is no file with the 
> > > right name in the tree.
> > > 
> > > So... is there an easy way to work around this?  Is there a way to get, 
> > > say, rev-list to tell me when the file it is tracking changed names?  Or 
> > > a git-diff incantation?  I just need something that will tell me given 
> > > two commits and a file name whether the file was renamed between those 
> > > two commits and if so what its new name is.  There must be an easy way 
> > > to do this, but I can't figure out what it is.
> > 
> > Maybe use the -M flag to git log, or the --follow flag to
> > log/rev-list?
> 
> Nope.  git log --follow will follow through a name change but won't 
> actually say when the name changed happened or what the previous name of 
> the file was.
> 
> And actually playing around with it some more, it appears that git 
> rev-list doesn't actually track file renames, or at least it doesn't do 
> it all the time.  Weird.  I'm going to have to play around with this 
> some more.
> 
> rg

> In article <20100203023219.GA13092@spearce.org>,
>  "Shawn O. Pearce" <spearce@spearce.org> wrote:
> > > So... is there an easy way to work around this?  Is there a way to get, 
> > > say, rev-list to tell me when the file it is tracking changed names?
> > 
> > Maybe use the -M flag to git log, or the --follow flag to
> > log/rev-list?
> 
> Nope.  git log --follow will follow through a name change but won't 
> actually say when the name changed happened or what the previous name of 
> the file was.
> 
> And actually playing around with it some more, it appears that git 
> rev-list doesn't actually track file renames, or at least it doesn't do 
> it all the time.  Weird.  I'm going to have to play around with this 
> some more.

> Ron Garret <ron1@flownet.com> wrote:
> > In article <20100203023219.GA13092@spearce.org>,
> >  "Shawn O. Pearce" <spearce@spearce.org> wrote:
> > > > So... is there an easy way to work around this?  Is there a way to get, 
> > > > say, rev-list to tell me when the file it is tracking changed names?
> > > 
> > > Maybe use the -M flag to git log, or the --follow flag to
> > > log/rev-list?
> > 
> > Nope.  git log --follow will follow through a name change but won't 
> > actually say when the name changed happened or what the previous name of 
> > the file was.
> > 
> > And actually playing around with it some more, it appears that git 
> > rev-list doesn't actually track file renames, or at least it doesn't do 
> > it all the time.  Weird.  I'm going to have to play around with this 
> > some more.
> 
> Use:
> 
>   git log --format=%H -M --name-status --follow -- path 
> 
> I just tried it:
> 
> $ git log --format=%H -M --name-status --follow 
> gerrit-prettify/src/main/resources/com/google/gerrit/prettify/client/prettify.
> js
> 8db22c85c49814b99639b2e6346583e9be4c289f
> 
> R100    
> gerrit-patch-gwtexpui/src/main/java/com/google/gwtexpui/safehtml/client/
> 544546fcd680f82a88df3e9eba7df8acfadf1e46
> 
> M       
> gerrit-patch-gwtexpui/src/main/java/com/google/gwtexpui/safehtml/client/
> d83ac11a52c1b6d4acae932a8495daf1e9129fdf
> 
> R100    
> gerrit-patch-gwtexpui/src/main/java/com/google/gwtexpui/safehtml/public/
> 44671f5c6929a8f05223dd359182610286ceb98a
> 
> R100    src/main/java/com/google/gerrit/public/prettify20090521/prettify.js   
>   
> 56fc9e3d951b0886c4781a5c8623dbc3da824f30
> 
> A       src/main/java/com/google/gerrit/public/prettify20090521/prettify.js
> 
> 
> Yay, its been renamed 3 times in its life here.  :-)