git show previous commit that modified a file without git log

Question

In git we can easily construct revisions pointing to previous commits like HEAD~ HEAD^ and show files on those revisions like

git show HEAD~:myfile

What is the syntax to show the previous version of myfile without first consulting git log to get the commit hash?

I also use fugitive in vim and sometimes needs to open a file's previous version using :Gedit. But I don't know what to supply as argument.

It seems not possible. The "previous version" is ambiguous. For a merge commit, which ancestor is its previous version? — ElpieKay, Sep 28 '17 at 09:53
@ElpieKay I assume the question is looking at the first parent. — Joseph K. Strauss, Sep 28 '17 at 14:24

Joseph K. Strauss · Accepted Answer · 2017-10-18T20:49:22.033

0

git show $(git log -m --first-parent --format=%H HEAD~ -2 -- path/to/file | tail -1):path/to/file

Note: This solution requires you to specify the path twice, and can be quite verbose to type every time. An alias would perhaps be better.

git config alias.prev '! f(){ git show $(git log -m --first-parent --format=%H HEAD~ -2 -- "$1" | tail -1):"$1"; }; f'

To get the previous hash:

git config alias.prevhash '! f(){ git rev-parse $(git log -m --first-parent --format=%H HEAD~ -2 -- "$1" | tail -1):"$1"; }; f'

edited Oct 18 '17 at 20:49

answered Sep 28 '17 at 14:24

Joseph K. Strauss

Thanks. But this still uses git log. Is this the only way of obtaining that hash? – doraemon Oct 01 '17 at 14:02

1 Answers1