CODEWITHSUNDEEP
git
mirkokiefer
mirkokiefer

Reputation: 3547

Show git commit history difference

What is the command to get a list of commits that are required to get from commit A to B and in reverse? This would actually be the graph difference between the commit histories of two commits.

Upvotes: 1

Views: 74

Answers (1)

torek
torek

Reputation: 489688

git rev-list can answer these three different, commonly-useful graph-difference questions:

  • commits that are reachable from B but not from A: A..B (or B ^A or B --not A)
  • commits that are reachable from A but not from B: B..A (or similar alternatives)
  • commits on either A or B that are not on their common ancestors: A...B (doesn't matter which order you specify A and B here).

Consider this graph fragment:

-1-2-4-5-A
    \
     3-B

In this case there's no way to go forward from either A to B or vice versa, but you can get the last three commits along the top (4-5-A), or the two along the bottom (3-B), with B..A and A..B respectively. You can get all five of these with A...B. Using both A..B and B..A you can figure out what to remove from A (A itself, then 5, then 4) and then add (3 and B itself), to get "from A to B".

Commits are, as the documentation says, listed "in reverse chronological order by default", but this is also controllable. You probably want --topo-order and sometimes --reverse.

However, in the presence of complex topology, a simple sequence like the above ("remove this, add that") is not sufficient. For instance:

...-x-o-o-o-o-o-B
     \   /   /
      A-o-o-o

All of the o nodes may be important to get "from A to B", but now, no purely linear traversal (commit X before commit Y, then commit Z) can reconstruct the full graph: you need more information (e.g., listing the parents associated with each commit). git rev-list can do all of this; read and study the man page examples closely.

Upvotes: 1

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