Table of Contents

Inspecting Git repository

The Three Main States

State Location Description Method of inspection
Commited .git directory Stored in DB git log git show …
Modified Working directory Changed git status git diff
Staged Staging area (.git/index) Changed and marked for next commit to the DB git status

Staging area has many names:

Revision

There are many ways to distinguish a specific commit from Git repository.

  1. SHA (hash) - The SHA-1 algorithm is used to create a unique 40-byte hexadecimal string in many corners of git. The SHA (hash-object cat-file)
  2. (refnames, refs)
    1. Branch reference (heads) - Branches in Git are nothing more than pointers to the commit. Branch reference is a SHA value of the most recent commit and it is updated with each new commit added. (show rev-parse show-ref)
    2. Tag reference - Similar to Branch reference but does not change with new commits. (git describe)
    3. HEAD (@) - Note the capital letters. Points to the current commit. (git describe)
    4. Other like FETCH_HEAD, MERGE_HEAD, CHERRY_PICK_HEAD, ORIG_HEAD
    5. <refname>@{<date>} - For example master@{yesterday}, HEAD@{5 minutes ago}. Note: Date parsing is undocumented but the parser code can be accessed on github.
    6. <refname>@{n} - For example master@{7} returns 7th prior commit from master head.
    7. <refname>@{-n} - For example @{-2} returns 2nd commit checked out before current one.
    8. <branchname>@{upstream} git rev-parse –symbolic-full-name @{u}
    9. <rev>^n
    10. <rev>~n
    11. more …

Walking the tree with ''^'' and ''~''

A =      = A^0
B = A^   = A^1     = A~1
C = A^2  = A^2
D = A^^  = A^1^1   = A~2
E = B^2  = A^^2
F = B^3  = A^^3
G = A^^^ = A^1^1^1 = A~3
H = D^2  = B^^2    = A^^^2  = A~2^2
I = F^   = B^3^    = A^^3^
J = F^2  = B^3^2   = A^^3^2

Tree

(idea taken from here)

<html> <?xml version=“1.0” encoding=“UTF-8” standalone=“no”?>

inline-svg@projects:progit:inspection

</html>

Range

  1. <rev> - ancestors of commit revision
  2. ^<rev>
  3. <rev1>..<rev2> - reachable from rev2 but exclude reachable from rev1 (none is HEAD)
  4. <rev1>…<rev2> - reachable from either but not both (none is HEAD)
  5. more …

http://stackoverflow.com/questions/7251477/what-are-the-differences-between-double-dot-and-triple-dot-in-git-dif

Reflog

“Log of references” - list of updates to the references

git reflog

Diff

Show difference between working directory (or index if –cached) and commited.

Merge-Base

Debugging with Git

blame Line-by-line who last modified line
grep Search files for given expression
bisect Manually switch between commits until the one that introduces a chenge is found

References

https://github.com/MaciejKucia/git_tree