git log：显示左边的第二个父节点 [英] git log: show second parent on the left

问题描述

$ b

 ＃！/ bin / bash -e 
 rm -rf示例
 git init例子
 cd例子
 echo 0> file.txt 
 git add file.txt 
 git commit -am初始提交
 git分支branch1 
 echo 1> file.txt 
 git commit -am1（on master）
 git branch branch2 
 git checkout branch1 
 echo 2> file2.txt 
 git add file2.txt 
 git commit -m2（on branch1）
 git merge --no-edit master 
 echo 3> file2.txt 
 git commit -am3（在branch1上）
 git checkout master 
 echo 4> file.txt 
 git commit -am4（on master）
 git checkout branch1 
 git merge --no-edit master 
 echo 5> file2.txt 
 git commit -am5（在分支1上）
 git checkout master 
 git merge --no-edit --no-ff branch1 
 git log  - graph --oneline 
  

我们创建一个分支 branch1 ，从 master 分支中合并它几次，最后合并回到 master 。 p>

git log --oneline --graph 看上去很奇怪。

  * 2c3b97a合并分支'branch1'
 | \ 
 | * 1d722df 5（在分支1上）
 | * 54039b6将分支'master'合并到branch1 
 |中| \ 
 | | / 
 | / | 
 * | d80d82c 4（主人）
 | * 2399286 3（在分支1上）
 | * 9a0cb38将分支'master'合并到branch1 
 |中| \ 
 | | / 
 | / | 
 * | 31df841 1（主人）
 | * 5809072 2（在分支1上）
 | / 
 * 08fc7a6初始提交
  

如果看起来像这样，图表会更简单：

  * 2c3b97a合并分支'branch1'
 | \ 
 | * 1d722df 5（在分支1上）
 | * 54039b6将分支'master'合并到branch1 
 | / |中
 * | d80d82c 4（主人）
 | * 2399286 3（在分支1上）
 | * 9a0cb38将分支'master'合并到branch1 
 | / |中
 * | 31df841 1（主人）
 | * 5809072 2（在分支1上）
 | / 
 * 08fc7a6初始提交
  

正如我所理解的，它看起来不是这样的原因是， git log 总是倾向于在右侧显示每个合并提交的第二个父所以对于每个合并提交，它都必须向右边绕。 （第二个父级是合并的分支;第一个父级是我们合并的分支。）

1. 有一种方法可以说服 git log 来生成我更喜欢的更简单的图表。有一个

    ＃！/ usr / bin / python 
   导入子流程，sys，re 
    
    args = ['git'，'log '，'--pretty = format：％x00％H％x01％h％x01％P％x00'] + sys.argv [1：] 
    
    rows = subprocess.check_output（args）。 split（'\x00'）[1 :: 2] 
    
    seen_commits = set（[row.split（'\x01'）[0] for row in rows]）
    
    print（digraph G {）
   用于行中的行：
   列= row.split（'\x01'）
    commit = columns [0] 
   标签=列[1] 
    print（'{}[label ={}];'。format（commit，label））
   列中的父级[2] .split ''）：
   如果父母==：
   继续
   如果不是父母在seen_commits中：
   继续
    print（'{} - &格式（commit，parent））
    print（}）
     

   如果你把 $ PATH 放在 git-log-dot 和<$ c $如果你输入 git log-dot + git-log-dot ， git / code>。 （这是从 git 作为单独脚本分发时的遗留保留， git-checkout ， git-reset 等）
   
   

   您还需要Graphviz。在macOS上，我使用 brew install graphviz 安装了它;在Ubuntu上我相信你可以用 sudo apt-get graphviz 来安装它。

   可以使用以下命令生成一个PNG文件 git log-dot 就像这样：
   
   

     git log-dot | dot -Tpng -o graph.png 
     

   （在上面的示例中，我还使用了 -Grankdir = LR 使图形保持水平，但默认的垂直方向也很好。）

   
   

   Consider this example git repository.

   #!/bin/bash -e
   rm -rf example
   git init example
   cd example
   echo 0 > file.txt
   git add file.txt
   git commit -am "initial commit"
   git branch branch1
   echo 1 > file.txt
   git commit -am "1 (on master)"
   git branch branch2
   git checkout branch1
   echo 2 > file2.txt
   git add file2.txt
   git commit -m "2 (on branch1)"
   git merge --no-edit master
   echo 3 > file2.txt
   git commit -am "3 (on branch1)"
   git checkout master
   echo 4 > file.txt
   git commit -am "4 (on master)"
   git checkout branch1
   git merge --no-edit master
   echo 5 > file2.txt
   git commit -am "5 (on branch1)"
   git checkout master
   git merge --no-edit --no-ff branch1
   git log --graph --oneline
   

   We create a branch branch1, merge up to it from the master branch a couple of times, and finally merge back to master.

   git log --oneline --graph looks weirdly twisted.

   *   2c3b97a Merge branch 'branch1'
   |\
   | * 1d722df 5 (on branch1)
   | *   54039b6 Merge branch 'master' into branch1
   | |\
   | |/
   |/|
   * | d80d82c 4 (on master)
   | * 2399286 3 (on branch1)
   | *   9a0cb38 Merge branch 'master' into branch1
   | |\
   | |/
   |/|
   * | 31df841 1 (on master)
   | * 5809072 2 (on branch1)
   |/
   * 08fc7a6 initial commit
   

   The graph would be simpler if it looked like this:

   *   2c3b97a Merge branch 'branch1'
   |\
   | * 1d722df 5 (on branch1)
   | *   54039b6 Merge branch 'master' into branch1
   |/|
   * | d80d82c 4 (on master)
   | * 2399286 3 (on branch1)
   | *   9a0cb38 Merge branch 'master' into branch1
   |/|
   * | 31df841 1 (on master)
   | * 5809072 2 (on branch1)
   |/
   * 08fc7a6 initial commit
   

   The reason it doesn't look like that, as I understand it, is that git log always prefers to show the "second parent" of each merge commit on the right-hand side, so for each merge commit it has to snake around to the right. (The "second parent" is the branch merging in; the "first parent" is the branch we're merging into.)

   1. Is there a way to convince git log to generate the simpler graph I'd prefer? There's an old gist from 2013 proposing fixing this ("Let me specify which branches sink to the left"; there are other interesting ideas there, too), but I see no progress on that.
   2. Assuming git log can't do it naturally, is there another git commit graphing tool/library I can use to make a graph like this?

   解决方案

   Thanks to torek's suggestion to try dot (aka Graphviz) I wrote this Python script to generate output in the dot file format. It generates a graph like this, which looks pretty good to me:

   #!/usr/bin/python
   import subprocess, sys, re
   
   args = ['git', 'log', '--pretty=format:%x00%H%x01%h%x01%P%x00'] + sys.argv[1:]
   
   rows = subprocess.check_output(args).split('\x00')[1::2]
   
   seen_commits = set([row.split('\x01')[0] for row in rows])
   
   print("digraph G {")
   for row in rows:
       columns = row.split('\x01')
       commit = columns[0]
       label = columns[1]
       print('"{}" [label="{}"];'.format(commit, label))
       for parent in columns[2].split(' '):
           if parent == "":
               continue
           if not parent in seen_commits:
               continue
           print('"{}" -> "{}"'.format(commit, parent))
   print("}")
   

   If you put that file on your $PATH as git-log-dot and chmod +x git-log-dot, git will automatically run it if you type git log-dot. (It's a legacy holdover from when git was distributed as separate scripts, git-checkout, git-reset, etc.)

   You'll also need Graphviz. On macOS I installed it with brew install graphviz; on Ubuntu I believe you can install it with sudo apt-get graphviz.

   You can generate a PNG file using git log-dot like so:

   git log-dot | dot -Tpng -o graph.png
   

   (In the sample above, I also used -Grankdir=LR to make the graph horizontal, but the default vertical orientation is pretty good, too.)

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