Git系列讲解（四）：提交记录之git log与git blame的使用

大家好，欢迎来到IT知识分享网。

git log命令提供了很多子选项，善于使用这些选项可以加快工程师调查问题的效率，下面以ccache的项目举例讲解。

1. git log

完整的commit id，作者，提交日期，注释

2. pretty模式 [ git log –pretty= ]

这个pretty可以理解为对git log默认输出的美化，包含几个子选项，使用者可依据自己的需求选择其一使用。

2.1 git log –pretty=email

2.2 git log –pretty=full

2.3 git log –pretty=fuller

2.4 git log –pretty=medium

2.5 git log –pretty=oneline

2.6 git log –pretty=raw

2.7 git log –pretty=short

2.8 git log –pretty=format:

format的选项太多了，这里就不细讲了，下面是从手册中摘抄的说明，读者有时间可以根据自己的需要进行学习。

· %H: commit hash · %h: abbreviated commit hash · %T: tree hash · %t: abbreviated tree hash · %P: parent hashes · %p: abbreviated parent hashes · %an: author name · %aN: author name (respecting .mailmap, see git-shortlog(1) or git-blame(1)) · %ae: author email · %aE: author email (respecting .mailmap, see git-shortlog(1) or git-blame(1)) · %ad: author date (format respects --date= option) · %aD: author date, RFC2822 style · %ar: author date, relative · %at: author date, UNIX timestamp · %ai: author date, ISO 8601-like format · %aI: author date, strict ISO 8601 format · %cn: committer name · %cN: committer name (respecting .mailmap, see git-shortlog(1) or git-blame(1)) · %ce: committer email · %cE: committer email (respecting .mailmap, see git-shortlog(1) or git-blame(1)) · %cd: committer date (format respects --date= option) · %cD: committer date, RFC2822 style · %cr: committer date, relative · %ct: committer date, UNIX timestamp · %ci: committer date, ISO 8601-like format · %cI: committer date, strict ISO 8601 format · %d: ref names, like the --decorate option of git-log(1) · %D: ref names without the " (", ")" wrapping. · %e: encoding · %s: subject · %f: sanitized subject line, suitable for a filename · %b: body · %B: raw body (unwrapped subject and body) · %N: commit notes · %GG: raw verification message from GPG for a signed commit · %G?: show "G" for a good (valid) signature, "B" for a bad signature, "U" for a good signature with unknown validity, "X" for a good signature that has expired, "Y" for a good signature made by an expired key, "R" for a good signature made by a revoked key, "E" if the signature cannot be checked (e.g. missing key) and "N" for no signature · %GS: show the name of the signer for a signed commit · %GK: show the key used to sign a signed commit · %gD: reflog selector, e.g., refs/stash@{ 
   1} or refs/stash@{ 
   2 minutes ago}; the format follows the rules described for the -g option. The portion before the @ is the refname as given on the command line (so git log -g refs/heads/master would yield refs/heads/master@{ 
   0}). · %gd: shortened reflog selector; same as %gD, but the refname portion is shortened for human readability (so refs/heads/master becomes just master). · %gn: reflog identity name · %gN: reflog identity name (respecting .mailmap, see git-shortlog(1) or git-blame(1)) · %ge: reflog identity email · %gE: reflog identity email (respecting .mailmap, see git-shortlog(1) or git-blame(1)) · %gs: reflog subject · %Cred: switch color to red · %Cgreen: switch color to green · %Cblue: switch color to blue · %Creset: reset color · %C(...): color specification, as described under Values in the "CONFIGURATION FILE" section of git-config(1). By default, colors are shown only when enabled for log output (by color.diff, color.ui, or --color, and respecting the auto settings of the former if we are going to a terminal). %C(auto,...) is accepted as a historical synonym for the default (e.g., %C(auto,red)). Specifying %C(always,...) will show the colors even when color is not otherwise enabled (though consider just using `--color=always to enable color for the whole output, including this format and anything else git might color). auto alone (i.e. %C(auto)) will turn on auto coloring on the next placeholders until the color is switched again. · %m: left (<), right (>) or boundary (-) mark · %n: newline · %%: a raw % · %x00: print a byte from a hex code · %w([<w>[,<i1>[,<i2>]]]): switch line wrapping, like the -w option of git-shortlog(1). · %<(<N>[,trunc|ltrunc|mtrunc]): make the next placeholder take at least N columns, padding spaces on the right if necessary. Optionally truncate at the beginning (ltrunc), the middle (mtrunc) or the end (trunc) if the output is longer than N columns. Note that truncating only works correctly with N >= 2. · %<|(<N>): make the next placeholder take at least until Nth columns, padding spaces on the right if necessary · %>(<N>), %>|(<N>): similar to %<(<N>), %<|(<N>) respectively, but padding spaces on the left · %>>(<N>), %>>|(<N>): similar to %>(<N>), %>|(<N>) respectively, except that if the next placeholder takes more spaces than given and there are spaces on its left, use those spaces · %><(<N>), %><|(<N>): similar to %<(<N>), %<|(<N>) respectively, but padding both sides (i.e. the text is centered) · %(trailers[:options]): display the trailers of the body as interpreted by git-interpret-trailers(1). The trailers string may be followed by a colon and zero or more comma-separated options. If the only option is given, omit non-trailer lines from the trailer block. If the unfold option is given, behave as if interpret-trailer’s --unfold option was given. E.g., %(trailers:only,unfold) to do both. 

3. 单行输出

3.1 git log –oneline

和git log --pretty=oneline差不多，都是每笔提交一行输出(commitID comment)，不同的是git log --oneline的commit id是缩写的。

当第一行注释和第二行注释之间有空行，就只会显示第一行注释，比如下图的最新提交(80a228c3)，对照git log默认输出的就只显示了第一行注释。

3.2 git log –oneline <file>

以单行模式输出某文件的所有提交记录。

4. 输出每笔提交内容变更量统计

4.1 git log –stat

4.2 git log –stat <file>

输出某文件的所有提交记录及其变更量统计。

5. 输出所有提交的变更内容

5.1 git log -p

输出每笔提交的记录以及其变更内容

5.2 git log -p <file>

输出某文件的所有提交记录及其变更内容。

6. 显示某笔提交的变更情况 [ git show –stat commitID ]

7. 显示某笔提交的变更内容 [ git show commitID ]

8. 指定日期格式 [ git log –date= ]

命令后接下面选项：

9. 依据某条件筛选显示

案例：
现有一个git仓库，master分支包含了笔提交，管理两个文件（1.txt，2.txt）。

git log –grep=”modify 1.txt”

查找commit message中包含”modify 1.txt”的提交。

git log -S “testvar = 1”

我们知道每笔提交都包含文件内容的变更(增加和删除)，-S的作用就是从这些变更内容中找到要查找的内容(testvar = 1)，并将其git日志输出来。注意要和–grep区分开来，–grep搜索的是提交信息，而-S是搜索提交中的变更内容（git管理的文件，代码等）

我们把上面命令稍作修改，变成
git log -S "testvar = 1" --pretty="%H" | xargs git show，这样就可以看到-S筛选出来的三笔提交，其变更内容都是包含了指定内容（testvar = 1）

10. 输出文件每行的提交记录

10.1 git blame <file>

输出指定文件中每行内容的最近一笔提交信息。

10.2 git blame -L <开始行数>,<结束行数> <file>

输出某文件从第几行到第几行的最近一笔提交记录

git blame -L 5,5 <file> 代表第5行的提交记录 git blame <file> | tail -n <行数> 搭配tail命令还可以显示最后多少行的提交记录