git 练习笔记

准备工作

git clone https://github.com/ruby/ruby ~/github/ruby

本次练习用到的子命令包括

• git checkout
• git log (--oneline, --author, and -S will be useful)
• git diff (--stat will be useful)
• git show
• git status

练习

对 git 不太熟悉，不能保证一定是正确的，而且还用到了除了 git 之外的工具，如果有发现错误或者更好的实现方法，请不吝赐教，谢谢。

Check out matz’s commit of Ruby from 1998. The commit ID is 3db12e8b236ac8f88db8eb4690d10e4a3b8dbcd4. Find out how many lines of code Ruby was at that time.

git checkout 3db12e8b236ac8f88db8eb4690d10e4a3b8dbcd4
git branch

* (头指针分离于 3db12e8b23)
  master

Check out the current master branch

git checkout master
git branch

您的分支与上游分支 'origin/master' 一致。
* master

Look at the history for the file hash.c. What was the last commit ID that changed that file?

git log --oneline -n 1 hash.c

21994b7fd6 Avoid rehashing keys in transform_values

Get a diff of how hash.c has changed in the last 20ish years: compare that file on the master branch to the file at commit 3db12e8b236ac8f88db8eb4690d10e4a3b8dbcd4.

git diff master 3db12e8b236ac8f88db8eb4690d10e4a3b8dbcd4 hash.c  |head -n 20

diff --git a/hash.c b/hash.c
index e9d994bf70..fe9dfbaa26 100644
--- a/hash.c
+++ b/hash.c
@@ -1,6290 +1,1005 @@
-/**********************************************************************
+/************************************************

   hash.c -

   $Author$
+  $Date$
   created at: Mon Nov 22 18:51:18 JST 1993

-  Copyright (C) 1993-2007 Yukihiro Matsumoto
-  Copyright (C) 2000  Network Applied Communication Laboratory, Inc.
-  Copyright (C) 2000  Information-technology Promotion Agency, Japan
-
-**********************************************************************/
-

Find a recent commit that changed hash.c and look at the diff for that commit

lastchange=$(git log --oneline -n 2 hash.c |tail -n 1 |cut -f1 -d " ")
git diff master ${lastchange} hash.c |head

diff --git a/hash.c b/hash.c
index e9d994bf70..b61784af3a 100644
--- a/hash.c
+++ b/hash.c
@@ -3129,16 +3129,10 @@ rb_hash_transform_keys_bang(VALUE hash)
 }

 static int
-transform_values_foreach_func(st_data_t key, st_data_t value, st_data_t argp, int error)
+transform_values_i(VALUE key, VALUE value, VALUE result)

This repository has a bunch of tags for every Ruby release. Get a list of all the tags.

git tag |head

REXML_2_7_0
SHELL_v0_6
forwardable_v1_1
gtk_012
irb_0_7_1
irb_0_7_3
irb_0_9
net_1_1_1
net_1_1_3
oniguruma_2_2_4

Find out how many files changed between tag v1_8_6_187 and tag v1_8_6_188

git diff v1_8_6_187 v1_8_6_188 --stat

ChangeLog                          | 10 ++++++++++
ext/Win32API/lib/win32/registry.rb |  2 +-
ext/Win32API/lib/win32/resolv.rb   |  2 +-
lib/resolv.rb                      |  2 +-
version.h                          |  2 +-
5 files changed, 14 insertions(+), 4 deletions(-)

Find a commit (any commit) from 2015 and check it out, look at the files very briefly, then go back to the master branch.

commit=$(git log --oneline -n 1 --until 2015-01-01 |cut -f1 -d " ")
git checkout "${commit}"
git branch
ls |head
git checkout master
git branch

* (头指针分离于 d03c86391b)
  master
addr2line.c
addr2line.h
array.c
benchmark
bignum.c
bin
bootstraptest
BSDL
ccan
ChangeLog
您的分支与上游分支 'origin/master' 一致。
* master

Find out what commit the tag v1_8_6_187 corresponds to.

git rev-list -n 1 v1_8_6_187

928e6916b25aee5b2b379999a3fa8816d40db714

List the directory .git/refs/tags. Run cat .git/refs/tags/v1_8_6_187 to see the contents of one of those files.

ls .git/refs/tags
echo -------------------------------------------
cat .git/refs/tags/v1_8_6_187

-------------------------------------------

这个题目好奇怪， .git/refs/tags 里居然是空的，感觉有什么地方不对。

Find out what commit ID HEAD corresponds to right now.

git rev-list -n 1 HEAD

38069a3a55325757d2bba84191b006361a284cb0

Find out how many commits have been made to the test/ directory

git log --oneline -- test |wc -l

12370

Find out what commit ID HEAD corresponds to right now.

git rev-list -n 1 HEAD

38069a3a55325757d2bba84191b006361a284cb0

Get a diff of lib/telnet.rb between the commits 65a5162550f58047974793cdc8067a970b2435c0 and 9e3d9a2a009d2a0281802a84e1c5cc1c887edc71. How many lines of that file were changed?

git diff --stat 65a5162550f58047974793cdc8067a970b2435c0  9e3d9a2a009d2a0281802a84e1c5cc1c887edc71 -- lib/telnet.rb

lib/telnet.rb | 58 ++++++++++++++++++++++++++++++++++++++++++++--------------
1 file changed, 44 insertions(+), 14 deletions(-)

How many commits were made between Ruby 2.5.1 and 2.5.2 (tags v2_5_1 and v2_5_3) (this one is a tiny bit tricky, there’s more than one step)

git log --oneline v2_5_1..v2_5_2 |wc -l

49

How many commits were authored by matz (Ruby’s creator)?

git log --oneline --author=matz |wc -l

2562

What’s the most recent commit that included the word tkutil?

git log -n 1 --grep tkutil

commit c285a4e3578c30b074f665e5f63283800fe3e157
Author: nobu <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date:   Mon May 23 04:31:55 2016 +0000

    remove unnecessary volatiles

    * ext/dbm/dbm.c (fdbm_initialize): used for rb_sys_fail_str.

    * ext/sdbm/init.c (fsdbm_initialize): ditto.

    * ext/tk/tcltklib.c (lib_do_one_event_core): no effect.

    * ext/tk/tkutil/tkutil.c (tk_eval_cmd, tk_get_eval_string): no
      effect if tail call optimized.

    * ext/tk/tkutil/tkutil.c (cbsubst_table_setup): set to const.

    git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@55127 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

Check out the commit e51dca2596db9567bd4d698b18b4d300575d3881 and create a new branch that points at that commit.

git branch new e51dca2596db9567bd4d698b18b4d300575d3881 
git branch

* master
  new

Run git reflog to see all the navigating of the repository you’ve done so far

git reflog

5b1fd79ad9 HEAD@{0}: pull: Fast-forward
0e84eecc17 HEAD@{1}: pull: Fast-forward
142efba93e HEAD@{2}: pull: Fast-forward
2272efa463 HEAD@{3}: pull: Fast-forward
c020fd6aa8 HEAD@{4}: pull: Fast-forward
70fd022a2a HEAD@{5}: pull: Fast-forward
38069a3a55 HEAD@{6}: checkout: moving from d03c86391b52e8470fb5b31c58ebc2422ec1653b to master
d03c86391b HEAD@{7}: checkout: moving from master to d03c86391b
38069a3a55 HEAD@{8}: checkout: moving from master to master
38069a3a55 HEAD@{9}: checkout: moving from d03c86391b52e8470fb5b31c58ebc2422ec1653b to master
d03c86391b HEAD@{10}: checkout: moving from master to d03c86391b
38069a3a55 HEAD@{11}: checkout: moving from d03c86391b52e8470fb5b31c58ebc2422ec1653b to master
d03c86391b HEAD@{12}: checkout: moving from master to d03c86391b
38069a3a55 HEAD@{13}: checkout: moving from d03c86391b52e8470fb5b31c58ebc2422ec1653b to master
d03c86391b HEAD@{14}: checkout: moving from master to d03c86391b
38069a3a55 HEAD@{15}: checkout: moving from d03c86391b52e8470fb5b31c58ebc2422ec1653b to master
d03c86391b HEAD@{16}: checkout: moving from master to d03c86391b
38069a3a55 HEAD@{17}: pull: Fast-forward
0785469a40 HEAD@{18}: pull: Fast-forward
3bb1162cac HEAD@{19}: pull: Fast-forward
4a403e3f98 HEAD@{20}: pull: Fast-forward
6cad064424 HEAD@{21}: pull: Fast-forward
1edcfd6107 HEAD@{22}: pull: Fast-forward
8263459627 HEAD@{23}: pull: Fast-forward
f41cd4ba43 HEAD@{24}: pull: Fast-forward
b2c29bbab6 HEAD@{25}: pull: Fast-forward
7e0f56fb3d HEAD@{26}: pull: Fast-forward
ac3e8834e0 HEAD@{27}: checkout: moving from 3db12e8b236ac8f88db8eb4690d10e4a3b8dbcd4 to master
3db12e8b23 HEAD@{28}: checkout: moving from master to 3db12e8b236ac8f88db8eb4690d10e4a3b8dbcd4
ac3e8834e0 HEAD@{29}: clone: from https://github.com/ruby/ruby