Git 中的 commit-ish 和 tree-ish 是什么？
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/23303549/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
What are commit-ish and tree-ish in Git?
提问by
The Question
问题
What are specific examples of commit-ish and tree-ish in Git?
Git 中 commit-ish 和 tree-ish 的具体例子是什么？
The Stack Overflow question "What does tree-ish mean in git?"deals with tree-ish specifically, but I want to understand more about both.
Stack Overflow 问题“git 中的 tree-ish 是什么意思？” 专门处理 tree-ish ，但我想更多地了解两者。
Background
背景
Usages in Documentation
文档中的用法
The Git documentationmakes several references to "commit-ish" and "tree-ish". For example, if you're examining the Git source code:
Git 文档多次提到“commit-ish”和“tree-ish”。例如，如果您正在检查Git 源代码：
$ git grep --files-with-matches --extended-regexp "commit(-)*ish"
config.txt
git-describe.txt
git-fast-import.txt
git-name-rev.txt
git-push.txt
git-rebase.txt
git-rev-parse.txt
git.txt
gitcli.txt
glossary-content.txt
howto/revert-branch-rebase.txt
revisions.txt
and
和
$ git grep --files-with-matches --extended-regexp "tree(-)*ish" | \
$ grep --invert-match RelNotes
diff-format.txt
diff-generate-patch.txt
git-archive.txt
git-cat-file.txt
git-checkout.txt
git-diff-index.txt
git-diff-tree.txt
git-ls-files.txt
git-ls-tree.txt
git-merge-tree.txt
git-read-tree.txt
git-reset.txt
git-svn.txt
git.txt
gitcli.txt
gittutorial-2.txt
glossary-content.txt
revisions.txt
Definitions
定义
The Git documentation defines what "commit-ish" and "tree-ish" are:
Git 文档定义了“commit-ish”和“tree-ish”是什么：
<tree>Indicates a tree object name.
<commit>Indicates a commit object name.
<tree-ish>Indicates a tree, commit or tag object name. A command that takes a
<tree-ish>argument ultimately wants to operate on a<tree>object but automatically dereferences<commit>and<tag>objects that point at a<tree>.<commit-ish>Indicates a commit or tag object name. A command that takes a
<commit-ish>argument ultimately wants to operate on a<commit>object but automatically dereferences<tag>objects that point at a<commit>.
<tree>表示树对象名称。
<commit>表示提交对象名称。
<tree-ish>表示树、提交或标记对象名称。一个接受
<tree-ish>参数的命令最终想要对一个<tree>对象进行操作，但会自动取消引用<commit>和<tag>指向 a 的对象<tree>。<commit-ish>表示提交或标记对象名称。带有
<commit-ish>参数的命令最终想要对一个<commit>对象进行操作，但会自动取消引用<tag>指向 a 的对象<commit>。
The Documentation isn't Clear Enough
文档不够清楚
Even though the documentation above defines what "commit-ish" and "tree-ish" are, I still find it to be too vague and unclear.
即使上面的文档定义了“commit-ish”和“tree-ish”是什么，我仍然觉得它太模糊和不清楚。
What are specific examples of "commit-ish" and "tree-ish", and how are they different from each other?
“commit-ish”和“tree-ish”的具体例子是什么，它们之间有什么不同？
回答by
The Short Answer (TL;DR)
简答 (TL;DR)
Here's a complete list of commit-ish and tree-ish identifiers (from the Git revisions documentation):
这是一个完整的 commit-ish 和 tree-ish 标识符列表（来自Git 修订文档）：
----------------------------------------------------------------------
| Commit-ish/Tree-ish | Examples
----------------------------------------------------------------------
| 1. <sha1> | dae86e1950b1277e545cee180551750029cfe735
| 2. <describeOutput> | v1.7.4.2-679-g3bee7fb
| 3. <refname> | master, heads/master, refs/heads/master
| 4. <refname>@{<date>} | master@{yesterday}, HEAD@{5 minutes ago}
| 5. <refname>@{<n>} | master@{1}
| 6. @{<n>} | @{1}
| 7. @{-<n>} | @{-1}
| 8. <refname>@{upstream} | master@{upstream}, @{u}
| 9. <rev>^ | HEAD^, v1.5.1^0
| 10. <rev>~<n> | master~3
| 11. <rev>^{<type>} | v0.99.8^{commit}
| 12. <rev>^{} | v0.99.8^{}
| 13. <rev>^{/<text>} | HEAD^{/fix nasty bug}
| 14. :/<text> | :/fix nasty bug
----------------------------------------------------------------------
| Tree-ish only | Examples
----------------------------------------------------------------------
| 15. <rev>:<path> | HEAD:README.txt, master:sub-directory/
----------------------------------------------------------------------
| Tree-ish? | Examples
----------------------------------------------------------------------
| 16. :<n>:<path> | :0:README, :README
----------------------------------------------------------------------
Identifiers #1-14 are all "commit-ish", because they all lead to commits, but because commits also point to directory trees, they all ultimately lead to (sub)directory tree objects, and can therefore also be used as "tree-ish".
标识符 #1-14 都是“commit-ish”，因为它们都导致提交，但因为提交也指向目录树，它们最终都指向（子）目录树对象，因此也可以用作“树” - 是”。
#15 can also be used as tree-ish when it refers to a (sub)directory, but it can also be used to identify specific files. When it refers to files, I'm not sure if it's still considered "tree-ish", or if acts more like "blob-ish" (Git refers to files as "blobs").
#15 在引用（子）目录时也可以用作 tree-ish，但它也可以用于标识特定文件。当它提到文件时，我不确定它是否仍然被认为是“树形”，或者行为更像是“blob-ish”（Git 将文件称为“blob”）。
The Long Answer
长答案
Commits and Directory Trees in Git
Git 中的提交和目录树
At its lowest levels, Git keeps track of source code using four fundamental objects:
在最底层，Git 使用四个基本对象来跟踪源代码：
- Annotated tags, which point to commits.
- Commits, which point to the root directory tree of your project.
- Trees, which are directories and subdirectories.
- Blobs, which are files.
- 带注释的标签，指向提交。
- 提交，指向项目的根目录树。
- 树，即目录和子目录。
- Blob，它们是文件。
Each of these objects has its own sha1 hash ID, since Linus Torvalds designed Git like an content- addressablefilesystem, i.e. files can be retrieved based on their content (sha1 IDs are generated from file content). The Pro Git book gives this example diagram:
这些对象中的每一个都有自己的 sha1 哈希 ID，因为 Linus Torvalds 将 Git 设计为一个内容可寻址的文件系统，即可以根据其内容检索文件（sha1 ID 是从文件内容生成的）。Pro Git book 给出了这个示例图：
Commit-ish vs Tree-ish
Commit-ish 与 Tree-ish
Many Git commands can accept special identifiers for commits and (sub)directory trees:
许多 Git 命令可以接受提交和（子）目录树的特殊标识符：
"Commit-ish" are identifiers that ultimately lead to a commit object. For example,
tag -> commit"Tree-ish" are identifiers that ultimately lead to tree (i.e. directory) objects.
tag -> commit -> project-root-directory
“Commit-ish”是最终导致提交对象的标识符。例如，
tag -> commit“Tree-ish”是最终导致树（即目录）对象的标识符。
tag -> commit -> project-root-directory
Because commit objects always point to a directory tree object (the root directory of your project), any identifier that is "commit-ish" is, by definition, also "tree-ish". In other words, any identifier that leads to a commit object can also be used to lead to a (sub)directory tree object.
由于提交对象始终指向目录树对象（项目的根目录），因此任何“commit-ish”标识符根据定义也是“tree-ish”。换句话说，任何指向提交对象的标识符也可以用来指向（子）目录树对象。
But since directory tree objects never point to commits in Git's versioning system, not every identifier that points to a (sub)directory tree can also be used to point to a commit. In other words, the set of "commit-ish" identifiers is a strict subset of the set of "tree-ish" identifiers.
但由于目录树对象从不指向 Git 版本控制系统中的提交，因此并非每个指向（子）目录树的标识符也可用于指向提交。换句话说，“commit-ish”标识符集合是“tree-ish”标识符集合的严格子集。
The set of tree-ish identifiers that cannot be used as commit-ishare
不能用作 commit-ish的一组 tree-ish 标识符是
<rev>:<path>, which leads directlyto directory trees, not commit objects. For example,HEAD:subdirectory.Sha1 identifiers of directory treeobjects.
<rev>:<path>，这直接导致目录树，而不是提交对象。例如，HEAD:subdirectory。目录树对象的Sha1 标识符。
回答by MikeW
Note for non-native English [sic!] speakers: "-ish" is a suffix that can be applied to an adjective in order to indicate "having qualities like" or "slightly" - see http://chambers.co.uk/search/?query=ish&title=21st
非英语母语 [原文如此！] 发言者的注意事项：“-ish”是一个后缀，可用于形容词以表示“具有类似”或“轻微”的品质 - 请参阅http://chambers.co.uk /search/?query=ish&title=21st
Hence "tree-ish" - like a "tree" .... "commit-ish" - like a "commit"
因此，“tree-ish”——就像一棵“树”......“commit-ish”——就像一个“提交”
eg "Mars appears like a reddish star" ("d" is doubled !); "the food on the plate was not hot, but warmish"
例如“火星看起来像一颗红色的星星”（“d”加倍！）；“盘子里的食物不是热的，而是暖和的”
I believe that this helps explain "what are ..." better, in that it explains the language usage.
我相信这有助于更好地解释“什么是……”，因为它解释了语言用法。
