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1 | SPECIFYING REVISIONS |
2 | -------------------- | |
3 | ||
4 | A revision parameter typically, but not necessarily, names a | |
5 | commit object. They use what is called an 'extended SHA1' | |
6 | syntax. Here are various ways to spell object names. The | |
7 | ones listed near the end of this list are to name trees and | |
8 | blobs contained in a commit. | |
9 | ||
10 | * The full SHA1 object name (40-byte hexadecimal string), or | |
11 | a substring of such that is unique within the repository. | |
12 | E.g. dae86e1950b1277e545cee180551750029cfe735 and dae86e both | |
13 | name the same commit object if there are no other object in | |
14 | your repository whose object name starts with dae86e. | |
15 | ||
16 | * An output from 'git describe'; i.e. a closest tag, optionally | |
17 | followed by a dash and a number of commits, followed by a dash, a | |
18 | `g`, and an abbreviated object name. | |
19 | ||
20 | * A symbolic ref name. E.g. 'master' typically means the commit | |
21 | object referenced by refs/heads/master. If you | |
22 | happen to have both heads/master and tags/master, you can | |
23 | explicitly say 'heads/master' to tell git which one you mean. | |
24 | When ambiguous, a `<name>` is disambiguated by taking the | |
25 | first match in the following rules: | |
26 | ||
27 | . if `$GIT_DIR/<name>` exists, that is what you mean (this is usually | |
28 | useful only for `HEAD`, `FETCH_HEAD`, `ORIG_HEAD` and `MERGE_HEAD`); | |
29 | ||
30 | . otherwise, `refs/<name>` if exists; | |
31 | ||
32 | . otherwise, `refs/tags/<name>` if exists; | |
33 | ||
34 | . otherwise, `refs/heads/<name>` if exists; | |
35 | ||
36 | . otherwise, `refs/remotes/<name>` if exists; | |
37 | ||
38 | . otherwise, `refs/remotes/<name>/HEAD` if exists. | |
39 | + | |
40 | HEAD names the commit your changes in the working tree is based on. | |
41 | FETCH_HEAD records the branch you fetched from a remote repository | |
42 | with your last 'git fetch' invocation. | |
43 | ORIG_HEAD is created by commands that moves your HEAD in a drastic | |
44 | way, to record the position of the HEAD before their operation, so that | |
45 | you can change the tip of the branch back to the state before you ran | |
46 | them easily. | |
47 | MERGE_HEAD records the commit(s) you are merging into your branch | |
48 | when you run 'git merge'. | |
49 | + | |
50 | Note that any of the `refs/*` cases above may come either from | |
51 | the `$GIT_DIR/refs` directory or from the `$GIT_DIR/packed-refs` file. | |
52 | ||
53 | * A ref followed by the suffix '@' with a date specification | |
54 | enclosed in a brace | |
55 | pair (e.g. '\{yesterday\}', '\{1 month 2 weeks 3 days 1 hour 1 | |
56 | second ago\}' or '\{1979-02-26 18:30:00\}') to specify the value | |
57 | of the ref at a prior point in time. This suffix may only be | |
58 | used immediately following a ref name and the ref must have an | |
59 | existing log ($GIT_DIR/logs/<ref>). Note that this looks up the state | |
60 | of your *local* ref at a given time; e.g., what was in your local | |
61 | `master` branch last week. If you want to look at commits made during | |
62 | certain times, see `--since` and `--until`. | |
63 | ||
64 | * A ref followed by the suffix '@' with an ordinal specification | |
65 | enclosed in a brace pair (e.g. '\{1\}', '\{15\}') to specify | |
66 | the n-th prior value of that ref. For example 'master@\{1\}' | |
67 | is the immediate prior value of 'master' while 'master@\{5\}' | |
68 | is the 5th prior value of 'master'. This suffix may only be used | |
69 | immediately following a ref name and the ref must have an existing | |
70 | log ($GIT_DIR/logs/<ref>). | |
71 | ||
72 | * You can use the '@' construct with an empty ref part to get at a | |
73 | reflog of the current branch. For example, if you are on the | |
74 | branch 'blabla', then '@\{1\}' means the same as 'blabla@\{1\}'. | |
75 | ||
76 | * The special construct '@\{-<n>\}' means the <n>th branch checked out | |
77 | before the current one. | |
78 | ||
79 | * The suffix '@\{upstream\}' to a ref (short form 'ref@\{u\}') refers to | |
80 | the branch the ref is set to build on top of. Missing ref defaults | |
81 | to the current branch. | |
82 | ||
83 | * A suffix '{caret}' to a revision parameter (e.g. 'HEAD{caret}') means the first parent of | |
84 | that commit object. '{caret}<n>' means the <n>th parent (i.e. | |
85 | 'rev{caret}' | |
86 | is equivalent to 'rev{caret}1'). As a special rule, | |
87 | 'rev{caret}0' means the commit itself and is used when 'rev' is the | |
88 | object name of a tag object that refers to a commit object. | |
89 | ||
90 | * A suffix '{tilde}<n>' to a revision parameter means the commit | |
91 | object that is the <n>th generation grand-parent of the named | |
92 | commit object, following only the first parent. I.e. rev~3 is | |
93 | equivalent to rev{caret}{caret}{caret} which is equivalent to | |
94 | rev{caret}1{caret}1{caret}1. See below for a illustration of | |
95 | the usage of this form. | |
96 | ||
97 | * A suffix '{caret}' followed by an object type name enclosed in | |
98 | brace pair (e.g. `v0.99.8{caret}\{commit\}`) means the object | |
99 | could be a tag, and dereference the tag recursively until an | |
100 | object of that type is found or the object cannot be | |
101 | dereferenced anymore (in which case, barf). `rev{caret}0` | |
102 | introduced earlier is a short-hand for `rev{caret}\{commit\}`. | |
103 | ||
104 | * A suffix '{caret}' followed by an empty brace pair | |
105 | (e.g. `v0.99.8{caret}\{\}`) means the object could be a tag, | |
106 | and dereference the tag recursively until a non-tag object is | |
107 | found. | |
108 | ||
32574b68 NTND |
109 | * A suffix '{caret}' to a revision parameter followed by a brace |
110 | pair that contains a text led by a slash (e.g. `HEAD^{/fix nasty bug}`): | |
111 | this is the same as `:/fix nasty bug` syntax below except that | |
112 | it returns the youngest matching commit which is reachable from | |
113 | the ref before '{caret}'. | |
114 | ||
5a8f3117 | 115 | * A colon, followed by a slash, followed by a text (e.g. `:/fix nasty bug`): this names |
95ad6d2d | 116 | a commit whose commit message matches the specified regular expression. |
5a8f3117 MG |
117 | This name returns the youngest matching commit which is |
118 | reachable from any ref. If the commit message starts with a | |
119 | '!', you have to repeat that; the special sequence ':/!', | |
120 | followed by something else than '!' is reserved for now. | |
95ad6d2d MM |
121 | The regular expression can match any part of the commit message. To |
122 | match messages starting with a string, one can use e.g. `:/^foo`. | |
5a8f3117 MG |
123 | |
124 | * A suffix ':' followed by a path (e.g. `HEAD:README`); this names the blob or tree | |
125 | at the given path in the tree-ish object named by the part | |
126 | before the colon. | |
127 | ':path' (with an empty part before the colon, e.g. `:README`) | |
128 | is a special case of the syntax described next: content | |
129 | recorded in the index at the given path. | |
979f7929 NTND |
130 | A path starting with './' or '../' is relative to current working directory. |
131 | The given path will be converted to be relative to working tree's root directory. | |
132 | This is most useful to address a blob or tree from a commit or tree that has | |
133 | the same tree structure with the working tree. | |
5a8f3117 MG |
134 | |
135 | * A colon, optionally followed by a stage number (0 to 3) and a | |
136 | colon, followed by a path (e.g. `:0:README`); this names a blob object in the | |
137 | index at the given path. Missing stage number (and the colon | |
138 | that follows it, e.g. `:README`) names a stage 0 entry. During a merge, stage | |
139 | 1 is the common ancestor, stage 2 is the target branch's version | |
140 | (typically the current branch), and stage 3 is the version from | |
141 | the branch being merged. | |
142 | ||
143 | Here is an illustration, by Jon Loeliger. Both commit nodes B | |
144 | and C are parents of commit node A. Parent commits are ordered | |
145 | left-to-right. | |
146 | ||
147 | ........................................ | |
148 | G H I J | |
149 | \ / \ / | |
150 | D E F | |
151 | \ | / \ | |
152 | \ | / | | |
153 | \|/ | | |
154 | B C | |
155 | \ / | |
156 | \ / | |
157 | A | |
158 | ........................................ | |
159 | ||
160 | A = = A^0 | |
161 | B = A^ = A^1 = A~1 | |
162 | C = A^2 = A^2 | |
163 | D = A^^ = A^1^1 = A~2 | |
164 | E = B^2 = A^^2 | |
165 | F = B^3 = A^^3 | |
166 | G = A^^^ = A^1^1^1 = A~3 | |
167 | H = D^2 = B^^2 = A^^^2 = A~2^2 | |
168 | I = F^ = B^3^ = A^^3^ | |
169 | J = F^2 = B^3^2 = A^^3^2 | |
170 | ||
171 | ||
172 | SPECIFYING RANGES | |
173 | ----------------- | |
174 | ||
175 | History traversing commands such as 'git log' operate on a set | |
176 | of commits, not just a single commit. To these commands, | |
177 | specifying a single revision with the notation described in the | |
178 | previous section means the set of commits reachable from that | |
179 | commit, following the commit ancestry chain. | |
180 | ||
181 | To exclude commits reachable from a commit, a prefix `{caret}` | |
182 | notation is used. E.g. `{caret}r1 r2` means commits reachable | |
183 | from `r2` but exclude the ones reachable from `r1`. | |
184 | ||
185 | This set operation appears so often that there is a shorthand | |
186 | for it. When you have two commits `r1` and `r2` (named according | |
187 | to the syntax explained in SPECIFYING REVISIONS above), you can ask | |
188 | for commits that are reachable from r2 excluding those that are reachable | |
189 | from r1 by `{caret}r1 r2` and it can be written as `r1..r2`. | |
190 | ||
191 | A similar notation `r1\...r2` is called symmetric difference | |
192 | of `r1` and `r2` and is defined as | |
193 | `r1 r2 --not $(git merge-base --all r1 r2)`. | |
194 | It is the set of commits that are reachable from either one of | |
195 | `r1` or `r2` but not from both. | |
196 | ||
197 | Two other shorthands for naming a set that is formed by a commit | |
198 | and its parent commits exist. The `r1{caret}@` notation means all | |
199 | parents of `r1`. `r1{caret}!` includes commit `r1` but excludes | |
200 | all of its parents. | |
201 | ||
202 | Here are a handful of examples: | |
203 | ||
204 | D G H D | |
205 | D F G H I J D F | |
206 | ^G D H D | |
207 | ^D B E I J F B | |
208 | B...C G H D E B C | |
209 | ^D B C E I J F B C | |
210 | C^@ I J F | |
211 | F^! D G H D F |