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| -rw-r--r-- | Documentation/user-manual.txt | 25 |
1 files changed, 21 insertions, 4 deletions
diff --git a/Documentation/user-manual.txt b/Documentation/user-manual.txt index 1e151b4d29..0919574fb4 100644 --- a/Documentation/user-manual.txt +++ b/Documentation/user-manual.txt @@ -437,11 +437,14 @@ We will sometimes represent git history using diagrams like the one below. Commits are shown as "o", and the links between them with lines drawn with - / and \. Time goes left to right: + +................................................ o--o--o <-- Branch A / o--o--o <-- master \ o--o--o <-- Branch B +................................................ If we need to talk about a particular commit, the character "o" may be replaced with another letter or number. @@ -1928,25 +1931,29 @@ $ git commit You have performed no merges into mywork, so it is just a simple linear sequence of patches on top of "origin": - +................................................ o--o--o <-- origin \ o--o--o <-- mywork +................................................ Some more interesting work has been done in the upstream project, and "origin" has advanced: +................................................ o--o--O--o--o--o <-- origin \ a--b--c <-- mywork +................................................ At this point, you could use "pull" to merge your changes back in; the result would create a new merge commit, like this: - +................................................ o--o--O--o--o--o <-- origin \ \ a--b--c--m <-- mywork +................................................ However, if you prefer to keep the history in mywork a simple series of commits without any merges, you may instead choose to use @@ -1963,9 +1970,11 @@ point at the latest version of origin, then apply each of the saved patches to the new mywork. The result will look like: +................................................ o--o--O--o--o--o <-- origin \ a'--b'--c' <-- mywork +................................................ In the process, it may discover conflicts. In that case it will stop and allow you to fix the conflicts; after fixing conflicts, use "git @@ -2073,24 +2082,30 @@ The primary problem with rewriting the history of a branch has to do with merging. Suppose somebody fetches your branch and merges it into their branch, with a result something like this: +................................................ o--o--O--o--o--o <-- origin \ \ t--t--t--m <-- their branch: +................................................ Then suppose you modify the last three commits: +................................................ o--o--o <-- new head of origin / o--o--O--o--o--o <-- old head of origin +................................................ If we examined all this history together in one repository, it will look like: +................................................ o--o--o <-- new head of origin / o--o--O--o--o--o <-- old head of origin \ \ t--t--t--m <-- their branch: +................................................ Git has no way of knowing that the new head is an updated version of the old head; it treats this situation exactly the same as it would if @@ -2151,9 +2166,11 @@ commit. Git calls this process a "fast forward". A fast forward looks something like this: +................................................ o--o--o--o <-- old head of the branch \ o--o--o <-- new head of the branch +................................................ In some cases it is possible that the new head will *not* actually be @@ -2161,11 +2178,11 @@ a descendant of the old head. For example, the developer may have realized she made a serious mistake, and decided to backtrack, resulting in a situation like: +................................................ o--o--o--o--a--b <-- old head of the branch \ o--o--o <-- new head of the branch - - +................................................ In this case, "git fetch" will fail, and print out a warning. |