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-rw-r--r--Documentation/user-manual.txt25
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.