Mostly making the formatted html prettier.
Signed-off-by: Junio C Hamano <junkio@cox.net>
(cherry picked from 7adf1f15ebe074d4767df941817a6cf86d8e2533 commit)
@ -22,8 +22,8 @@ The git-diff-* family works by first comparing two sets of
@@ -22,8 +22,8 @@ The git-diff-* family works by first comparing two sets of
files:
- git-diff-cache compares contents of a "tree" object and the
working directory (when --cached flag is not used) or a
"tree" object and the index file (when --cached flag is
working directory (when '--cached' flag is not used) or a
"tree" object and the index file (when '--cached' flag is
used);
- git-diff-files compares contents of the index file and the
@ -37,29 +37,31 @@ comparison is passed from these commands to what is internally
@@ -37,29 +37,31 @@ comparison is passed from these commands to what is internally
called "diffcore", in a format similar to what is output when
the -p option is not used. E.g.
in-place edit :100644 100644 bcd1234... 0123456... M file0
create :000000 100644 0000000... 1234567... N file4
delete :100644 000000 1234567... 0000000... D file5
unmerged :000000 000000 0000000... 0000000... U file6
------------------------------------------------
in-place edit :100644 100644 bcd1234... 0123456... M file0
create :000000 100644 0000000... 1234567... A file4
delete :100644 000000 1234567... 0000000... D file5
unmerged :000000 000000 0000000... 0000000... U file6
------------------------------------------------
The diffcore mechanism is fed a list of such comparison results
(each of which is called "filepair", although at this point each
of them talks about a single file), and transforms such a list
into another list. There are currently 6 such transformations:
- diffcore-pathspec
- diffcore-break
- diffcore-rename
- diffcore-merge-broken
- diffcore-pickaxe
- diffcore-order
- diffcore-pathspec
- diffcore-break
- diffcore-rename
- diffcore-merge-broken
- diffcore-pickaxe
- diffcore-order
These are applied in sequence. The set of filepairs git-diff-*
These are applied in sequence. The set of filepairs git-diff-\*
commands find are used as the input to diffcore-pathspec, and
the output from diffcore-pathspec is used as the input to the
next transformation. The final result is then passed to the
output routine and generates either diff-raw format (see Output
format sections of the manual for git-diff-* commands) or
format sections of the manual for git-diff-\* commands) or
diff-patch format.
@ -87,13 +89,17 @@ used to detect a filepair that represents "complete rewrite" and
@@ -87,13 +89,17 @@ used to detect a filepair that represents "complete rewrite" and
break such filepair into two filepairs that represent delete and
create. E.g. If the input contained this filepair:
:100644 100644 bcd1234... 0123456... M file0
------------------------------------------------
:100644 100644 bcd1234... 0123456... M file0
------------------------------------------------
and if it detects that the file "file0" is completely rewritten,
it changes it to:
:100644 000000 bcd1234... 0000000... D file0
:000000 100644 0000000... 0123456... N file0
------------------------------------------------
:100644 000000 bcd1234... 0000000... D file0
:000000 100644 0000000... 0123456... A file0
------------------------------------------------
For the purpose of breaking a filepair, diffcore-break examines
the extent of changes between the contents of the files before
@ -117,14 +123,18 @@ controlled by the -M option (to detect renames) and the -C option
@@ -117,14 +123,18 @@ controlled by the -M option (to detect renames) and the -C option
(to detect copies as well) to the git-diff-* commands. If the
input contained these filepairs:
:100644 000000 0123456... 0000000... D fileX
:000000 100644 0000000... 0123456... N file0
------------------------------------------------
:100644 000000 0123456... 0000000... D fileX
:000000 100644 0000000... 0123456... A file0
------------------------------------------------
and the contents of the deleted file fileX is similar enough to
the contents of the created file file0, then rename detection
When the "-C" option is used, the original contents of modified
files and contents of unchanged files are considered as
@ -133,15 +143,19 @@ addition to the deleted files. If the input were like these
@@ -133,15 +143,19 @@ addition to the deleted files. If the input were like these
filepairs, that talk about a modified file fileY and a newly
created file file0:
:100644 100644 0123456... 1234567... M fileY
:000000 100644 0000000... 0123456... N file0
------------------------------------------------
:100644 100644 0123456... 1234567... M fileY
:000000 100644 0000000... 0123456... A file0
------------------------------------------------
the original contents of fileY and the resulting contents of
file0 are compared, and if they are similar enough, they are
In both rename and copy detection, the same "extent of changes"
algorithm used in diffcore-break is used to determine if two
@ -151,11 +165,11 @@ number after "-M" or "-C" option (e.g. "-M8" to tell it to use
@@ -151,11 +165,11 @@ number after "-M" or "-C" option (e.g. "-M8" to tell it to use
8/10 = 80%).
Note. When the "-C" option is used with --find-copies-harder
option, git-diff-* commands feed unmodified filepairs to
option, git-diff-\* commands feed unmodified filepairs to
diffcore mechanism as well as modified ones. This lets the copy
detector consider unmodified files as copy source candidates at
the expense of making it slower. Without --find-copies-harder,
git-diff-* commands can detect copies only if the file that was
git-diff-\* commands can detect copies only if the file that was
copied happened to have been modified in the same changeset.
@ -186,10 +200,10 @@ material is deleted, the broken pairs are merged back into a
@@ -186,10 +200,10 @@ material is deleted, the broken pairs are merged back into a
single modification) by giving a second number to -B option,
like these:
-B50/60 (give 50% "break score" to diffcore-break, use
60% for diffcore-merge-broken).
-B/60 (the same as above, since diffcore-break defautls to
50%).
* -B50/60 (give 50% "break score" to diffcore-break, use 60%
for diffcore-merge-broken).
* -B/60 (the same as above, since diffcore-break defaults to 50%).
Note that earlier implementation left a broken pair as a separate
creation and deletion patches. This was unnecessary hack and
@ -237,12 +251,14 @@ in the file are output before ones that match a later line, and
@@ -237,12 +251,14 @@ in the file are output before ones that match a later line, and
filepairs that do not match any glob pattern are output last.
As an example, typical orderfile for the core GIT probably
@ -67,6 +69,12 @@ branches ("git bisect start" will do that for you too, actually: it will
@@ -67,6 +69,12 @@ branches ("git bisect start" will do that for you too, actually: it will
reset the bisection state, and before it does that it checks that you're
not using some old bisection branch).
During the bisection process, you can say
git bisect visualize
to see the currently remaining suspects in `gitk`.
@ -19,11 +19,14 @@ This is reference information for the core git commands.
@@ -19,11 +19,14 @@ This is reference information for the core git commands.
Before reading this cover to cover, you may want to take a look
at the link:tutorial.html[tutorial] document.
The Discussion section below contains much useful definition and
The <<Discussion>> section below contains much useful definition and
clarification info - read that first. And of the commands, I suggest
reading link:git-update-cache.html[git-update-cache] and
link:git-read-tree.html[git-read-tree] first - I wish I had!
If you are migrating from CVS, link:cvs-migration.html[cvs migration]
document may be helpful after you finish the tutorial.
After you get the general feel from the tutorial and this
@ -32,13 +32,15 @@ one for a totally new project, or an existing working tree that you want
@@ -32,13 +32,15 @@ one for a totally new project, or an existing working tree that you want
to import into git.
For our first example, we're going to start a totally new repository from
scratch, with no pre-existing files, and we'll call it "git-tutorial".
scratch, with no pre-existing files, and we'll call it `git-tutorial`.
To start up, create a subdirectory for it, change into that
subdirectory, and initialize the git infrastructure with "git-init-db":
subdirectory, and initialize the git infrastructure with `git-init-db`:
mkdir git-tutorial
cd git-tutorial
git-init-db
------------------------------------------------
mkdir git-tutorial
cd git-tutorial
git-init-db
------------------------------------------------
to which git will reply
@ -46,48 +48,50 @@ to which git will reply
@@ -46,48 +48,50 @@ to which git will reply
which is just git's way of saying that you haven't been doing anything
strange, and that it will have created a local .git directory setup for
your new project. You will now have a ".git" directory, and you can
inspect that with "ls". For your new empty project, ls should show you
your new project. You will now have a `.git` directory, and you can
inspect that with `ls`. For your new empty project, it should show you
three entries, among other things:
- a symlink called HEAD, pointing to "refs/heads/master"
Don't worry about the fact that the file that the HEAD link points to
doesn't even exist yet - you haven't created the commit that will
start your HEAD development branch yet.
- a symlink called `HEAD`, pointing to `refs/heads/master`
+
Don't worry about the fact that the file that the `HEAD` link points to
doesn't even exist yet - you haven't created the commit that will
start your `HEAD` development branch yet.
- a subdirectory called "objects", which will contain all the
- a subdirectory called `objects`, which will contain all the
objects of your project. You should never have any real reason to
look at the objects directly, but you might want to know that these
objects are what contains all the real _data_ in your repository.
- a subdirectory called "refs", which contains references to objects.
In particular, the "refs" subdirectory will contain two other
subdirectories, named "heads" and "tags" respectively. They do
exactly what their names imply: they contain references to any number
of different "heads" of development (aka "branches"), and to any
"tags" that you have created to name specific versions in your
repository.
One note: the special "master" head is the default branch, which is
why the .git/HEAD file was created as a symlink to it even if it
doesn't yet exist. Basically, the HEAD link is supposed to always
point to the branch you are working on right now, and you always
start out expecting to work on the "master" branch.
However, this is only a convention, and you can name your branches
anything you want, and don't have to ever even _have_ a "master"
branch. A number of the git tools will assume that .git/HEAD is
valid, though.
[ Implementation note: an "object" is identified by its 160-bit SHA1
hash, aka "name", and a reference to an object is always the 40-byte
hex representation of that SHA1 name. The files in the "refs"
subdirectory are expected to contain these hex references (usually
with a final '\n' at the end), and you should thus expect to see a
number of 41-byte files containing these references in this refs
subdirectories when you actually start populating your tree ]
objects are what contains all the real 'data' in your repository.
- a subdirectory called `refs`, which contains references to objects.
In particular, the `refs` subdirectory will contain two other
subdirectories, named `heads` and `tags` respectively. They do
exactly what their names imply: they contain references to any number
of different 'heads' of development (aka 'branches'), and to any
'tags' that you have created to name specific versions in your
repository.
One note: the special `master` head is the default branch, which is
why the `.git/HEAD` file was created as a symlink to it even if it
doesn't yet exist. Basically, the `HEAD` link is supposed to always
point to the branch you are working on right now, and you always
start out expecting to work on the `master` branch.
However, this is only a convention, and you can name your branches
anything you want, and don't have to ever even 'have' a `master`
branch. A number of the git tools will assume that `.git/HEAD` is
valid, though.
[NOTE]
An "object" is identified by its 160-bit SHA1 hash, aka "name",
and a reference to an object is always the 40-byte hex
representation of that SHA1 name. The files in the "refs"
subdirectory are expected to contain these hex references
(usually with a final '\n' at the end), and you should thus
expect to see a number of 41-byte files containing these
references in this refs subdirectories when you actually start
populating your tree.
You have now created your first git repository. Of course, since it's
empty, that's not very useful, so let's start populating it with data.
@ -103,8 +107,10 @@ Start off with just creating any random files that you want to maintain
@@ -103,8 +107,10 @@ Start off with just creating any random files that you want to maintain
in your git repository. We'll start off with a few bad examples, just to
get a feel for how this works:
echo "Hello World" >hello
echo "Silly example" >example
------------------------------------------------
echo "Hello World" >hello
echo "Silly example" >example
------------------------------------------------
you have now created two files in your working tree (aka "working directory"), but to
actually check in your hard work, you will have to go through two steps:
@ -115,16 +121,18 @@ actually check in your hard work, you will have to go through two steps:
@@ -115,16 +121,18 @@ actually check in your hard work, you will have to go through two steps:
- commit that index file as an object.
The first step is trivial: when you want to tell git about any changes
to your working tree, you use the "git-update-cache" program. That
to your working tree, you use the `git-update-cache` program. That
program normally just takes a list of filenames you want to update, but
to avoid trivial mistakes, it refuses to add new entries to the cache
(or remove existing ones) unless you explicitly tell it that you're
adding a new entry with the "--add" flag (or removing an entry with the
"--remove") flag.
adding a new entry with the `--add` flag (or removing an entry with the
`--remove`) flag.
So to populate the index with the two files you just created, you can do
git-update-cache --add hello example
------------------------------------------------
git-update-cache --add hello example
------------------------------------------------
and you have now told git to track those two files.
@ -156,23 +164,25 @@ regular file), and you can see the contents with
@@ -156,23 +164,25 @@ regular file), and you can see the contents with
which will print out "Hello World". The object 557db03 is nothing
more than the contents of your file "hello".
[ Digression: don't confuse that object with the file "hello" itself. The
object is literally just those specific _contents_ of the file, and
however much you later change the contents in file "hello", the object we
just looked at will never change. Objects are immutable. ]
[NOTE]
Don't confuse that object with the file "hello" itself. The
object is literally just those specific _contents_ of the file, and
however much you later change the contents in file "hello", the object we
just looked at will never change. Objects are immutable.
[ Digression #2: the second example demonstrates that you can
abbreviate the object name to only the first several
hexadecimal digits in most places. ]
[NOTE]
The second example demonstrates that you can
abbreviate the object name to only the first several
hexadecimal digits in most places.
Anyway, as we mentioned previously, you normally never actually take a
look at the objects themselves, and typing long 40-character hex
names is not something you'd normally want to do. The above digression
was just to show that "git-update-cache" did something magical, and
was just to show that `git-update-cache` did something magical, and
actually saved away the contents of your files into the git object
database.
Updating the cache did something else too: it created a ".git/index"
Updating the cache did something else too: it created a `.git/index`
file. This is the index that describes your current working tree, and
something you should be very aware of. Again, you normally never worry
about the index file itself, but you should be aware of the fact that
@ -185,7 +195,9 @@ most basic git commands to manipulate the files or look at their status.
@@ -185,7 +195,9 @@ most basic git commands to manipulate the files or look at their status.
In particular, let's not even check in the two files into git yet, we'll
start off by adding another line to "hello" first:
echo "It's a new day for git" >>hello
------------------------------------------------
echo "It's a new day for git" >>hello
------------------------------------------------
and you can now, since you told git about the previous state of "hello", ask
git what has changed in the tree compared to your old index, using the
@ -241,7 +253,9 @@ index. In other words, we're now tying together all the different
@@ -241,7 +253,9 @@ index. In other words, we're now tying together all the different
filenames with their contents (and their permissions), and we're
creating the equivalent of a git "directory" object:
git-write-tree
------------------------------------------------
git-write-tree
------------------------------------------------
and this will just output the name of the resulting tree, in this case
(if you have done exactly as I've described) it should be
@ -272,7 +286,9 @@ supposed to contain the reference to the top-of-tree, and since that's
@@ -272,7 +286,9 @@ supposed to contain the reference to the top-of-tree, and since that's
exactly what git-commit-tree spits out, we can do this all with a simple
@ -344,19 +360,20 @@ current working tree state entirely. Since we just wrote the index
@@ -344,19 +360,20 @@ current working tree state entirely. Since we just wrote the index
file to HEAD, doing "git-diff-cache --cached -p HEAD" should thus return
an empty set of differences, and that's exactly what it does.
[ Digression: "git-diff-cache" really always uses the index for its
comparisons, and saying that it compares a tree against the working
tree is thus not strictly accurate. In particular, the list of
files to compare (the "meta-data") _always_ comes from the index file,
regardless of whether the --cached flag is used or not. The --cached
flag really only determines whether the file _contents_ to be compared
come from the working tree or not.
This is not hard to understand, as soon as you realize that git simply
never knows (or cares) about files that it is not told about
explicitly. Git will never go _looking_ for files to compare, it
expects you to tell it what the files are, and that's what the index
is there for. ]
[NOTE]
"git-diff-cache" really always uses the index for its
comparisons, and saying that it compares a tree against the working
tree is thus not strictly accurate. In particular, the list of
files to compare (the "meta-data") _always_ comes from the index file,
regardless of whether the --cached flag is used or not. The --cached
flag really only determines whether the file _contents_ to be compared
come from the working tree or not.
+
This is not hard to understand, as soon as you realize that git simply
never knows (or cares) about files that it is not told about
explicitly. Git will never go _looking_ for files to compare, it
expects you to tell it what the files are, and that's what the index
is there for.
However, our next step is to commit the _change_ we did, and again, to
understand what's going on, keep in mind the difference between "working
@ -365,7 +382,9 @@ in the working tree that we want to commit, and we always have to
@@ -365,7 +382,9 @@ in the working tree that we want to commit, and we always have to
work through the index file, so the first thing we need to do is to
update the index cache:
git-update-cache hello
------------------------------------------------
git-update-cache hello
------------------------------------------------
(note how we didn't need the "--add" flag this time, since git knew
about the file already).
@ -384,7 +403,9 @@ tell commit that the HEAD was the _parent_ of the new commit, and that
@@ -384,7 +403,9 @@ tell commit that the HEAD was the _parent_ of the new commit, and that
this wasn't an initial commit any more), but you've done that once
already, so let's just use the helpful script this time:
git commit
------------------------------------------------
git commit
------------------------------------------------
which starts an editor for you to write the commit message and tells you
and you will see exactly what has changed in the repository over its
short history.
[ Side note: the "--root" flag is a flag to git-diff-tree to tell it to
show the initial aka "root" commit too. Normally you'd probably not
want to see the initial import diff, but since the tutorial project
was started from scratch and is so small, we use it to make the result
a bit more interesting. ]
[NOTE]
The "--root" flag is a flag to git-diff-tree to tell it to
show the initial aka "root" commit too. Normally you'd probably not
want to see the initial import diff, but since the tutorial project
was started from scratch and is so small, we use it to make the result
a bit more interesting.
With that, you should now be having some inkling of what git does, and
can explore on your own.
[ Side note: most likely, you are not directly using the core
git Plumbing commands, but using Porcelain like Cogito on top
of it. Cogito works a bit differently and you usually do not
have to run "git-update-cache" yourself for changed files (you
do tell underlying git about additions and removals via
"cg-add" and "cg-rm" commands). Just before you make a commit
with "cg-commit", Cogito figures out which files you modified,
and runs "git-update-cache" on them for you. ]
[NOTE]
Most likely, you are not directly using the core
git Plumbing commands, but using Porcelain like Cogito on top
of it. Cogito works a bit differently and you usually do not
have to run "git-update-cache" yourself for changed files (you
do tell underlying git about additions and removals via
"cg-add" and "cg-rm" commands). Just before you make a commit
with "cg-commit", Cogito figures out which files you modified,
and runs "git-update-cache" on them for you.
Tagging a version
@ -474,7 +497,9 @@ A "light" tag is technically nothing more than a branch, except we put
@@ -474,7 +497,9 @@ A "light" tag is technically nothing more than a branch, except we put
it in the ".git/refs/tags/" subdirectory instead of calling it a "head".
So the simplest form of tag involves nothing more than
git tag my-first-tag
------------------------------------------------
git tag my-first-tag
------------------------------------------------
which just writes the current HEAD into the .git/refs/tags/my-first-tag
file, after which point you can then use this symbolic name for that
@ -514,12 +539,13 @@ that unlike CVS, for example, there is no separate notion of
@@ -514,12 +539,13 @@ that unlike CVS, for example, there is no separate notion of
working tree, with the local git information hidden in the ".git"
subdirectory. There is nothing else. What you see is what you got.
[ Side note: you can tell git to split the git internal information from
the directory that it tracks, but we'll ignore that for now: it's not
how normal projects work, and it's really only meant for special uses.
So the mental model of "the git information is always tied directly to
the working tree that it describes" may not be technically 100%
accurate, but it's a good model for all normal use ]
[NOTE]
You can tell git to split the git internal information from
the directory that it tracks, but we'll ignore that for now: it's not
how normal projects work, and it's really only meant for special uses.
So the mental model of "the git information is always tied directly to
the working tree that it describes" may not be technically 100%
accurate, but it's a good model for all normal use.
This has two implications:
@ -527,24 +553,24 @@ This has two implications:
@@ -527,24 +553,24 @@ This has two implications:
made a mistake and want to start all over), you can just do simple
rm -rf git-tutorial
and it will be gone. There's no external repository, and there's no
history outside the project you created.
+
and it will be gone. There's no external repository, and there's no
history outside the project you created.
- if you want to move or duplicate a git repository, you can do so. There
is "git clone" command, but if all you want to do is just to
create a copy of your repository (with all the full history that
went along with it), you can do so with a regular
"cp -a git-tutorial new-git-tutorial".
Note that when you've moved or copied a git repository, your git index
file (which caches various information, notably some of the "stat"
information for the files involved) will likely need to be refreshed.
So after you do a "cp -a" to create a new copy, you'll want to do
+
Note that when you've moved or copied a git repository, your git index
file (which caches various information, notably some of the "stat"
information for the files involved) will likely need to be refreshed.
So after you do a "cp -a" to create a new copy, you'll want to do
git-update-cache --refresh
in the new repository to make sure that the index file is up-to-date.
+
in the new repository to make sure that the index file is up-to-date.
Note that the second point is true even across machines. You can
duplicate a remote git repository with _any_ regular copy mechanism, be it
@ -572,15 +598,15 @@ The above can also be written as simply
@@ -572,15 +598,15 @@ The above can also be written as simply
and in fact a lot of the common git command combinations can be scripted
with the "git xyz" interfaces, and you can learn things by just looking
at what the git-*-script scripts do ("git reset" is the above two lines
implemented in "git-reset-script", but some things like "git status" and
"git commit" are slightly more complex scripts around the basic git
at what the `git-*-script` scripts do (`git reset` is the above two lines
implemented in `git-reset-script`, but some things like "git status" and
`git commit` are slightly more complex scripts around the basic git
commands).
Many (most?) public remote repositories will not contain any of
the checked out files or even an index file, and will _only_ contain the
the checked out files or even an index file, and will 'only' contain the
actual core git files. Such a repository usually doesn't even have the
".git" subdirectory, but has all the git files directly in the
`.git` subdirectory, but has all the git files directly in the
repository.
To create your own local live copy of such a "raw" git repository, you'd
@ -641,20 +667,25 @@ To show that as an example, let's go back to the git-tutorial repository we
@@ -641,20 +667,25 @@ To show that as an example, let's go back to the git-tutorial repository we
used earlier, and create a branch in it. You do that by simply just
saying that you want to check out a new branch:
git checkout -b mybranch
------------
git checkout -b mybranch
------------
will create a new branch based at the current HEAD position, and switch
to it.
[ Side note: if you make the decision to start your new branch at some
other point in the history than the current HEAD, you can do so by
just telling "git checkout" what the base of the checkout would be.
In other words, if you have an earlier tag or branch, you'd just do
[NOTE]
================================================
If you make the decision to start your new branch at some
other point in the history than the current HEAD, you can do so by
just telling "git checkout" what the base of the checkout would be.
In other words, if you have an earlier tag or branch, you'd just do
git checkout -b mybranch earlier-commit
and it would create the new branch "mybranch" at the earlier commit,
and check out the state at that time. ]
and it would create the new branch "mybranch" at the earlier commit,
and check out the state at that time.
================================================
You can always just jump back to your original "master" branch by doing
@ -670,7 +701,7 @@ you have, you can say
@@ -670,7 +701,7 @@ you have, you can say
git branch
which is nothing more than a simple script around "ls .git/refs/heads".
which is nothing more than a simple script around `ls .git/refs/heads`.
There will be asterisk in front of the branch you are currently on.
Sometimes you may wish to create a new branch _without_ actually
@ -693,9 +724,11 @@ branch. So assuming you created the above "mybranch" that started out
@@ -693,9 +724,11 @@ branch. So assuming you created the above "mybranch" that started out
being the same as the original "master" branch, let's make sure we're in
that branch, and do some work there.
git checkout mybranch
echo "Work, work, work" >>hello
git commit -m 'Some work.' hello
------------
git checkout mybranch
echo "Work, work, work" >>hello
git commit -m 'Some work.' hello
------------
Here, we just added another line to "hello", and we used a shorthand for
both going a "git-update-cache hello" and "git commit" by just giving the
@ -706,15 +739,19 @@ Now, to make it a bit more interesting, let's assume that somebody else
@@ -706,15 +739,19 @@ Now, to make it a bit more interesting, let's assume that somebody else
does some work in the original branch, and simulate that by going back
to the master branch, and editing the same file differently there:
git checkout master
------------
git checkout master
------------
Here, take a moment to look at the contents of "hello", and notice how they
don't contain the work we just did in "mybranch" - because that work
hasn't happened in the "master" branch at all. Then do
echo "Play, play, play" >>hello
echo "Lots of fun" >>example
git commit -m 'Some fun.' hello example
------------
echo "Play, play, play" >>hello
echo "Lots of fun" >>example
git commit -m 'Some fun.' hello example
------------
since the master branch is obviously in a much better mood.
@ -735,7 +772,9 @@ branch (which is currently our HEAD too). To do that, there's a nice
@@ -735,7 +772,9 @@ branch (which is currently our HEAD too). To do that, there's a nice
script called "git resolve", which wants to know which branches you want
to resolve and what the merge is all about:
git resolve HEAD mybranch "Merge work in mybranch"
------------
git resolve HEAD mybranch "Merge work in mybranch"
------------
where the third argument is going to be used as the commit message if
the merge can be resolved automatically.
@ -761,14 +800,18 @@ should already be well used to if you've ever used CVS, so let's just
@@ -761,14 +800,18 @@ should already be well used to if you've ever used CVS, so let's just
open "hello" in our editor (whatever that may be), and fix it up somehow.
I'd suggest just making it so that "hello" contains all four lines:
Hello World
It's a new day for git
Play, play, play
Work, work, work
------------
Hello World
It's a new day for git
Play, play, play
Work, work, work
------------
and once you're happy with your manual merge, just do a
git commit hello
------------
git commit hello
------------
which will very loudly warn you that you're now committing a merge
(which is correct, so never mind), and you can write a small merge
@ -781,8 +824,8 @@ switch to it, and continue to work with it if you want to. The
@@ -781,8 +824,8 @@ switch to it, and continue to work with it if you want to. The
from the "master" branch, git will know how you merged it, so you'll not
have to do _that_ merge again.
Another useful tool, especially if you do not work in X-Window
environment all the time, is "git show-branch".
Another useful tool, especially if you do not always work in X-Window
@ -944,8 +989,9 @@ changes you made in your primary working tree are in good shape,
@@ -944,8 +989,9 @@ changes you made in your primary working tree are in good shape,
update the public repository from it. This is often called
"pushing".
[ Side note: this public repository could further be mirrored,
and that is how kernel.org git repositories are done. ]
[NOTE]
This public repository could further be mirrored,
and that is how kernel.org git repositories are done.
Publishing the changes from your local (private) repository to
your remote (public) repository requires a write privilege on
@ -958,10 +1004,11 @@ repository will be populated and be kept up-to-date by pushing
@@ -958,10 +1004,11 @@ repository will be populated and be kept up-to-date by pushing
into it later. Obviously, this repository creation needs to be
done only once.
[ Digression: "git push" uses a pair of programs,
"git-send-pack" on your local machine, and "git-receive-pack"
on the remote machine. The communication between the two over
the network internally uses an SSH connection. ]
[NOTE]
"git push" uses a pair of programs,
"git-send-pack" on your local machine, and "git-receive-pack"
on the remote machine. The communication between the two over
the network internally uses an SSH connection.
Your private repository's GIT directory is usually .git, but
your public repository is often named after the project name,
@ -982,12 +1029,13 @@ changes to be pulled by via the transport of your choice. Also
@@ -982,12 +1029,13 @@ changes to be pulled by via the transport of your choice. Also
you need to make sure that you have the "git-receive-pack"
program on the $PATH.
[ Side note: many installations of sshd do not invoke your shell
as the login shell when you directly run programs; what this
means is that if your login shell is bash, only .bashrc is
read and not .bash_profile. As a workaround, make sure
.bashrc sets up $PATH so that you can run 'git-receive-pack'
program. ]
[NOTE]
Many installations of sshd do not invoke your shell
as the login shell when you directly run programs; what this
means is that if your login shell is bash, only .bashrc is
read and not .bash_profile. As a workaround, make
sure .bashrc sets up $PATH so that you can run 'git-receive-pack'
program.
Your "public repository" is now ready to accept your changes.
Come back to the machine you have your private repository. From
@ -1024,13 +1072,14 @@ directories by now. "git repack" tells you how many objects it
@@ -1024,13 +1072,14 @@ directories by now. "git repack" tells you how many objects it
packed, and stores the packed file in .git/objects/pack
directory.
[ Side Note: you will see two files, pack-*.pack and pack-*.idx,
in .git/objects/pack directory. They are closely related to
each other, and if you ever copy them by hand to a different
repository for whatever reason, you should make sure you copy
them together. The former holds all the data from the objects
in the pack, and the latter holds the index for random
access. ]
[NOTE]
You will see two files, pack-\*.pack and pack-\*.idx,
in .git/objects/pack directory. They are closely related to
each other, and if you ever copy them by hand to a different
repository for whatever reason, you should make sure you copy
them together. The former holds all the data from the objects
in the pack, and the latter holds the index for random
access.
If you are paranoid, running "git-verify-pack" command would
detect if you have a corrupt pack, but do not worry too much.
@ -1046,11 +1095,12 @@ would remove them for you.
@@ -1046,11 +1095,12 @@ would remove them for you.
You can try running "find .git/objects -type f" before and after
you run "git prune-packed" if you are curious.
[ Side Note: "git pull" is slightly cumbersome for HTTP transport,
as a packed repository may contain relatively few objects in a
relatively large pack. If you expect many HTTP pulls from your
public repository you might want to repack & prune often, or
never. ]
[NOTE]
"git pull" is slightly cumbersome for HTTP transport,
as a packed repository may contain relatively few objects in a
relatively large pack. If you expect many HTTP pulls from your
public repository you might want to repack & prune often, or
never.
If you run "git repack" again at this point, it will say
"Nothing to pack". Once you continue your development and
@ -1083,93 +1133,92 @@ from only one remote repository.
@@ -1083,93 +1133,92 @@ from only one remote repository.
A recommended workflow for a "project lead" goes like this:
(1) Prepare your primary repository on your local machine. Your
work is done there.
1. Prepare your primary repository on your local machine. Your
work is done there.
(2) Prepare a public repository accessible to others.
2. Prepare a public repository accessible to others.
(3) Push into the public repository from your primary
repository.
3. Push into the public repository from your primary
repository.
(4) "git repack" the public repository. This establishes a big
pack that contains the initial set of objects as the
baseline, and possibly "git prune-packed" if the transport
used for pulling from your repository supports packed
repositories.
4. "git repack" the public repository. This establishes a big
pack that contains the initial set of objects as the
baseline, and possibly "git prune-packed" if the transport
used for pulling from your repository supports packed
repositories.
(5) Keep working in your primary repository. Your changes
include modifications of your own, patches you receive via
e-mails, and merges resulting from pulling the "public"
repositories of your "subsystem maintainers".
5. Keep working in your primary repository. Your changes
include modifications of your own, patches you receive via
e-mails, and merges resulting from pulling the "public"
repositories of your "subsystem maintainers".
+
You can repack this private repository whenever you feel like.
You can repack this private repository whenever you feel
like.
6. Push your changes to the public repository, and announce it
to the public.
(6) Push your changes to the public repository, and announce it
to the public.
(7) Every once in a while, "git repack" the public repository.
Go back to step (5) and continue working.
7. Every once in a while, "git repack" the public repository.
Go back to step 5. and continue working.
A recommended work cycle for a "subsystem maintainer" who works
on that project and has an own "public repository" goes like this:
(1) Prepare your work repository, by "git clone" the public
repository of the "project lead". The URL used for the
initial cloning is stored in .git/branches/origin.
(2) Prepare a public repository accessible to others.
1. Prepare your work repository, by "git clone" the public
repository of the "project lead". The URL used for the
initial cloning is stored in .git/branches/origin.
(3) Copy over the packed files from "project lead" public
repository to your public repository by hand; preferrably
use rsync for that task.
2. Prepare a public repository accessible to others.
(4) Push into the public repository from your primary
repository. Run "git repack", and possibly "git
prune-packed" if the transport used for pulling from your
repository supports packed repositories.
3. Copy over the packed files from "project lead" public
repository to your public repository by hand; preferrably
use rsync for that task.
(5) Keep working in your primary repository. Your changes
include modifications of your own, patches you receive via
e-mails, and merges resulting from pulling the "public"
repositories of your "project lead" and possibly your
"sub-subsystem maintainers".
4. Push into the public repository from your primary
repository. Run "git repack", and possibly "git
prune-packed" if the transport used for pulling from your
repository supports packed repositories.
You can repack this private repository whenever you feel
like.
5. Keep working in your primary repository. Your changes
include modifications of your own, patches you receive via
e-mails, and merges resulting from pulling the "public"
repositories of your "project lead" and possibly your
"sub-subsystem maintainers".
+
You can repack this private repository whenever you feel
like.
(6) Push your changes to your public repository, and ask your
"project lead" and possibly your "sub-subsystem
maintainers" to pull from it.
6. Push your changes to your public repository, and ask your
"project lead" and possibly your "sub-subsystem
maintainers" to pull from it.
(7) Every once in a while, "git repack" the public repository.
Go back to step (5) and continue working.
7. Every once in a while, "git repack" the public repository.
Go back to step 5. and continue working.
A recommended work cycle for an "individual developer" who does
not have a "public" repository is somewhat different. It goes
like this:
(1) Prepare your work repository, by "git clone" the public
repository of the "project lead" (or a "subsystem
maintainer", if you work on a subsystem). The URL used for
the initial cloning is stored in .git/branches/origin.
1. Prepare your work repository, by "git clone" the public
repository of the "project lead" (or a "subsystem
maintainer", if you work on a subsystem). The URL used for
the initial cloning is stored in .git/branches/origin.
(2) Do your work there. Make commits.
2. Do your work there. Make commits.
(3) Run "git fetch origin" from the public repository of your
upstream every once in a while. This does only the first
half of "git pull" but does not merge. The head of the
public repository is stored in .git/refs/heads/origin.
3. Run "git fetch origin" from the public repository of your
upstream every once in a while. This does only the first
half of "git pull" but does not merge. The head of the
public repository is stored in .git/refs/heads/origin.
(4) Use "git cherry origin" to see which ones of your patches
were accepted, and/or use "git rebase origin" to port your
unmerged changes forward to the updated upstream.
4. Use "git cherry origin" to see which ones of your patches
were accepted, and/or use "git rebase origin" to port your
unmerged changes forward to the updated upstream.
(5) Use "git format-patch origin" to prepare patches for e-mail
submission to your upstream and send it out. Go back to
step (2) and continue.
5. Use "git format-patch origin" to prepare patches for e-mail
submission to your upstream and send it out. Go back to
- "goddamn idiotic truckload of sh*t": when it breaks
This is a stupid (but extremely fast) directory content manager. It
doesn't do a whole lot, but what it _does_ do is track directory
doesn't do a whole lot, but what it 'does' do is track directory
contents efficiently.
There are two object abstractions: the "object database", and the
@ -66,9 +66,11 @@ Regardless of object type, all objects share the following
@@ -66,9 +66,11 @@ Regardless of object type, all objects share the following
characteristics: they are all deflated with zlib, and have a header
that not only specifies their tag, but also provides size information
about the data in the object. It's worth noting that the SHA1 hash
that is used to name the object is the hash of the original data.
that is used to name the object is the hash of the original data
plus this header, so `sha1sum` 'file' does not match the object name
for 'file'.
(Historical note: in the dawn of the age of git the hash
was the sha1 of the _compressed_ object)
was the sha1 of the 'compressed' object.)
As a result, the general consistency of an object can always be tested
independently of the contents or the type of the object: all objects can
A "blob" object is nothing but a binary blob of data, and doesn't
refer to anything else. There is no signature or any other
verification of the data, so while the object is consistent (it _is_
verification of the data, so while the object is consistent (it 'is'
indexed by its sha1 hash, so the data itself is certainly correct), it
has absolutely no other attributes. No name associations, no
permissions. It is purely a blob of data (i.e. normally "file
@ -125,7 +127,7 @@ trust that the tree is immutable and its contents never change.
@@ -125,7 +127,7 @@ trust that the tree is immutable and its contents never change.
So you can trust the contents of a tree to be valid, the same way you
can trust the contents of a blob, but you don't know where those
contents _came_ from.
contents 'came' from.
Side note on trees: since a "tree" object is a sorted list of
"filename+content", you can create a diff between two trees without
@ -142,7 +144,8 @@ noticing that the blob stayed the same. However, renames with data
@@ -142,7 +144,8 @@ noticing that the blob stayed the same. However, renames with data
changes need a smarter "diff" implementation.
A tree is created with link:git-write-tree.html[git-write-tree] and
its data can be accessed by link:git-ls-tree.html[git-ls-tree]
its data can be accessed by link:git-ls-tree.html[git-ls-tree].
Two trees can be compared with link:git-diff-tree.html[git-diff-tree].
Commit Object
~~~~~~~~~~~~~
@ -161,19 +164,19 @@ The parents do not have to actually have any relationship with the
@@ -161,19 +164,19 @@ The parents do not have to actually have any relationship with the
result, for example.
Note on commits: unlike real SCM's, commits do not contain
rename information or file mode chane information. All of that is
rename information or file mode change information. All of that is
implicit in the trees involved (the result tree, and the result trees
of the parents), and describing that makes no sense in this idiotic
file manager.
A commit is created with link:git-commit-tree.html[git-commit-tree] and
its data can be accessed by link:git-cat-file.html[git-cat-file]
its data can be accessed by link:git-cat-file.html[git-cat-file].
Trust
~~~~~
An aside on the notion of "trust". Trust is really outside the scope
of "git", but it's worth noting a few things. First off, since
everything is hashed with SHA1, you _can_ trust that an object is
everything is hashed with SHA1, you 'can' trust that an object is
intact and has not been messed with by external sources. So the name
of an object uniquely identifies a known state - just not a state that
you may want to trust.
@ -185,7 +188,7 @@ of history, with full contents. You can't later fake any step of the
@@ -185,7 +188,7 @@ of history, with full contents. You can't later fake any step of the
way once you have the name of a commit.
So to introduce some real trust in the system, the only thing you need
to do is to digitally sign just _one_ special note, which includes the
to do is to digitally sign just 'one' special note, which includes the
name of a top-level commit. Your digital signature shows others
that you trust that commit, and the immutability of the history of
commits tells others that they can trust the whole history.
@ -212,8 +215,10 @@ Note that despite the tag features, "git" itself only handles content
@@ -212,8 +215,10 @@ Note that despite the tag features, "git" itself only handles content
integrity; the trust framework (and signature provision and
verification) has to come from outside.
A tag is created with link:git-mktag.html[git-mktag] and
its data can be accessed by link:git-cat-file.html[git-cat-file]
A tag is created with link:git-mktag.html[git-mktag],
its data can be accessed by link:git-cat-file.html[git-cat-file],
and the signature can be verified by
link:git-verify-tag-script.html[git-verify-tag].
The "index" aka "Current Directory Cache"
@ -228,7 +233,7 @@ meaning, and can be partially updated at any time.
@@ -228,7 +233,7 @@ meaning, and can be partially updated at any time.
In particular, the index certainly does not need to be consistent with
the current directory contents (in fact, most operations will depend on
different ways to make the index _not_ be consistent with the directory
different ways to make the index 'not' be consistent with the directory
hierarchy), but it has three very important attributes:
'(a) it can re-generate the full state it caches (not just the
@ -259,7 +264,7 @@ developed. If you blow the directory cache away entirely, you generally
@@ -259,7 +264,7 @@ developed. If you blow the directory cache away entirely, you generally
haven't lost any information as long as you have the name of the tree
that it described.
At the same time, the directory index is at the same time also the
At the same time, the index is at the same time also the
staging area for creating new trees, and creating a new tree always
involves a controlled modification of the index file. In particular,
the index file can have the representation of an intermediate tree that
@ -293,18 +298,18 @@ i.e. it will normally just update existing cache entries.
@@ -293,18 +298,18 @@ i.e. it will normally just update existing cache entries.
To tell git that yes, you really do realize that certain files no
longer exist in the archive, or that new files should be added, you
should use the "--remove" and "--add" flags respectively.
should use the `--remove` and `--add` flags respectively.
NOTE! A "--remove" flag does _not_ mean that subsequent filenames will
NOTE! A `--remove` flag does 'not' mean that subsequent filenames will
necessarily be removed: if the files still exist in your directory
structure, the index will be updated with their new status, not
removed. The only thing "--remove" means is that update-cache will be
removed. The only thing `--remove` means is that update-cache will be
considering a removed file to be a valid thing, and if the file really
does not exist any more, it will update the index accordingly.
As a special case, you can also do "git-update-cache --refresh", which
As a special case, you can also do `git-update-cache --refresh`, which
will refresh the "stat" information of each index to match the current
stat information. It will _not_ update the object status itself, and
stat information. It will 'not' update the object status itself, and
it will only update the fields that are used to quickly test whether
an object still matches its old backing store object.
@ -332,7 +337,7 @@ index. Normal operation is just
@@ -332,7 +337,7 @@ index. Normal operation is just
git-read-tree <sha1 of tree>
and your index file will now be equivalent to the tree that you saved
earlier. However, that is only your _index_ file: your working
earlier. However, that is only your 'index' file: your working
directory contents have not been modified.
4) index -> working directory
@ -342,20 +347,21 @@ You update your working directory from the index by "checking out"
@@ -342,20 +347,21 @@ You update your working directory from the index by "checking out"
files. This is not a very common operation, since normally you'd just
keep your files updated, and rather than write to your working
directory, you'd tell the index files about the changes in your
working directory (i.e. "git-update-cache").
working directory (i.e. `git-update-cache`).
However, if you decide to jump to a new version, or check out somebody
else's version, or just restore a previous tree, you'd populate your
index file with read-tree, and then you need to check out the result
with
git-checkout-cache filename
or, if you want to check out all of the index, use "-a".
or, if you want to check out all of the index, use `-a`.
NOTE! git-checkout-cache normally refuses to overwrite old files, so
if you have an old version of the tree already checked out, you will
need to use the "-f" flag (_before_ the "-a" flag or the filename) to
_force_ the checkout.
need to use the "-f" flag ('before' the "-a" flag or the filename) to
'force' the checkout.
Finally, there are a few odds and ends which are not purely moving
@ -388,9 +394,9 @@ redirection from a pipe or file, or by just typing it at the tty).
@@ -388,9 +394,9 @@ redirection from a pipe or file, or by just typing it at the tty).
git-commit-tree will return the name of the object that represents
that commit, and you should save it away for later use. Normally,
you'd commit a new "HEAD" state, and while git doesn't care where you
you'd commit a new `HEAD` state, and while git doesn't care where you
save the note about that state, in practice we tend to just write the
result to the file ".git/HEAD", so that we can always see what the
result to the file `.git/HEAD`, so that we can always see what the
Junio C Hamano
20 years ago