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[PATCH] Docs - asciidoc changes

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Whitespace and asciidoc formatting changes only in preparation for
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Signed-off-by: David Greaves <david@dgreaves.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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David Greaves 2005-05-22 18:44:16 +01:00 committed by Linus Torvalds
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@ -1,9 +1,8 @@
////////////////////////////////////////////////////////////////
GIT - the stupid content tracker GIT - the stupid content tracker
////////////////////////////////////////////////////////////////
"git" can mean anything, depending on your mood. "git" can mean anything, depending on your mood.
- random three-letter combination that is pronounceable, and not - random three-letter combination that is pronounceable, and not
@ -22,16 +21,13 @@ contents efficiently.
There are two object abstractions: the "object database", and the There are two object abstractions: the "object database", and the
"current directory cache" aka "index". "current directory cache" aka "index".
The Object Database
~~~~~~~~~~~~~~~~~~~
The Object Database (GIT_OBJECT_DIRECTORY)
The object database is literally just a content-addressable collection The object database is literally just a content-addressable collection
of objects. All objects are named by their content, which is of objects. All objects are named by their content, which is
approximated by the SHA1 hash of the object itself. Objects may refer approximated by the SHA1 hash of the object itself. Objects may refer
to other objects (by referencing their SHA1 hash), and so you can build to other objects (by referencing their SHA1 hash), and so you can
up a hierarchy of objects. build up a hierarchy of objects.
All objects have a statically determined "type" aka "tag", which is All objects have a statically determined "type" aka "tag", which is
determined at object creation time, and which identifies the format of determined at object creation time, and which identifies the format of
@ -62,12 +58,17 @@ has two or more separate roots as its ultimate parents, that's probably
just going to confuse people. So aim for the notion of "one root object just going to confuse people. So aim for the notion of "one root object
per project", even if git itself does not enforce that. per project", even if git itself does not enforce that.
A "tag" object symbolically identifies and can be used to sign other
objects. It contains the identifier and type of another object, a
symbolic name (of course!) and, optionally, a signature.
Regardless of object type, all objects are share the following Regardless of object type, all objects are share the following
characteristics: they are all in deflated with zlib, and have a header characteristics: they are all in deflated with zlib, and have a header
that not only specifies their tag, but also size information about the that not only specifies their tag, but also size information about the
data in the object. It's worth noting that the SHA1 hash that is used data in the object. It's worth noting that the SHA1 hash that is used
to name the object is always the hash of this _compressed_ object, not to name the object is the hash of the original data (historical note:
the original data. in the dawn of the age of git this was the sha1 of the _compressed_
object)
As a result, the general consistency of an object can always be tested 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 independently of the contents or the type of the object: all objects can
@ -76,157 +77,162 @@ file and (b) the object successfully inflates to a stream of bytes that
forms a sequence of <ascii tag without space> + <space> + <ascii decimal forms a sequence of <ascii tag without space> + <space> + <ascii decimal
size> + <byte\0> + <binary object data>. size> + <byte\0> + <binary object data>.
The structured objects can further have their structure and connectivity The structured objects can further have their structure and
to other objects verified. This is generally done with the "fsck-cache" connectivity to other objects verified. This is generally done with
program, which generates a full dependency graph of all objects, and the "fsck-cache" program, which generates a full dependency graph of
verifies their internal consistency (in addition to just verifying their all objects, and verifies their internal consistency (in addition to
superficial consistency through the hash). just verifying their superficial consistency through the hash).
The object types in some more detail: The object types in some more detail:
BLOB: A "blob" object is nothing but a binary blob of data, and Blob Object
doesn't refer to anything else. There is no signature or any ~~~~~~~~~~~
other verification of the data, so while the object is A "blob" object is nothing but a binary blob of data, and doesn't
consistent (it _is_ indexed by its sha1 hash, so the data itself refer to anything else. There is no signature or any other
is certainly correct), it has absolutely no other attributes. verification of the data, so while the object is consistent (it _is_
No name associations, no permissions. It is purely a blob of indexed by its sha1 hash, so the data itself is certainly correct), it
data (i.e. normally "file contents"). has absolutely no other attributes. No name associations, no
permissions. It is purely a blob of data (i.e. normally "file
contents").
In particular, since the blob is entirely defined by its data, In particular, since the blob is entirely defined by its data, if two
if two files in a directory tree (or in multiple different files in a directory tree (or in multiple different versions of the
versions of the repository) have the same contents, they will repository) have the same contents, they will share the same blob
share the same blob object. The object is totally independent object. The object is totally independent of it's location in the
of it's location in the directory tree, and renaming a file does directory tree, and renaming a file does not change the object that
not change the object that file is associated with in any way. file is associated with in any way.
TREE: The next hierarchical object type is the "tree" object. A tree Tree Object
object is a list of mode/name/blob data, sorted by name. ~~~~~~~~~~~
Alternatively, the mode data may specify a directory mode, in The next hierarchical object type is the "tree" object. A tree object
which case instead of naming a blob, that name is associated is a list of mode/name/blob data, sorted by name. Alternatively, the
with another TREE object. mode data may specify a directory mode, in which case instead of
naming a blob, that name is associated with another TREE object.
Like the "blob" object, a tree object is uniquely determined by Like the "blob" object, a tree object is uniquely determined by the
the set contents, and so two separate but identical trees will set contents, and so two separate but identical trees will always
always share the exact same object. This is true at all levels, share the exact same object. This is true at all levels, i.e. it's
i.e. it's true for a "leaf" tree (which does not refer to any true for a "leaf" tree (which does not refer to any other trees, only
other trees, only blobs) as well as for a whole subdirectory. blobs) as well as for a whole subdirectory.
For that reason a "tree" object is just a pure data abstraction: For that reason a "tree" object is just a pure data abstraction: it
it has no history, no signatures, no verification of validity, has no history, no signatures, no verification of validity, except
except that since the contents are again protected by the hash that since the contents are again protected by the hash itself, we can
itself, we can trust that the tree is immutable and its contents trust that the tree is immutable and its contents never change.
never change.
So you can trust the contents of a tree to be valid, the same So you can trust the contents of a tree to be valid, the same way you
way you can trust the contents of a blob, but you don't know can trust the contents of a blob, but you don't know where those
where those contents _came_ from. contents _came_ from.
Side note on trees: since a "tree" object is a sorted list of Side note on trees: since a "tree" object is a sorted list of
"filename+content", you can create a diff between two trees "filename+content", you can create a diff between two trees without
without actually having to unpack two trees. Just ignore all actually having to unpack two trees. Just ignore all common parts,
common parts, and your diff will look right. In other words, and your diff will look right. In other words, you can effectively
you can effectively (and efficiently) tell the difference (and efficiently) tell the difference between any two random trees by
between any two random trees by O(n) where "n" is the size of O(n) where "n" is the size of the difference, rather than the size of
the difference, rather than the size of the tree. the tree.
Side note 2 on trees: since the name of a "blob" depends Side note 2 on trees: since the name of a "blob" depends entirely and
entirely and exclusively on its contents (i.e. there are no names exclusively on its contents (i.e. there are no names or permissions
or permissions involved), you can see trivial renames or involved), you can see trivial renames or permission changes by
permission changes by noticing that the blob stayed the same. noticing that the blob stayed the same. However, renames with data
However, renames with data changes need a smarter "diff" implementation. changes need a smarter "diff" implementation.
CHANGESET: The "changeset" object is an object that introduces the
notion of history into the picture. In contrast to the other
objects, it doesn't just describe the physical state of a tree,
it describes how we got there, and why.
A "changeset" is defined by the tree-object that it results in, Changeset Object
the parent changesets (zero, one or more) that led up to that ~~~~~~~~~~~~~~~~
point, and a comment on what happened. Again, a changeset is The "changeset" object is an object that introduces the notion of
not trusted per se: the contents are well-defined and "safe" due history into the picture. In contrast to the other objects, it
to the cryptographically strong signatures at all levels, but doesn't just describe the physical state of a tree, it describes how
there is no reason to believe that the tree is "good" or that we got there, and why.
the merge information makes sense. The parents do not have to
actually have any relationship with the result, for example.
Note on changesets: unlike real SCM's, changesets do not contain A "changeset" is defined by the tree-object that it results in, the
rename information or file mode change information. All of that parent changesets (zero, one or more) that led up to that point, and a
is implicit in the trees involved (the result tree, and the comment on what happened. Again, a changeset is not trusted per se:
result trees of the parents), and describing that makes no sense the contents are well-defined and "safe" due to the cryptographically
in this idiotic file manager. strong signatures at all levels, but there is no reason to believe
that the tree is "good" or that the merge information makes sense.
The parents do not have to actually have any relationship with the
result, for example.
TRUST: The notion of "trust" is really outside the scope of "git", but Note on changesets: unlike real SCM's, changesets do not contain
it's worth noting a few things. First off, since everything is rename information or file mode change information. All of that is
hashed with SHA1, you _can_ trust that an object is intact and implicit in the trees involved (the result tree, and the result trees
has not been messed with by external sources. So the name of an of the parents), and describing that makes no sense in this idiotic
object uniquely identifies a known state - just not a state that file manager.
you may want to trust.
Furthermore, since the SHA1 signature of a changeset refers to Trust Object
the SHA1 signatures of the tree it is associated with and the ~~~~~~~~~~~~
signatures of the parent, a single named changeset specifies The notion of "trust" is really outside the scope of "git", but it's
uniquely a whole set of history, with full contents. You can't worth noting a few things. First off, since everything is hashed with
later fake any step of the way once you have the name of a SHA1, you _can_ trust that an object is intact and has not been messed
changeset. 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.
So to introduce some real trust in the system, the only thing Furthermore, since the SHA1 signature of a changeset refers to the
you need to do is to digitally sign just _one_ special note, SHA1 signatures of the tree it is associated with and the signatures
which includes the name of a top-level changeset. Your digital of the parent, a single named changeset specifies uniquely a whole set
signature shows others that you trust that changeset, and the of history, with full contents. You can't later fake any step of the
immutability of the history of changesets tells others that they way once you have the name of a changeset.
can trust the whole history.
In other words, you can easily validate a whole archive by just So to introduce some real trust in the system, the only thing you need
sending out a single email that tells the people the name (SHA1 to do is to digitally sign just _one_ special note, which includes the
hash) of the top changeset, and digitally sign that email using name of a top-level changeset. Your digital signature shows others
something like GPG/PGP. that you trust that changeset, and the immutability of the history of
changesets tells others that they can trust the whole history.
In particular, you can also have a separate archive of "trust In other words, you can easily validate a whole archive by just
points" or tags, which document your (and other peoples) trust. sending out a single email that tells the people the name (SHA1 hash)
You may, of course, archive these "certificates of trust" using of the top changeset, and digitally sign that email using something
"git" itself, but it's not something "git" does for you. like GPG/PGP.
Another way of saying the last point: "git" itself only handles content In particular, you can also have a separate archive of "trust points"
integrity, the trust has to come from outside. or tags, which document your (and other peoples) trust. You may, of
course, archive these "certificates of trust" using "git" itself, but
it's not something "git" does for you.
Another way of saying the last point: "git" itself only handles
content integrity, the trust has to come from outside.
The "index" aka "Current Directory Cache" (".git/index")
The "index" aka "Current Directory Cache"
-----------------------------------------
The index is a simple binary file, which contains an efficient The index is a simple binary file, which contains an efficient
representation of a virtual directory content at some random time. It representation of a virtual directory content at some random time. It
does so by a simple array that associates a set of names, dates, does so by a simple array that associates a set of names, dates,
permissions and content (aka "blob") objects together. The cache is permissions and content (aka "blob") objects together. The cache is
always kept ordered by name, and names are unique (with a few very always kept ordered by name, and names are unique (with a few very
specific rules) at any point in time, but the cache has no long-term specific rules) at any point in time, but the cache has no long-term
meaning, and can be partially updated at any time. meaning, and can be partially updated at any time.
In particular, the index certainly does not need to be consistent with In particular, the index certainly does not need to be consistent with
the current directory contents (in fact, most operations will depend on 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: hierarchy), but it has three very important attributes:
(a) it can re-generate the full state it caches (not just the directory '(a) it can re-generate the full state it caches (not just the
structure: it contains pointers to the "blob" objects so that it directory structure: it contains pointers to the "blob" objects so
can regenerate the data too) that it can regenerate the data too)'
As a special case, there is a clear and unambiguous one-way mapping As a special case, there is a clear and unambiguous one-way mapping
from a current directory cache to a "tree object", which can be from a current directory cache to a "tree object", which can be
efficiently created from just the current directory cache without efficiently created from just the current directory cache without
actually looking at any other data. So a directory cache at any actually looking at any other data. So a directory cache at any one
one time uniquely specifies one and only one "tree" object (but time uniquely specifies one and only one "tree" object (but has
has additional data to make it easy to match up that tree object additional data to make it easy to match up that tree object with what
with what has happened in the directory) has happened in the directory)
(b) it has efficient methods for finding inconsistencies between that '(b) it has efficient methods for finding inconsistencies between that
cached state ("tree object waiting to be instantiated") and the cached state ("tree object waiting to be instantiated") and the
current state. current state.'
(c) it can additionally efficiently represent information about merge '(c) it can additionally efficiently represent information about merge
conflicts between different tree objects, allowing each pathname to conflicts between different tree objects, allowing each pathname to be
be associated with sufficient information about the trees involved associated with sufficient information about the trees involved that
that you can create a three-way merge between them. you can create a three-way merge between them.'
Those are the three ONLY things that the directory cache does. It's a Those are the three ONLY things that the directory cache does. It's a
cache, and the normal operation is to re-generate it completely from a cache, and the normal operation is to re-generate it completely from a
@ -241,220 +247,216 @@ involves a controlled modification of the index file. In particular,
the index file can have the representation of an intermediate tree that the index file can have the representation of an intermediate tree that
has not yet been instantiated. So the index can be thought of as a has not yet been instantiated. So the index can be thought of as a
write-back cache, which can contain dirty information that has not yet write-back cache, which can contain dirty information that has not yet
been written back to the backing store. been written back to the backing store.
The Workflow The Workflow
------------
Generally, all "git" operations work on the index file. Some operations Generally, all "git" operations work on the index file. Some operations
work _purely_ on the index file (showing the current state of the work *purely* on the index file (showing the current state of the
index), but most operations move data to and from the index file. Either index), but most operations move data to and from the index file. Either
from the database or from the working directory. Thus there are four from the database or from the working directory. Thus there are four
main combinations: main combinations:
1) working directory -> index 1) working directory -> index
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
You update the index with information from the working directory You update the index with information from the working directory with
with the "update-cache" command. You generally update the index the "update-cache" command. You generally update the index
information by just specifying the filename you want to update, information by just specifying the filename you want to update, like
like so: so:
update-cache filename update-cache filename
but to avoid common mistakes with filename globbing etc, the but to avoid common mistakes with filename globbing etc, the command
command will not normally add totally new entries or remove old will not normally add totally new entries or remove old entries,
entries, i.e. it will normally just update existing cache entries. i.e. it will normally just update existing cache entries.
To tell git that yes, you really do realize that certain files To tell git that yes, you really do realize that certain files no
no longer exist in the archive, or that new files should be longer exist in the archive, or that new files should be added, you
added, you should use the "--remove" and "--add" flags should use the "--remove" and "--add" flags respectively.
respectively.
NOTE! A "--remove" flag does _not_ mean that subsequent NOTE! A "--remove" flag does _not_ mean that subsequent filenames will
filenames will necessarily be removed: if the files still exist necessarily be removed: if the files still exist in your directory
in your directory structure, the index will be updated with structure, the index will be updated with their new status, not
their new status, not removed. The only thing "--remove" means removed. The only thing "--remove" means is that update-cache will be
is that update-cache will be considering a removed file to be a considering a removed file to be a valid thing, and if the file really
valid thing, and if the file really does not exist any more, it does not exist any more, it will update the index accordingly.
will update the index accordingly.
As a special case, you can also do "update-cache --refresh", As a special case, you can also do "update-cache --refresh", which
which will refresh the "stat" information of each index to match will refresh the "stat" information of each index to match the current
the current stat information. It will _not_ update the object stat information. It will _not_ update the object status itself, and
status itself, and it will only update the fields that are used it will only update the fields that are used to quickly test whether
to quickly test whether an object still matches its old backing an object still matches its old backing store object.
store object.
2) index -> object database 2) index -> object database
~~~~~~~~~~~~~~~~~~~~~~~~~~~
You write your current index file to a "tree" object with the You write your current index file to a "tree" object with the program
program
write-tree write-tree
that doesn't come with any options - it will just write out the that doesn't come with any options - it will just write out the
current index into the set of tree objects that describe that current index into the set of tree objects that describe that state,
state, and it will return the name of the resulting top-level and it will return the name of the resulting top-level tree. You can
tree. You can use that tree to re-generate the index at any time use that tree to re-generate the index at any time by going in the
by going in the other direction: other direction:
3) object database -> index 3) object database -> index
~~~~~~~~~~~~~~~~~~~~~~~~~~~
You read a "tree" file from the object database, and use that to You read a "tree" file from the object database, and use that to
populate (and overwrite - don't do this if your index contains populate (and overwrite - don't do this if your index contains any
any unsaved state that you might want to restore later!) your unsaved state that you might want to restore later!) your current
current index. Normal operation is just index. Normal operation is just
read-tree <sha1 of tree> read-tree <sha1 of tree>
and your index file will now be equivalent to the tree that you and your index file will now be equivalent to the tree that you saved
saved earlier. However, that is only your _index_ file: your earlier. However, that is only your _index_ file: your working
working directory contents have not been modified. directory contents have not been modified.
4) index -> working directory 4) index -> working directory
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
You update your working directory from the index by "checking You update your working directory from the index by "checking out"
out" files. This is not a very common operation, since normally files. This is not a very common operation, since normally you'd just
you'd just keep your files updated, and rather than write to keep your files updated, and rather than write to your working
your working directory, you'd tell the index files about the directory, you'd tell the index files about the changes in your
changes in your working directory (i.e. "update-cache"). working directory (i.e. "update-cache").
However, if you decide to jump to a new version, or check out However, if you decide to jump to a new version, or check out somebody
somebody else's version, or just restore a previous tree, you'd else's version, or just restore a previous tree, you'd populate your
populate your index file with read-tree, and then you need to index file with read-tree, and then you need to check out the result
check out the result with with
checkout-cache filename 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! checkout-cache normally refuses to overwrite old files, so NOTE! checkout-cache normally refuses to overwrite old files, so if
if you have an old version of the tree already checked out, you you have an old version of the tree already checked out, you will need
will need to use the "-f" flag (_before_ the "-a" flag or the to use the "-f" flag (_before_ the "-a" flag or the filename) to
filename) to _force_ the checkout. _force_ the checkout.
Finally, there are a few odds and ends which are not purely moving from Finally, there are a few odds and ends which are not purely moving
one representation to the other: from one representation to the other:
5) Tying it all together 5) Tying it all together
~~~~~~~~~~~~~~~~~~~~~~~~
To commit a tree you have instantiated with "write-tree", you'd To commit a tree you have instantiated with "write-tree", you'd create
create a "commit" object that refers to that tree and the a "commit" object that refers to that tree and the history behind it -
history behind it - most notably the "parent" commits that most notably the "parent" commits that preceded it in history.
preceded it in history.
Normally a "commit" has one parent: the previous state of the Normally a "commit" has one parent: the previous state of the tree
tree before a certain change was made. However, sometimes it can before a certain change was made. However, sometimes it can have two
have two or more parent commits, in which case we call it a or more parent commits, in which case we call it a "merge", due to the
"merge", due to the fact that such a commit brings together fact that such a commit brings together ("merges") two or more
("merges") two or more previous states represented by other previous states represented by other commits.
commits.
In other words, while a "tree" represents a particular directory In other words, while a "tree" represents a particular directory state
state of a working directory, a "commit" represents that state of a working directory, a "commit" represents that state in "time",
in "time", and explains how we got there. and explains how we got there.
You create a commit object by giving it the tree that describes You create a commit object by giving it the tree that describes the
the state at the time of the commit, and a list of parents: state at the time of the commit, and a list of parents:
commit-tree <tree> -p <parent> [-p <parent2> ..] commit-tree <tree> -p <parent> [-p <parent2> ..]
and then giving the reason for the commit on stdin (either and then giving the reason for the commit on stdin (either through
through redirection from a pipe or file, or by just typing it at redirection from a pipe or file, or by just typing it at the tty).
the tty).
commit-tree will return the name of the object that represents commit-tree will return the name of the object that represents that
that commit, and you should save it away for later use. commit, and you should save it away for later use. Normally, you'd
Normally, you'd commit a new "HEAD" state, and while git doesn't commit a new "HEAD" state, and while git doesn't care where you save
care where you save the note about that state, in practice we the note about that state, in practice we tend to just write the
tend to just write the result to the file ".git/HEAD", so that result to the file ".git/HEAD", so that we can always see what the
we can always see what the last committed state was. last committed state was.
6) Examining the data 6) Examining the data
~~~~~~~~~~~~~~~~~~~~~
You can examine the data represented in the object database and You can examine the data represented in the object database and the
the index with various helper tools. For every object, you can index with various helper tools. For every object, you can use
use "cat-file" to examine details about the object: "cat-file" to examine details about the object:
cat-file -t <objectname> cat-file -t <objectname>
shows the type of the object, and once you have the type (which shows the type of the object, and once you have the type (which is
is usually implicit in where you find the object), you can use usually implicit in where you find the object), you can use
cat-file blob|tree|commit <objectname> cat-file blob|tree|commit <objectname>
to show its contents. NOTE! Trees have binary content, and as a to show its contents. NOTE! Trees have binary content, and as a result
result there is a special helper for showing that content, there is a special helper for showing that content, called "ls-tree",
called "ls-tree", which turns the binary content into a more which turns the binary content into a more easily readable form.
easily readable form.
It's especially instructive to look at "commit" objects, since It's especially instructive to look at "commit" objects, since those
those tend to be small and fairly self-explanatory. In tend to be small and fairly self-explanatory. In particular, if you
particular, if you follow the convention of having the top follow the convention of having the top commit name in ".git/HEAD",
commit name in ".git/HEAD", you can do you can do
cat-file commit $(cat .git/HEAD) cat-file commit $(cat .git/HEAD)
to see what the top commit was. to see what the top commit was.
7) Merging multiple trees 7) Merging multiple trees
~~~~~~~~~~~~~~~~~~~~~~~~~
Git helps you do a three-way merge, which you can expand to Git helps you do a three-way merge, which you can expand to n-way by
n-way by repeating the merge procedure arbitrary times until you repeating the merge procedure arbitrary times until you finally
finally "commit" the state. The normal situation is that you'd "commit" the state. The normal situation is that you'd only do one
only do one three-way merge (two parents), and commit it, but if three-way merge (two parents), and commit it, but if you like to, you
you like to, you can do multiple parents in one go. can do multiple parents in one go.
To do a three-way merge, you need the two sets of "commit" To do a three-way merge, you need the two sets of "commit" objects
objects that you want to merge, use those to find the closest that you want to merge, use those to find the closest common parent (a
common parent (a third "commit" object), and then use those third "commit" object), and then use those commit objects to find the
commit objects to find the state of the directory ("tree" state of the directory ("tree" object) at these points.
object) at these points.
To get the "base" for the merge, you first look up the common To get the "base" for the merge, you first look up the common parent
parent of two commits with of two commits with
merge-base <commit1> <commit2> merge-base <commit1> <commit2>
which will return you the commit they are both based on. You which will return you the commit they are both based on. You should
should now look up the "tree" objects of those commits, which now look up the "tree" objects of those commits, which you can easily
you can easily do with (for example) do with (for example)
cat-file commit <commitname> | head -1 cat-file commit <commitname> | head -1
since the tree object information is always the first line in a since the tree object information is always the first line in a commit
commit object. object.
Once you know the three trees you are going to merge (the one Once you know the three trees you are going to merge (the one
"original" tree, aka the common case, and the two "result" trees, "original" tree, aka the common case, and the two "result" trees, aka
aka the branches you want to merge), you do a "merge" read into the branches you want to merge), you do a "merge" read into the
the index. This will throw away your old index contents, so you index. This will throw away your old index contents, so you should
should make sure that you've committed those - in fact you would make sure that you've committed those - in fact you would normally
normally always do a merge against your last commit (which always do a merge against your last commit (which should thus match
should thus match what you have in your current index anyway). what you have in your current index anyway).
To do the merge, do
To do the merge, do
read-tree -m <origtree> <target1tree> <target2tree> read-tree -m <origtree> <target1tree> <target2tree>
which will do all trivial merge operations for you directly in which will do all trivial merge operations for you directly in the
the index file, and you can just write the result out with index file, and you can just write the result out with "write-tree".
"write-tree".
NOTE! Because the merge is done in the index file, and not in NOTE! Because the merge is done in the index file, and not in your
your working directory, your working directory will no longer working directory, your working directory will no longer match your
match your index. You can use "checkout-cache -f -a" to make the index. You can use "checkout-cache -f -a" to make the effect of the
effect of the merge be seen in your working directory. merge be seen in your working directory.
NOTE2! Sadly, many merges aren't trivial. If there are files NOTE2! Sadly, many merges aren't trivial. If there are files that have
that have been added.moved or removed, or if both branches have been added.moved or removed, or if both branches have modified the
modified the same file, you will be left with an index tree that same file, you will be left with an index tree that contains "merge
contains "merge entries" in it. Such an index tree can _NOT_ be entries" in it. Such an index tree can _NOT_ be written out to a tree
written out to a tree object, and you will have to resolve any object, and you will have to resolve any such merge clashes using
such merge clashes using other tools before you can write out other tools before you can write out the result.
the result.
[ fixme: talk about resolving merges here ]
[ fixme: talk about resolving merges here ]