git-commit-vandalism/Documentation/git-bundle.txt
brian m. carlson c5aecfc866 bundle: add new version for use with SHA-256
Currently we detect the hash algorithm in use by the length of the
object ID.  This is inelegant and prevents us from using a different
hash algorithm that is also 256 bits in length.

Since we cannot extend the v2 format in a backward-compatible way, let's
add a v3 format, which is identical, except for the addition of
capabilities, which are prefixed by an at sign.  We add "object-format"
as the only capability and reject unknown capabilities, since we do not
have a network connection and therefore cannot negotiate with the other
side.

For compatibility, default to the v2 format for SHA-1 and require v3
for SHA-256.

In t5510, always use format v3 so we can be sure we produce consistent
results across hash algorithms.  Since head -n N lists the top N lines
instead of the Nth line, let's run our output through sed to normalize
it and compare it against a fixed value, which will make sure we get
exactly what we're expecting.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-07-30 09:16:48 -07:00

253 lines
8.7 KiB
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git-bundle(1)
=============
NAME
----
git-bundle - Move objects and refs by archive
SYNOPSIS
--------
[verse]
'git bundle' create [-q | --quiet | --progress | --all-progress] [--all-progress-implied]
[--version=<version>] <file> <git-rev-list-args>
'git bundle' verify [-q | --quiet] <file>
'git bundle' list-heads <file> [<refname>...]
'git bundle' unbundle <file> [<refname>...]
DESCRIPTION
-----------
Some workflows require that one or more branches of development on one
machine be replicated on another machine, but the two machines cannot
be directly connected, and therefore the interactive Git protocols (git,
ssh, http) cannot be used.
The 'git bundle' command packages objects and references in an archive
at the originating machine, which can then be imported into another
repository using 'git fetch', 'git pull', or 'git clone',
after moving the archive by some means (e.g., by sneakernet).
As no
direct connection between the repositories exists, the user must specify a
basis for the bundle that is held by the destination repository: the
bundle assumes that all objects in the basis are already in the
destination repository.
OPTIONS
-------
create [options] <file> <git-rev-list-args>::
Used to create a bundle named 'file'. This requires the
'<git-rev-list-args>' arguments to define the bundle contents.
'options' contains the options specific to the 'git bundle create'
subcommand.
verify <file>::
Used to check that a bundle file is valid and will apply
cleanly to the current repository. This includes checks on the
bundle format itself as well as checking that the prerequisite
commits exist and are fully linked in the current repository.
'git bundle' prints a list of missing commits, if any, and exits
with a non-zero status.
list-heads <file>::
Lists the references defined in the bundle. If followed by a
list of references, only references matching those given are
printed out.
unbundle <file>::
Passes the objects in the bundle to 'git index-pack'
for storage in the repository, then prints the names of all
defined references. If a list of references is given, only
references matching those in the list are printed. This command is
really plumbing, intended to be called only by 'git fetch'.
<git-rev-list-args>::
A list of arguments, acceptable to 'git rev-parse' and
'git rev-list' (and containing a named ref, see SPECIFYING REFERENCES
below), that specifies the specific objects and references
to transport. For example, `master~10..master` causes the
current master reference to be packaged along with all objects
added since its 10th ancestor commit. There is no explicit
limit to the number of references and objects that may be
packaged.
[<refname>...]::
A list of references used to limit the references reported as
available. This is principally of use to 'git fetch', which
expects to receive only those references asked for and not
necessarily everything in the pack (in this case, 'git bundle' acts
like 'git fetch-pack').
--progress::
Progress status is reported on the standard error stream
by default when it is attached to a terminal, unless -q
is specified. This flag forces progress status even if
the standard error stream is not directed to a terminal.
--all-progress::
When --stdout is specified then progress report is
displayed during the object count and compression phases
but inhibited during the write-out phase. The reason is
that in some cases the output stream is directly linked
to another command which may wish to display progress
status of its own as it processes incoming pack data.
This flag is like --progress except that it forces progress
report for the write-out phase as well even if --stdout is
used.
--all-progress-implied::
This is used to imply --all-progress whenever progress display
is activated. Unlike --all-progress this flag doesn't actually
force any progress display by itself.
--version=<version>::
Specify the bundle version. Version 2 is the older format and can only be
used with SHA-1 repositories; the newer version 3 contains capabilities that
permit extensions. The default is the oldest supported format, based on the
hash algorithm in use.
-q::
--quiet::
This flag makes the command not to report its progress
on the standard error stream.
SPECIFYING REFERENCES
---------------------
'git bundle' will only package references that are shown by
'git show-ref': this includes heads, tags, and remote heads. References
such as `master~1` cannot be packaged, but are perfectly suitable for
defining the basis. More than one reference may be packaged, and more
than one basis can be specified. The objects packaged are those not
contained in the union of the given bases. Each basis can be
specified explicitly (e.g. `^master~10`), or implicitly (e.g.
`master~10..master`, `--since=10.days.ago master`).
It is very important that the basis used be held by the destination.
It is okay to err on the side of caution, causing the bundle file
to contain objects already in the destination, as these are ignored
when unpacking at the destination.
`git clone` can use any bundle created without negative refspecs
(e.g., `new`, but not `old..new`).
If you want to match `git clone --mirror`, which would include your
refs such as `refs/remotes/*`, use `--all`.
If you want to provide the same set of refs that a clone directly
from the source repository would get, use `--branches --tags` for
the `<git-rev-list-args>`.
EXAMPLES
--------
Assume you want to transfer the history from a repository R1 on machine A
to another repository R2 on machine B.
For whatever reason, direct connection between A and B is not allowed,
but we can move data from A to B via some mechanism (CD, email, etc.).
We want to update R2 with development made on the branch master in R1.
To bootstrap the process, you can first create a bundle that does not have
any basis. You can use a tag to remember up to what commit you last
processed, in order to make it easy to later update the other repository
with an incremental bundle:
----------------
machineA$ cd R1
machineA$ git bundle create file.bundle master
machineA$ git tag -f lastR2bundle master
----------------
Then you transfer file.bundle to the target machine B. Because this
bundle does not require any existing object to be extracted, you can
create a new repository on machine B by cloning from it:
----------------
machineB$ git clone -b master /home/me/tmp/file.bundle R2
----------------
This will define a remote called "origin" in the resulting repository that
lets you fetch and pull from the bundle. The $GIT_DIR/config file in R2 will
have an entry like this:
------------------------
[remote "origin"]
url = /home/me/tmp/file.bundle
fetch = refs/heads/*:refs/remotes/origin/*
------------------------
To update the resulting mine.git repository, you can fetch or pull after
replacing the bundle stored at /home/me/tmp/file.bundle with incremental
updates.
After working some more in the original repository, you can create an
incremental bundle to update the other repository:
----------------
machineA$ cd R1
machineA$ git bundle create file.bundle lastR2bundle..master
machineA$ git tag -f lastR2bundle master
----------------
You then transfer the bundle to the other machine to replace
/home/me/tmp/file.bundle, and pull from it.
----------------
machineB$ cd R2
machineB$ git pull
----------------
If you know up to what commit the intended recipient repository should
have the necessary objects, you can use that knowledge to specify the
basis, giving a cut-off point to limit the revisions and objects that go
in the resulting bundle. The previous example used the lastR2bundle tag
for this purpose, but you can use any other options that you would give to
the linkgit:git-log[1] command. Here are more examples:
You can use a tag that is present in both:
----------------
$ git bundle create mybundle v1.0.0..master
----------------
You can use a basis based on time:
----------------
$ git bundle create mybundle --since=10.days master
----------------
You can use the number of commits:
----------------
$ git bundle create mybundle -10 master
----------------
You can run `git-bundle verify` to see if you can extract from a bundle
that was created with a basis:
----------------
$ git bundle verify mybundle
----------------
This will list what commits you must have in order to extract from the
bundle and will error out if you do not have them.
A bundle from a recipient repository's point of view is just like a
regular repository which it fetches or pulls from. You can, for example, map
references when fetching:
----------------
$ git fetch mybundle master:localRef
----------------
You can also see what references it offers:
----------------
$ git ls-remote mybundle
----------------
GIT
---
Part of the linkgit:git[1] suite