GIT v1.5.0 Release Notes
========================
Old news
--------
This section is for people who are upgrading from ancient
versions of git. Although all of the changes in this section
happened before the current v1.4.4 release, they are summarized
here in the v1.5.0 release notes for people who skipped earlier
versions.
As of git v1.5.0 there are some optional features that changes
the repository to allow data to be stored and transferred more
efficiently. These features are not enabled by default, as they
will make the repository unusable with older versions of git.
Specifically, the available options are:
- There is a configuration variable core.legacyheaders that
changes the format of loose objects so that they are more
efficient to pack and to send out of the repository over git
native protocol, since v1.4.2. However, loose objects
written in the new format cannot be read by git older than
that version; people fetching from your repository using
older clients over dumb transports (e.g. http) using older
versions of git will also be affected.
To let git use the new loose object format, you have to
set core.legacyheaders to false.
- Since v1.4.3, configuration repack.usedeltabaseoffset allows
packfile to be created in more space efficient format, which
cannot be read by git older than that version.
To let git use the new format for packfiles, you have to
set repack.usedeltabaseoffset to true.
The above two new features are not enabled by default and you
have to explicitly ask for them, because they make repositories
unreadable by older versions of git, and in v1.5.0 we still do
not enable them by default for the same reason. We will change
this default probably 1 year after 1.4.2's release, when it is
reasonable to expect everybody to have new enough version of
git.
- 'git pack-refs' appeared in v1.4.4; this command allows tags
to be accessed much more efficiently than the traditional
'one-file-per-tag' format. Older git-native clients can
still fetch from a repository that packed and pruned refs
(the server side needs to run the up-to-date version of git),
but older dumb transports cannot. Packing of refs is done by
an explicit user action, either by use of "git pack-refs
--prune" command or by use of "git gc" command.
- 'git -p' to paginate anything -- many commands do pagination
by default on a tty. Introduced between v1.4.1 and v1.4.2;
this may surprise old timers.
- 'git archive' superseded 'git tar-tree' in v1.4.3;
- 'git cvsserver' was new invention in v1.3.0;
- 'git repo-config', 'git grep', 'git rebase' and 'gitk' were
seriously enhanced during v1.4.0 timeperiod.
- 'gitweb' became part of git.git during v1.4.0 timeperiod and
seriously modified since then.
- reflog is an v1.4.0 invention. This allows you to name a
revision that a branch used to be at (e.g. "git diff
master@{yesterday} master" allows you to see changes since
yesterday's tip of the branch).
Updates in v1.5.0 since v1.4.4 series
-------------------------------------
* Index manipulation
- git-add is to add contents to the index (aka "staging area"
for the next commit), whether the file the contents happen to
be is an existing one or a newly created one.
- git-add without any argument does not add everything
anymore. Use 'git-add .' instead. Also you can add
otherwise ignored files with an -f option.
- git-add tries to be more friendly to users by offering an
interactive mode ("git-add -i").
- git-commit <path> used to refuse to commit if <path> was
different between HEAD and the index (i.e. update-index was
used on it earlier). This check was removed.
- git-rm is much saner and safer. It is used to remove paths
from both the index file and the working tree, and makes sure
you are not losing any local modification before doing so.
- git-reset <tree> <paths>... can be used to revert index
entries for selected paths.
- git-update-index is much less visible. Many suggestions to
use the command in git output and documentation have now been
replaced by simpler commands such as "git add" or "git rm".
* Repository layout and objects transfer
- The data for origin repository is stored in the configuration
file $GIT_DIR/config, not in $GIT_DIR/remotes/, for newly
created clones. The latter is still supported and there is
no need to convert your existing repository if you are
already comfortable with your workflow with the layout.
- git-clone always uses what is known as "separate remote"
layout for a newly created repository with a working tree.
A repository with the separate remote layout starts with only
one default branch, 'master', to be used for your own
development. Unlike the traditional layout that copied all
the upstream branches into your branch namespace (while
renaming their 'master' to your 'origin'), the new layout
puts upstream branches into local "remote-tracking branches"
with their own namespace. These can be referenced with names
such as "origin/$upstream_branch_name" and are stored in
.git/refs/remotes rather than .git/refs/heads where normal
branches are stored.
This layout keeps your own branch namespace less cluttered,
avoids name collision with your upstream, makes it possible
to automatically track new branches created at the remote
after you clone from it, and makes it easier to interact with
more than one remote repository (you can use "git remote" to
add other repositories to track). There might be some
surprises:
* 'git branch' does not show the remote tracking branches.
It only lists your own branches. Use '-r' option to view
the tracking branches.
* If you are forking off of a branch obtained from the
upstream, you would have done something like 'git branch
my-next next', because traditional layout dropped the
tracking branch 'next' into your own branch namespace.
With the separate remote layout, you say 'git branch next
origin/next', which allows you to use the matching name
'next' for your own branch. It also allows you to track a
remote other than 'origin' (i.e. where you initially cloned
from) and fork off of a branch from there the same way
(e.g. "git branch mingw j6t/master").
Repositories initialized with the traditional layout continue
to work.
- New branches that appear on the origin side after a clone is
made are also tracked automatically. This is done with an
wildcard refspec "refs/heads/*:refs/remotes/origin/*", which
older git does not understand, so if you clone with 1.5.0,
you would need to downgrade remote.*.fetch in the
configuration file to specify each branch you are interested
in individually if you plan to fetch into the repository with
older versions of git (but why would you?).
- Similarly, wildcard refspec "refs/heads/*:refs/remotes/me/*"
can be given to "git-push" command to update the tracking
branches that is used to track the repository you are pushing
from on the remote side.
- git-branch and git-show-branch know remote tracking branches
(use the command line switch "-r" to list only tracked branches).
- git-push can now be used to delete a remote branch or a tag.
This requires the updated git on the remote side (use "git
push <remote> :refs/heads/<branch>" to delete "branch").
- git-push more aggressively keeps the transferred objects
packed. Earlier we recommended to monitor amount of loose
objects and repack regularly, but you should repack when you
accumulated too many small packs this way as well. Updated
git-count-objects helps you with this.
- git-fetch also more aggressively keeps the transferred objects
packed. This behavior of git-push and git-fetch can be
tweaked with a single configuration transfer.unpacklimit (but
usually there should not be any need for a user to tweak it).
- A new command, git-remote, can help you manage your remote
tracking branch definitions.
- You may need to specify explicit paths for upload-pack and/or
receive-pack due to your ssh daemon configuration on the
other end. This can now be done via remote.*.uploadpack and
remote.*.receivepack configuration.
* Bare repositories
- Certain commands change their behavior in a bare repository
(i.e. a repository without associated working tree). We use
a fairly conservative heuristic (if $GIT_DIR is ".git", or
ends with "/.git", the repository is not bare) to decide if a
repository is bare, but "core.bare" configuration variable
can be used to override the heuristic when it misidentifies
your repository.
- git-fetch used to complain updating the current branch but
this is now allowed for a bare repository. So is the use of
'git-branch -f' to update the current branch.
- Porcelain-ish commands that require a working tree refuses to
work in a bare repository.
* Reflog
- Reflog records the history from the view point of the local
repository. In other words, regardless of the real history,
the reflog shows the history as seen by one particular
repository (this enables you to ask "what was the current
revision in _this_ repository, yesterday at 1pm?"). This
facility is enabled by default for repositories with working
trees, and can be accessed with the "branch@{time}" and
"branch@{Nth}" notation.
- "git show-branch" learned showing the reflog data with the
new -g option. "git log" has -g option to view reflog
entries in a more verbose manner.
- git-branch knows how to rename branches and moves existing
reflog data from the old branch to the new one.
- In addition to the reflog support in v1.4.4 series, HEAD
reference maintains its own log. "HEAD@{5.minutes.ago}"
means the commit you were at 5 minutes ago, which takes
branch switching into account. If you want to know where the
tip of your current branch was at 5 minutes ago, you need to
explicitly say its name (e.g. "master@{5.minutes.ago}") or
omit the refname altogether i.e. "@{5.minutes.ago}".
- The commits referred to by reflog entries are now protected
against pruning. The new command "git reflog expire" can be
used to truncate older reflog entries and entries that refer
to commits that have been pruned away previously with older
versions of git.
Existing repositories that have been using reflog may get
complaints from fsck-objects and may not be able to run
git-repack, if you had run git-prune from older git; please
run "git reflog expire --stale-fix --all" first to remove
reflog entries that refer to commits that are no longer in
the repository when that happens.
* Cruft removal
- We used to say "old commits are retrievable using reflog and
'master@{yesterday}' syntax as long as you haven't run
git-prune". We no longer have to say the latter half of the
above sentence, as git-prune does not remove things reachable
from reflog entries.
- There is a toplevel garbage collector script, 'git-gc', that
runs periodic cleanup functions, including 'git-repack -a -d',
'git-reflog expire', 'git-pack-refs --prune', and 'git-rerere
gc'.
- The output from fsck ("fsck-objects" is called just "fsck"
now, but the old name continues to work) was needlessly
alarming in that it warned missing objects that are reachable
only from dangling objects. This has been corrected and the
output is much more useful.
* Detached HEAD
- You can use 'git-checkout' to check out an arbitrary revision
or a tag as well, instead of named branches. This will
dissociate your HEAD from the branch you are currently on.
A typical use of this feature is to "look around". E.g.
$ git checkout v2.6.16
... compile, test, etc.
$ git checkout v2.6.17
... compile, test, etc.
- After detaching your HEAD, you can go back to an existing
branch with usual "git checkout $branch". Also you can
start a new branch using "git checkout -b $newbranch" to
start a new branch at that commit.
- You can even pull from other repositories, make merges and
commits while your HEAD is detached. Also you can use "git
reset" to jump to arbitrary commit, while still keeping your
HEAD detached.
Remember that a detached state is volatile, i.e. it will be forgotten
as soon as you move away from it with the checkout or reset command,
unless a branch is created from it as mentioned above. It is also
possible to rescue a lost detached state from the HEAD reflog.
* Packed refs
- Repositories with hundreds of tags have been paying large
overhead, both in storage and in runtime, due to the
traditional one-ref-per-file format. A new command,
git-pack-refs, can be used to "pack" them in more efficient
representation (you can let git-gc do this for you).
- Clones and fetches over dumb transports are now aware of
packed refs and can download from repositories that use
them.
* Configuration
- configuration related to color setting are consolidated under
color.* namespace (older diff.color.*, status.color.* are
still supported).
- 'git-repo-config' command is accessible as 'git-config' now.
* Updated features
- git-describe uses better criteria to pick a base ref. It
used to pick the one with the newest timestamp, but now it
picks the one that is topologically the closest (that is,
among ancestors of commit C, the ref T that has the shortest
output from "git-rev-list T..C" is chosen).
- git-describe gives the number of commits since the base ref
between the refname and the hash suffix. E.g. the commit one
before v2.6.20-rc6 in the kernel repository is:
v2.6.20-rc5-306-ga21b069
which tells you that its object name begins with a21b069,
v2.6.20-rc5 is an ancestor of it (meaning, the commit
contains everything -rc5 has), and there are 306 commits
since v2.6.20-rc5.
- git-describe with --abbrev=0 can be used to show only the
name of the base ref.
- git-blame learned a new option, --incremental, that tells it
to output the blames as they are assigned. A sample script
to use it is also included as contrib/blameview.
- git-blame starts annotating from the working tree by default.
* Less external dependency
- We no longer require the "merge" program from the RCS suite.
All 3-way file-level merges are now done internally.
- The original implementation of git-merge-recursive which was
in Python has been removed; we have a C implementation of it
now.
- git-shortlog is no longer a Perl script. It no longer
requires output piped from git-log; it can accept revision
parameters directly on the command line.
* I18n
- We have always encouraged the commit message to be encoded in
UTF-8, but the users are allowed to use legacy encoding as
appropriate for their projects. This will continue to be the
case. However, a non UTF-8 commit encoding _must_ be
explicitly set with i18n.commitencoding in the repository
where a commit is made; otherwise git-commit-tree will
complain if the log message does not look like a valid UTF-8
string.
- The value of i18n.commitencoding in the originating
repository is recorded in the commit object on the "encoding"
header, if it is not UTF-8. git-log and friends notice this,
and re-encodes the message to the log output encoding when
displaying, if they are different. The log output encoding
is determined by "git log --encoding=<encoding>",
i18n.logoutputencoding configuration, or i18n.commitencoding
configuration, in the decreasing order of preference, and
defaults to UTF-8.
- Tools for e-mailed patch application now default to -u
behavior; i.e. it always re-codes from the e-mailed encoding
to the encoding specified with i18n.commitencoding. This
unfortunately forces projects that have happily been using a
legacy encoding without setting i18n.commitencoding to set
the configuration, but taken with other improvement, please
excuse us for this very minor one-time inconvenience.
* e-mailed patches
- See the above I18n section.
- git-format-patch now enables --binary without being asked.
git-am does _not_ default to it, as sending binary patch via
e-mail is unusual and is harder to review than textual
patches and it is prudent to require the person who is
applying the patch to explicitly ask for it.
- The default suffix for git-format-patch output is now ".patch",
not ".txt". This can be changed with --suffix=.txt option,
or setting the config variable "format.suffix" to ".txt".
* Foreign SCM interfaces
- git-svn now requires the Perl SVN:: libraries, the
command-line backend was too slow and limited.
- the 'commit' subcommand of git-svn has been renamed to
'set-tree', and 'dcommit' is the recommended replacement for
day-to-day work.
- git fast-import backend.
* User support
- Quite a lot of documentation updates.
- Bash completion scripts have been updated heavily.
- Better error messages for often used Porcelainish commands.
- Git GUI. This is a simple Tk based graphical interface for
common Git operations.
* Sliding mmap
- We used to assume that we can mmap the whole packfile while
in use, but with a large project this consumes huge virtual
memory space and truly huge ones would not fit in the
userland address space on 32-bit platforms. We now mmap huge
packfile in pieces to avoid this problem.
* Shallow clones
- There is a partial support for 'shallow' repositories that
keeps only recent history. A 'shallow clone' is created by
specifying how deep that truncated history should be
(e.g. "git clone --depth 5 git://some.where/repo.git").
Currently a shallow repository has number of limitations:
- Cloning and fetching _from_ a shallow clone are not
supported (nor tested -- so they might work by accident but
they are not expected to).
- Pushing from nor into a shallow clone are not expected to
work.
- Merging inside a shallow repository would work as long as a
merge base is found in the recent history, but otherwise it
will be like merging unrelated histories and may result in
huge conflicts.
but this would be more than adequate for people who want to
look at near the tip of a big project with a deep history and
send patches in e-mail format.
