GIT-PULL(1) Git Manual GIT-PULL(1)
NAME
git-pull - Fetch from and integrate with another repository or a local
branch
SYNOPSIS
git pull [<options>] [<repository> [<refspec>...]]
DESCRIPTION
Incorporates changes from a remote repository into the current branch.
In its default mode, git pull is shorthand for git fetch followed by
git merge FETCH_HEAD.
More precisely, git pull runs git fetch with the given parameters and
calls git merge to merge the retrieved branch heads into the current
branch. With --rebase, it runs git rebase instead of git merge.
<repository> should be the name of a remote repository as passed to
git-fetch(1). <refspec> can name an arbitrary remote ref (for example,
the name of a tag) or even a collection of refs with corresponding
remote-tracking branches (e.g., refs/heads/*:refs/remotes/origin/*),
but usually it is the name of a branch in the remote repository.
Default values for <repository> and <branch> are read from the "remote"
and "merge" configuration for the current branch as set by git-
branch(1) --track.
Assume the following history exists and the current branch is "master":
A---B---C master on origin
/
D---E---F---G master
^
origin/master in your repository
Then "git pull" will fetch and replay the changes from the remote
master branch since it diverged from the local master (i.e., E) until
its current commit (C) on top of master and record the result in a new
commit along with the names of the two parent commits and a log message
from the user describing the changes.
A---B---C origin/master
/ \
D---E---F---G---H master
See git-merge(1) for details, including how conflicts are presented and
handled.
In Git 1.7.0 or later, to cancel a conflicting merge, use git reset
--merge. Warning: In older versions of Git, running git pull with
uncommitted changes is discouraged: while possible, it leaves you in a
state that may be hard to back out of in the case of a conflict.
If any of the remote changes overlap with local uncommitted changes,
the merge will be automatically canceled and the work tree untouched.
It is generally best to get any local changes in working order before
pulling or stash them away with git-stash(1).
OPTIONS
-q, --quiet
This is passed to both underlying git-fetch to squelch reporting of
during transfer, and underlying git-merge to squelch output during
merging.
-v, --verbose
Pass --verbose to git-fetch and git-merge.
--[no-]recurse-submodules[=yes|on-demand|no]
This option controls if new commits of populated submodules should
be fetched, and if the working trees of active submodules should be
updated, too (see git-fetch(1), git-config(1) and gitmodules(5)).
If the checkout is done via rebase, local submodule commits are
rebased as well.
If the update is done via merge, the submodule conflicts are
resolved and checked out.
Options related to merging
--commit, --no-commit
Perform the merge and commit the result. This option can be used to
override --no-commit.
With --no-commit perform the merge and stop just before creating a
merge commit, to give the user a chance to inspect and further
tweak the merge result before committing.
Note that fast-forward updates do not create a merge commit and
therefore there is no way to stop those merges with --no-commit.
Thus, if you want to ensure your branch is not changed or updated
by the merge command, use --no-ff with --no-commit.
--edit, -e, --no-edit
Invoke an editor before committing successful mechanical merge to
further edit the auto-generated merge message, so that the user can
explain and justify the merge. The --no-edit option can be used to
accept the auto-generated message (this is generally discouraged).
Older scripts may depend on the historical behaviour of not
allowing the user to edit the merge log message. They will see an
editor opened when they run git merge. To make it easier to adjust
such scripts to the updated behaviour, the environment variable
GIT_MERGE_AUTOEDIT can be set to no at the beginning of them.
--cleanup=<mode>
This option determines how the merge message will be cleaned up
before committing. See git-commit(1) for more details. In addition,
if the <mode> is given a value of scissors, scissors will be
appended to MERGE_MSG before being passed on to the commit
machinery in the case of a merge conflict.
--ff, --no-ff, --ff-only
Specifies how a merge is handled when the merged-in history is
already a descendant of the current history. --ff is the default
unless merging an annotated (and possibly signed) tag that is not
stored in its natural place in the refs/tags/ hierarchy, in which
case --no-ff is assumed.
With --ff, when possible resolve the merge as a fast-forward (only
update the branch pointer to match the merged branch; do not create
a merge commit). When not possible (when the merged-in history is
not a descendant of the current history), create a merge commit.
With --no-ff, create a merge commit in all cases, even when the
merge could instead be resolved as a fast-forward.
With --ff-only, resolve the merge as a fast-forward when possible.
When not possible, refuse to merge and exit with a non-zero status.
-S[<keyid>], --gpg-sign[=<keyid>], --no-gpg-sign
GPG-sign the resulting merge commit. The keyid argument is optional
and defaults to the committer identity; if specified, it must be
stuck to the option without a space. --no-gpg-sign is useful to
countermand both commit.gpgSign configuration variable, and earlier
--gpg-sign.
--log[=<n>], --no-log
In addition to branch names, populate the log message with one-line
descriptions from at most <n> actual commits that are being merged.
See also git-fmt-merge-msg(1).
With --no-log do not list one-line descriptions from the actual
commits being merged.
--signoff, --no-signoff
Add Signed-off-by line by the committer at the end of the commit
log message. The meaning of a signoff depends on the project, but
it typically certifies that committer has the rights to submit this
work under the same license and agrees to a Developer Certificate
of Origin (see http://developercertificate.org/ for more
information).
With --no-signoff do not add a Signed-off-by line.
--stat, -n, --no-stat
Show a diffstat at the end of the merge. The diffstat is also
controlled by the configuration option merge.stat.
With -n or --no-stat do not show a diffstat at the end of the
merge.
--squash, --no-squash
Produce the working tree and index state as if a real merge
happened (except for the merge information), but do not actually
make a commit, move the HEAD, or record $GIT_DIR/MERGE_HEAD (to
cause the next git commit command to create a merge commit). This
allows you to create a single commit on top of the current branch
whose effect is the same as merging another branch (or more in case
of an octopus).
With --no-squash perform the merge and commit the result. This
option can be used to override --squash.
With --squash, --commit is not allowed, and will fail.
--no-verify
This option bypasses the pre-merge and commit-msg hooks. See also
githooks(5).
-s <strategy>, --strategy=<strategy>
Use the given merge strategy; can be supplied more than once to
specify them in the order they should be tried. If there is no -s
option, a built-in list of strategies is used instead (git
merge-recursive when merging a single head, git merge-octopus
otherwise).
-X <option>, --strategy-option=<option>
Pass merge strategy specific option through to the merge strategy.
--verify-signatures, --no-verify-signatures
Verify that the tip commit of the side branch being merged is
signed with a valid key, i.e. a key that has a valid uid: in the
default trust model, this means the signing key has been signed by
a trusted key. If the tip commit of the side branch is not signed
with a valid key, the merge is aborted.
--summary, --no-summary
Synonyms to --stat and --no-stat; these are deprecated and will be
removed in the future.
--autostash, --no-autostash
Automatically create a temporary stash entry before the operation
begins, and apply it after the operation ends. This means that you
can run the operation on a dirty worktree. However, use with care:
the final stash application after a successful merge might result
in non-trivial conflicts.
--allow-unrelated-histories
By default, git merge command refuses to merge histories that do
not share a common ancestor. This option can be used to override
this safety when merging histories of two projects that started
their lives independently. As that is a very rare occasion, no
configuration variable to enable this by default exists and will
not be added.
-r, --rebase[=false|true|merges|preserve|interactive]
When true, rebase the current branch on top of the upstream branch
after fetching. If there is a remote-tracking branch corresponding
to the upstream branch and the upstream branch was rebased since
last fetched, the rebase uses that information to avoid rebasing
non-local changes.
When set to merges, rebase using git rebase --rebase-merges so that
the local merge commits are included in the rebase (see git-
rebase(1) for details).
When set to preserve (deprecated in favor of merges), rebase with
the --preserve-merges option passed to git rebase so that locally
created merge commits will not be flattened.
When false, merge the current branch into the upstream branch.
When interactive, enable the interactive mode of rebase.
See pull.rebase, branch.<name>.rebase and branch.autoSetupRebase in
git-config(1) if you want to make git pull always use --rebase
instead of merging.
Note
This is a potentially dangerous mode of operation. It rewrites
history, which does not bode well when you published that
history already. Do not use this option unless you have read
git-rebase(1) carefully.
--no-rebase
Override earlier --rebase.
Options related to fetching
--all
Fetch all remotes.
-a, --append
Append ref names and object names of fetched refs to the existing
contents of .git/FETCH_HEAD. Without this option old data in
.git/FETCH_HEAD will be overwritten.
--depth=<depth>
Limit fetching to the specified number of commits from the tip of
each remote branch history. If fetching to a shallow repository
created by git clone with --depth=<depth> option (see git-
clone(1)), deepen or shorten the history to the specified number of
commits. Tags for the deepened commits are not fetched.
--deepen=<depth>
Similar to --depth, except it specifies the number of commits from
the current shallow boundary instead of from the tip of each remote
branch history.
--shallow-since=<date>
Deepen or shorten the history of a shallow repository to include
all reachable commits after <date>.
--shallow-exclude=<revision>
Deepen or shorten the history of a shallow repository to exclude
commits reachable from a specified remote branch or tag. This
option can be specified multiple times.
--unshallow
If the source repository is complete, convert a shallow repository
to a complete one, removing all the limitations imposed by shallow
repositories.
If the source repository is shallow, fetch as much as possible so
that the current repository has the same history as the source
repository.
--update-shallow
By default when fetching from a shallow repository, git fetch
refuses refs that require updating .git/shallow. This option
updates .git/shallow and accept such refs.
--negotiation-tip=<commit|glob>
By default, Git will report, to the server, commits reachable from
all local refs to find common commits in an attempt to reduce the
size of the to-be-received packfile. If specified, Git will only
report commits reachable from the given tips. This is useful to
speed up fetches when the user knows which local ref is likely to
have commits in common with the upstream ref being fetched.
This option may be specified more than once; if so, Git will report
commits reachable from any of the given commits.
The argument to this option may be a glob on ref names, a ref, or
the (possibly abbreviated) SHA-1 of a commit. Specifying a glob is
equivalent to specifying this option multiple times, one for each
matching ref name.
See also the fetch.negotiationAlgorithm configuration variable
documented in git-config(1).
--dry-run
Show what would be done, without making any changes.
-f, --force
When git fetch is used with <src>:<dst> refspec it may refuse to
update the local branch as discussed in the <refspec> part of the
git-fetch(1) documentation. This option overrides that check.
-k, --keep
Keep downloaded pack.
-p, --prune
Before fetching, remove any remote-tracking references that no
longer exist on the remote. Tags are not subject to pruning if they
are fetched only because of the default tag auto-following or due
to a --tags option. However, if tags are fetched due to an explicit
refspec (either on the command line or in the remote configuration,
for example if the remote was cloned with the --mirror option),
then they are also subject to pruning. Supplying --prune-tags is a
shorthand for providing the tag refspec.
--no-tags
By default, tags that point at objects that are downloaded from the
remote repository are fetched and stored locally. This option
disables this automatic tag following. The default behavior for a
remote may be specified with the remote.<name>.tagOpt setting. See
git-config(1).
--refmap=<refspec>
When fetching refs listed on the command line, use the specified
refspec (can be given more than once) to map the refs to
remote-tracking branches, instead of the values of remote.*.fetch
configuration variables for the remote repository. Providing an
empty <refspec> to the --refmap option causes Git to ignore the
configured refspecs and rely entirely on the refspecs supplied as
command-line arguments. See section on "Configured Remote-tracking
Branches" for details.
-t, --tags
Fetch all tags from the remote (i.e., fetch remote tags refs/tags/*
into local tags with the same name), in addition to whatever else
would otherwise be fetched. Using this option alone does not
subject tags to pruning, even if --prune is used (though tags may
be pruned anyway if they are also the destination of an explicit
refspec; see --prune).
-j, --jobs=<n>
Number of parallel children to be used for all forms of fetching.
If the --multiple option was specified, the different remotes will
be fetched in parallel. If multiple submodules are fetched, they
will be fetched in parallel. To control them independently, use the
config settings fetch.parallel and submodule.fetchJobs (see git-
config(1)).
Typically, parallel recursive and multi-remote fetches will be
faster. By default fetches are performed sequentially, not in
parallel.
--set-upstream
If the remote is fetched successfully, pull and add upstream
(tracking) reference, used by argument-less git-pull(1) and other
commands. For more information, see branch.<name>.merge and
branch.<name>.remote in git-config(1).
--upload-pack <upload-pack>
When given, and the repository to fetch from is handled by git
fetch-pack, --exec=<upload-pack> is passed to the command to
specify non-default path for the command run on the other end.
--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.
-o <option>, --server-option=<option>
Transmit the given string to the server when communicating using
protocol version 2. The given string must not contain a NUL or LF
character. The server's handling of server options, including
unknown ones, is server-specific. When multiple
--server-option=<option> are given, they are all sent to the other
side in the order listed on the command line.
--show-forced-updates
By default, git checks if a branch is force-updated during fetch.
This can be disabled through fetch.showForcedUpdates, but the
--show-forced-updates option guarantees this check occurs. See git-
config(1).
--no-show-forced-updates
By default, git checks if a branch is force-updated during fetch.
Pass --no-show-forced-updates or set fetch.showForcedUpdates to
false to skip this check for performance reasons. If used during
git-pull the --ff-only option will still check for forced updates
before attempting a fast-forward update. See git-config(1).
-4, --ipv4
Use IPv4 addresses only, ignoring IPv6 addresses.
-6, --ipv6
Use IPv6 addresses only, ignoring IPv4 addresses.
<repository>
The "remote" repository that is the source of a fetch or pull
operation. This parameter can be either a URL (see the section GIT
URLS below) or the name of a remote (see the section REMOTES
below).
<refspec>
Specifies which refs to fetch and which local refs to update. When
no <refspec>s appear on the command line, the refs to fetch are
read from remote.<repository>.fetch variables instead (see the
section "CONFIGURED REMOTE-TRACKING BRANCHES" in git-fetch(1)).
The format of a <refspec> parameter is an optional plus +, followed
by the source <src>, followed by a colon :, followed by the
destination ref <dst>. The colon can be omitted when <dst> is
empty. <src> is typically a ref, but it can also be a fully spelled
hex object name.
tag <tag> means the same as refs/tags/<tag>:refs/tags/<tag>; it
requests fetching everything up to the given tag.
The remote ref that matches <src> is fetched, and if <dst> is not
an empty string, an attempt is made to update the local ref that
matches it.
Whether that update is allowed without --force depends on the ref
namespace it's being fetched to, the type of object being fetched,
and whether the update is considered to be a fast-forward.
Generally, the same rules apply for fetching as when pushing, see
the <refspec>... section of git-push(1) for what those are.
Exceptions to those rules particular to git fetch are noted below.
Until Git version 2.20, and unlike when pushing with git-push(1),
any updates to refs/tags/* would be accepted without + in the
refspec (or --force). When fetching, we promiscuously considered
all tag updates from a remote to be forced fetches. Since Git
version 2.20, fetching to update refs/tags/* works the same way as
when pushing. I.e. any updates will be rejected without + in the
refspec (or --force).
Unlike when pushing with git-push(1), any updates outside of
refs/{tags,heads}/* will be accepted without + in the refspec (or
--force), whether that's swapping e.g. a tree object for a blob, or
a commit for another commit that's doesn't have the previous commit
as an ancestor etc.
Unlike when pushing with git-push(1), there is no configuration
which'll amend these rules, and nothing like a pre-fetch hook
analogous to the pre-receive hook.
As with pushing with git-push(1), all of the rules described above
about what's not allowed as an update can be overridden by adding
an the optional leading + to a refspec (or using --force command
line option). The only exception to this is that no amount of
forcing will make the refs/heads/* namespace accept a non-commit
object.
Note
When the remote branch you want to fetch is known to be rewound
and rebased regularly, it is expected that its new tip will not
be descendant of its previous tip (as stored in your
remote-tracking branch the last time you fetched). You would
want to use the + sign to indicate non-fast-forward updates
will be needed for such branches. There is no way to determine
or declare that a branch will be made available in a repository
with this behavior; the pulling user simply must know this is
the expected usage pattern for a branch.
Note
There is a difference between listing multiple <refspec>
directly on git pull command line and having multiple
remote.<repository>.fetch entries in your configuration for a
<repository> and running a git pull command without any
explicit <refspec> parameters. <refspec>s listed explicitly on
the command line are always merged into the current branch
after fetching. In other words, if you list more than one
remote ref, git pull will create an Octopus merge. On the other
hand, if you do not list any explicit <refspec> parameter on
the command line, git pull will fetch all the <refspec>s it
finds in the remote.<repository>.fetch configuration and merge
only the first <refspec> found into the current branch. This is
because making an Octopus from remote refs is rarely done,
while keeping track of multiple remote heads in one-go by
fetching more than one is often useful.
GIT URLS
In general, URLs contain information about the transport protocol, the
address of the remote server, and the path to the repository. Depending
on the transport protocol, some of this information may be absent.
Git supports ssh, git, http, and https protocols (in addition, ftp, and
ftps can be used for fetching, but this is inefficient and deprecated;
do not use it).
The native transport (i.e. git:// URL) does no authentication and
should be used with caution on unsecured networks.
The following syntaxes may be used with them:
o ssh://[user@]host.xz[:port]/path/to/repo.git/
o git://host.xz[:port]/path/to/repo.git/
o http[s]://host.xz[:port]/path/to/repo.git/
o ftp[s]://host.xz[:port]/path/to/repo.git/
An alternative scp-like syntax may also be used with the ssh protocol:
o [user@]host.xz:path/to/repo.git/
This syntax is only recognized if there are no slashes before the first
colon. This helps differentiate a local path that contains a colon. For
example the local path foo:bar could be specified as an absolute path
or ./foo:bar to avoid being misinterpreted as an ssh url.
The ssh and git protocols additionally support ~username expansion:
o ssh://[user@]host.xz[:port]/~[user]/path/to/repo.git/
o git://host.xz[:port]/~[user]/path/to/repo.git/
o [user@]host.xz:/~[user]/path/to/repo.git/
For local repositories, also supported by Git natively, the following
syntaxes may be used:
o /path/to/repo.git/
o file:///path/to/repo.git/
These two syntaxes are mostly equivalent, except when cloning, when the
former implies --local option. See git-clone(1) for details.
git clone, git fetch and git pull, but not git push, will also accept a
suitable bundle file. See git-bundle(1).
When Git doesn't know how to handle a certain transport protocol, it
attempts to use the remote-<transport> remote helper, if one exists. To
explicitly request a remote helper, the following syntax may be used:
o <transport>::<address>
where <address> may be a path, a server and path, or an arbitrary
URL-like string recognized by the specific remote helper being invoked.
See gitremote-helpers(7) for details.
If there are a large number of similarly-named remote repositories and
you want to use a different format for them (such that the URLs you use
will be rewritten into URLs that work), you can create a configuration
section of the form:
[url "<actual url base>"]
insteadOf = <other url base>
For example, with this:
[url "git://git.host.xz/"]
insteadOf = host.xz:/path/to/
insteadOf = work:
a URL like "work:repo.git" or like "host.xz:/path/to/repo.git" will be
rewritten in any context that takes a URL to be
"git://git.host.xz/repo.git".
If you want to rewrite URLs for push only, you can create a
configuration section of the form:
[url "<actual url base>"]
pushInsteadOf = <other url base>
For example, with this:
[url "ssh://example.org/"]
pushInsteadOf = git://example.org/
a URL like "git://example.org/path/to/repo.git" will be rewritten to
"ssh://example.org/path/to/repo.git" for pushes, but pulls will still
use the original URL.
REMOTES
The name of one of the following can be used instead of a URL as
<repository> argument:
o a remote in the Git configuration file: $GIT_DIR/config,
o a file in the $GIT_DIR/remotes directory, or
o a file in the $GIT_DIR/branches directory.
All of these also allow you to omit the refspec from the command line
because they each contain a refspec which git will use by default.
Named remote in configuration file
You can choose to provide the name of a remote which you had previously
configured using git-remote(1), git-config(1) or even by a manual edit
to the $GIT_DIR/config file. The URL of this remote will be used to
access the repository. The refspec of this remote will be used by
default when you do not provide a refspec on the command line. The
entry in the config file would appear like this:
[remote "<name>"]
url = <url>
pushurl = <pushurl>
push = <refspec>
fetch = <refspec>
The <pushurl> is used for pushes only. It is optional and defaults to
<url>.
Named file in $GIT_DIR/remotes
You can choose to provide the name of a file in $GIT_DIR/remotes. The
URL in this file will be used to access the repository. The refspec in
this file will be used as default when you do not provide a refspec on
the command line. This file should have the following format:
URL: one of the above URL format
Push: <refspec>
Pull: <refspec>
Push: lines are used by git push and Pull: lines are used by git pull
and git fetch. Multiple Push: and Pull: lines may be specified for
additional branch mappings.
Named file in $GIT_DIR/branches
You can choose to provide the name of a file in $GIT_DIR/branches. The
URL in this file will be used to access the repository. This file
should have the following format:
<url>#<head>
<url> is required; #<head> is optional.
Depending on the operation, git will use one of the following refspecs,
if you don't provide one on the command line. <branch> is the name of
this file in $GIT_DIR/branches and <head> defaults to master.
git fetch uses:
refs/heads/<head>:refs/heads/<branch>
git push uses:
HEAD:refs/heads/<head>
MERGE STRATEGIES
The merge mechanism (git merge and git pull commands) allows the
backend merge strategies to be chosen with -s option. Some strategies
can also take their own options, which can be passed by giving
-X<option> arguments to git merge and/or git pull.
resolve
This can only resolve two heads (i.e. the current branch and
another branch you pulled from) using a 3-way merge algorithm. It
tries to carefully detect criss-cross merge ambiguities and is
considered generally safe and fast.
recursive
This can only resolve two heads using a 3-way merge algorithm. When
there is more than one common ancestor that can be used for 3-way
merge, it creates a merged tree of the common ancestors and uses
that as the reference tree for the 3-way merge. This has been
reported to result in fewer merge conflicts without causing
mismerges by tests done on actual merge commits taken from Linux
2.6 kernel development history. Additionally this can detect and
handle merges involving renames, but currently cannot make use of
detected copies. This is the default merge strategy when pulling or
merging one branch.
The recursive strategy can take the following options:
ours
This option forces conflicting hunks to be auto-resolved
cleanly by favoring our version. Changes from the other tree
that do not conflict with our side are reflected in the merge
result. For a binary file, the entire contents are taken from
our side.
This should not be confused with the ours merge strategy, which
does not even look at what the other tree contains at all. It
discards everything the other tree did, declaring our history
contains all that happened in it.
theirs
This is the opposite of ours; note that, unlike ours, there is
no theirs merge strategy to confuse this merge option with.
patience
With this option, merge-recursive spends a little extra time to
avoid mismerges that sometimes occur due to unimportant
matching lines (e.g., braces from distinct functions). Use this
when the branches to be merged have diverged wildly. See also
git-diff(1) --patience.
diff-algorithm=[patience|minimal|histogram|myers]
Tells merge-recursive to use a different diff algorithm, which
can help avoid mismerges that occur due to unimportant matching
lines (such as braces from distinct functions). See also git-
diff(1) --diff-algorithm.
ignore-space-change, ignore-all-space, ignore-space-at-eol,
ignore-cr-at-eol
Treats lines with the indicated type of whitespace change as
unchanged for the sake of a three-way merge. Whitespace changes
mixed with other changes to a line are not ignored. See also
git-diff(1) -b, -w, --ignore-space-at-eol, and
--ignore-cr-at-eol.
o If their version only introduces whitespace changes to a
line, our version is used;
o If our version introduces whitespace changes but their
version includes a substantial change, their version is
used;
o Otherwise, the merge proceeds in the usual way.
renormalize
This runs a virtual check-out and check-in of all three stages
of a file when resolving a three-way merge. This option is
meant to be used when merging branches with different clean
filters or end-of-line normalization rules. See "Merging
branches with differing checkin/checkout attributes" in
gitattributes(5) for details.
no-renormalize
Disables the renormalize option. This overrides the
merge.renormalize configuration variable.
no-renames
Turn off rename detection. This overrides the merge.renames
configuration variable. See also git-diff(1) --no-renames.
find-renames[=<n>]
Turn on rename detection, optionally setting the similarity
threshold. This is the default. This overrides the
merge.renames configuration variable. See also git-diff(1)
--find-renames.
rename-threshold=<n>
Deprecated synonym for find-renames=<n>.
subtree[=<path>]
This option is a more advanced form of subtree strategy, where
the strategy makes a guess on how two trees must be shifted to
match with each other when merging. Instead, the specified path
is prefixed (or stripped from the beginning) to make the shape
of two trees to match.
octopus
This resolves cases with more than two heads, but refuses to do a
complex merge that needs manual resolution. It is primarily meant
to be used for bundling topic branch heads together. This is the
default merge strategy when pulling or merging more than one
branch.
ours
This resolves any number of heads, but the resulting tree of the
merge is always that of the current branch head, effectively
ignoring all changes from all other branches. It is meant to be
used to supersede old development history of side branches. Note
that this is different from the -Xours option to the recursive
merge strategy.
subtree
This is a modified recursive strategy. When merging trees A and B,
if B corresponds to a subtree of A, B is first adjusted to match
the tree structure of A, instead of reading the trees at the same
level. This adjustment is also done to the common ancestor tree.
With the strategies that use 3-way merge (including the default,
recursive), if a change is made on both branches, but later reverted on
one of the branches, that change will be present in the merged result;
some people find this behavior confusing. It occurs because only the
heads and the merge base are considered when performing a merge, not
the individual commits. The merge algorithm therefore considers the
reverted change as no change at all, and substitutes the changed
version instead.
DEFAULT BEHAVIOUR
Often people use git pull without giving any parameter. Traditionally,
this has been equivalent to saying git pull origin. However, when
configuration branch.<name>.remote is present while on branch <name>,
that value is used instead of origin.
In order to determine what URL to use to fetch from, the value of the
configuration remote.<origin>.url is consulted and if there is not any
such variable, the value on the URL: line in $GIT_DIR/remotes/<origin>
is used.
In order to determine what remote branches to fetch (and optionally
store in the remote-tracking branches) when the command is run without
any refspec parameters on the command line, values of the configuration
variable remote.<origin>.fetch are consulted, and if there aren't any,
$GIT_DIR/remotes/<origin> is consulted and its Pull: lines are used. In
addition to the refspec formats described in the OPTIONS section, you
can have a globbing refspec that looks like this:
refs/heads/*:refs/remotes/origin/*
A globbing refspec must have a non-empty RHS (i.e. must store what were
fetched in remote-tracking branches), and its LHS and RHS must end with
/*. The above specifies that all remote branches are tracked using
remote-tracking branches in refs/remotes/origin/ hierarchy under the
same name.
The rule to determine which remote branch to merge after fetching is a
bit involved, in order not to break backward compatibility.
If explicit refspecs were given on the command line of git pull, they
are all merged.
When no refspec was given on the command line, then git pull uses the
refspec from the configuration or $GIT_DIR/remotes/<origin>. In such
cases, the following rules apply:
1. If branch.<name>.merge configuration for the current branch <name>
exists, that is the name of the branch at the remote site that is
merged.
2. If the refspec is a globbing one, nothing is merged.
3. Otherwise the remote branch of the first refspec is merged.
EXAMPLES
o Update the remote-tracking branches for the repository you cloned
from, then merge one of them into your current branch:
$ git pull
$ git pull origin
Normally the branch merged in is the HEAD of the remote repository,
but the choice is determined by the branch.<name>.remote and
branch.<name>.merge options; see git-config(1) for details.
o Merge into the current branch the remote branch next:
$ git pull origin next
This leaves a copy of next temporarily in FETCH_HEAD, and updates
the remote-tracking branch origin/next. The same can be done by
invoking fetch and merge:
$ git fetch origin
$ git merge origin/next
If you tried a pull which resulted in complex conflicts and would want
to start over, you can recover with git reset.
SECURITY
The fetch and push protocols are not designed to prevent one side from
stealing data from the other repository that was not intended to be
shared. If you have private data that you need to protect from a
malicious peer, your best option is to store it in another repository.
This applies to both clients and servers. In particular, namespaces on
a server are not effective for read access control; you should only
grant read access to a namespace to clients that you would trust with
read access to the entire repository.
The known attack vectors are as follows:
1. The victim sends "have" lines advertising the IDs of objects it has
that are not explicitly intended to be shared but can be used to
optimize the transfer if the peer also has them. The attacker
chooses an object ID X to steal and sends a ref to X, but isn't
required to send the content of X because the victim already has
it. Now the victim believes that the attacker has X, and it sends
the content of X back to the attacker later. (This attack is most
straightforward for a client to perform on a server, by creating a
ref to X in the namespace the client has access to and then
fetching it. The most likely way for a server to perform it on a
client is to "merge" X into a public branch and hope that the user
does additional work on this branch and pushes it back to the
server without noticing the merge.)
2. As in #1, the attacker chooses an object ID X to steal. The victim
sends an object Y that the attacker already has, and the attacker
falsely claims to have X and not Y, so the victim sends Y as a
delta against X. The delta reveals regions of X that are similar to
Y to the attacker.
BUGS
Using --recurse-submodules can only fetch new commits in already
checked out submodules right now. When e.g. upstream added a new
submodule in the just fetched commits of the superproject the submodule
itself cannot be fetched, making it impossible to check out that
submodule later without having to do a fetch again. This is expected to
be fixed in a future Git version.
SEE ALSO
git-fetch(1), git-merge(1), git-config(1)
GIT
Part of the git(1) suite
Git 2.27.0 06/01/2020 GIT-PULL(1)