Provided by: git-man_2.34.1-1ubuntu1.11_all 
NAME
gitfaq - Frequently asked questions about using Git
SYNOPSIS
gitfaq
DESCRIPTION
The examples in this FAQ assume a standard POSIX shell, like bash or dash, and a user, A U
Thor, who has the account author on the hosting provider git.example.org.
CONFIGURATION
What should I put in user.name?
You should put your personal name, generally a form using a given name and family
name. For example, the current maintainer of Git uses "Junio C Hamano". This will be
the name portion that is stored in every commit you make.
This configuration doesn’t have any effect on authenticating to remote services; for
that, see credential.username in git-config(1).
What does http.postBuffer really do?
This option changes the size of the buffer that Git uses when pushing data to a remote
over HTTP or HTTPS. If the data is larger than this size, libcurl, which handles the
HTTP support for Git, will use chunked transfer encoding since it isn’t known ahead of
time what the size of the pushed data will be.
Leaving this value at the default size is fine unless you know that either the remote
server or a proxy in the middle doesn’t support HTTP/1.1 (which introduced the chunked
transfer encoding) or is known to be broken with chunked data. This is often
(erroneously) suggested as a solution for generic push problems, but since almost
every server and proxy supports at least HTTP/1.1, raising this value usually doesn’t
solve most push problems. A server or proxy that didn’t correctly support HTTP/1.1 and
chunked transfer encoding wouldn’t be that useful on the Internet today, since it
would break lots of traffic.
Note that increasing this value will increase the memory used on every relevant push
that Git does over HTTP or HTTPS, since the entire buffer is allocated regardless of
whether or not it is all used. Thus, it’s best to leave it at the default unless you
are sure you need a different value.
How do I configure a different editor?
If you haven’t specified an editor specifically for Git, it will by default use the
editor you’ve configured using the VISUAL or EDITOR environment variables, or if
neither is specified, the system default (which is usually vi). Since some people find
vi difficult to use or prefer a different editor, it may be desirable to change the
editor used.
If you want to configure a general editor for most programs which need one, you can
edit your shell configuration (e.g., ~/.bashrc or ~/.zshenv) to contain a line setting
the EDITOR or VISUAL environment variable to an appropriate value. For example, if you
prefer the editor nano, then you could write the following:
export VISUAL=nano
If you want to configure an editor specifically for Git, you can either set the
core.editor configuration value or the GIT_EDITOR environment variable. You can see
git-var(1) for details on the order in which these options are consulted.
Note that in all cases, the editor value will be passed to the shell, so any arguments
containing spaces should be appropriately quoted. Additionally, if your editor
normally detaches from the terminal when invoked, you should specify it with an
argument that makes it not do that, or else Git will not see any changes. An example
of a configuration addressing both of these issues on Windows would be the
configuration "C:\Program Files\Vim\gvim.exe" --nofork, which quotes the filename with
spaces and specifies the --nofork option to avoid backgrounding the process.
CREDENTIALS
How do I specify my credentials when pushing over HTTP?
The easiest way to do this is to use a credential helper via the credential.helper
configuration. Most systems provide a standard choice to integrate with the system
credential manager. For example, Git for Windows provides the wincred credential
manager, macOS has the osxkeychain credential manager, and Unix systems with a
standard desktop environment can use the libsecret credential manager. All of these
store credentials in an encrypted store to keep your passwords or tokens secure.
In addition, you can use the store credential manager which stores in a file in your
home directory, or the cache credential manager, which does not permanently store your
credentials, but does prevent you from being prompted for them for a certain period of
time.
You can also just enter your password when prompted. While it is possible to place the
password (which must be percent-encoded) in the URL, this is not particularly secure
and can lead to accidental exposure of credentials, so it is not recommended.
How do I read a password or token from an environment variable?
The credential.helper configuration option can also take an arbitrary shell command
that produces the credential protocol on standard output. This is useful when passing
credentials into a container, for example.
Such a shell command can be specified by starting the option value with an exclamation
point. If your password or token were stored in the GIT_TOKEN, you could run the
following command to set your credential helper:
$ git config credential.helper \
'!f() { echo username=author; echo "password=$GIT_TOKEN"; };f'
How do I change the password or token I’ve saved in my credential manager?
Usually, if the password or token is invalid, Git will erase it and prompt for a new
one. However, there are times when this doesn’t always happen. To change the password
or token, you can erase the existing credentials and then Git will prompt for new
ones. To erase credentials, use a syntax like the following (substituting your
username and the hostname):
$ echo url=https://author@git.example.org | git credential reject
How do I use multiple accounts with the same hosting provider using HTTP?
Usually the easiest way to distinguish between these accounts is to use the username
in the URL. For example, if you have the accounts author and committer on
git.example.org, you can use the URLs https://author@git.example.org/org1/project1.git
and https://committer@git.example.org/org2/project2.git. This way, when you use a
credential helper, it will automatically try to look up the correct credentials for
your account. If you already have a remote set up, you can change the URL with
something like git remote set-url origin
https://author@git.example.org/org1/project1.git (see git-remote(1) for details).
How do I use multiple accounts with the same hosting provider using SSH?
With most hosting providers that support SSH, a single key pair uniquely identifies a
user. Therefore, to use multiple accounts, it’s necessary to create a key pair for
each account. If you’re using a reasonably modern OpenSSH version, you can create a
new key pair with something like ssh-keygen -t ed25519 -f ~/.ssh/id_committer. You can
then register the public key (in this case, ~/.ssh/id_committer.pub; note the .pub)
with the hosting provider.
Most hosting providers use a single SSH account for pushing; that is, all users push
to the git account (e.g., git@git.example.org). If that’s the case for your provider,
you can set up multiple aliases in SSH to make it clear which key pair to use. For
example, you could write something like the following in ~/.ssh/config, substituting
the proper private key file:
# This is the account for author on git.example.org.
Host example_author
HostName git.example.org
User git
# This is the key pair registered for author with git.example.org.
IdentityFile ~/.ssh/id_author
IdentitiesOnly yes
# This is the account for committer on git.example.org.
Host example_committer
HostName git.example.org
User git
# This is the key pair registered for committer with git.example.org.
IdentityFile ~/.ssh/id_committer
IdentitiesOnly yes
Then, you can adjust your push URL to use git@example_author or git@example_committer
instead of git@example.org (e.g., git remote set-url
git@example_author:org1/project1.git).
COMMON ISSUES
I’ve made a mistake in the last commit. How do I change it?
You can make the appropriate change to your working tree, run git add <file> or git rm
<file>, as appropriate, to stage it, and then git commit --amend. Your change will be
included in the commit, and you’ll be prompted to edit the commit message again; if
you wish to use the original message verbatim, you can use the --no-edit option to git
commit in addition, or just save and quit when your editor opens.
I’ve made a change with a bug and it’s been included in the main branch. How should I undo
it?
The usual way to deal with this is to use git revert. This preserves the history that
the original change was made and was a valuable contribution, but also introduces a
new commit that undoes those changes because the original had a problem. The commit
message of the revert indicates the commit which was reverted and is usually edited to
include an explanation as to why the revert was made.
How do I ignore changes to a tracked file?
Git doesn’t provide a way to do this. The reason is that if Git needs to overwrite
this file, such as during a checkout, it doesn’t know whether the changes to the file
are precious and should be kept, or whether they are irrelevant and can safely be
destroyed. Therefore, it has to take the safe route and always preserve them.
It’s tempting to try to use certain features of git update-index, namely the
assume-unchanged and skip-worktree bits, but these don’t work properly for this
purpose and shouldn’t be used this way.
If your goal is to modify a configuration file, it can often be helpful to have a file
checked into the repository which is a template or set of defaults which can then be
copied alongside and modified as appropriate. This second, modified file is usually
ignored to prevent accidentally committing it.
I asked Git to ignore various files, yet they are still tracked
A gitignore file ensures that certain file(s) which are not tracked by Git remain
untracked. However, sometimes particular file(s) may have been tracked before adding
them into the .gitignore, hence they still remain tracked. To untrack and ignore
files/patterns, use git rm --cached <file/pattern> and add a pattern to .gitignore
that matches the <file>. See gitignore(5) for details.
How do I know if I want to do a fetch or a pull?
A fetch stores a copy of the latest changes from the remote repository, without
modifying the working tree or current branch. You can then at your leisure inspect,
merge, rebase on top of, or ignore the upstream changes. A pull consists of a fetch
followed immediately by either a merge or rebase. See git-pull(1).
MERGING AND REBASING
What kinds of problems can occur when merging long-lived branches with squash merges?
In general, there are a variety of problems that can occur when using squash merges to
merge two branches multiple times. These can include seeing extra commits in git log
output, with a GUI, or when using the ... notation to express a range, as well as the
possibility of needing to re-resolve conflicts again and again.
When Git does a normal merge between two branches, it considers exactly three points:
the two branches and a third commit, called the merge base, which is usually the
common ancestor of the commits. The result of the merge is the sum of the changes
between the merge base and each head. When you merge two branches with a regular merge
commit, this results in a new commit which will end up as a merge base when they’re
merged again, because there is now a new common ancestor. Git doesn’t have to consider
changes that occurred before the merge base, so you don’t have to re-resolve any
conflicts you resolved before.
When you perform a squash merge, a merge commit isn’t created; instead, the changes
from one side are applied as a regular commit to the other side. This means that the
merge base for these branches won’t have changed, and so when Git goes to perform its
next merge, it considers all of the changes that it considered the last time plus the
new changes. That means any conflicts may need to be re-resolved. Similarly, anything
using the ... notation in git diff, git log, or a GUI will result in showing all of
the changes since the original merge base.
As a consequence, if you want to merge two long-lived branches repeatedly, it’s best
to always use a regular merge commit.
If I make a change on two branches but revert it on one, why does the merge of those
branches include the change?
By default, when Git does a merge, it uses a strategy called the ort strategy, which
does a fancy three-way merge. In such a case, when Git performs the merge, it
considers exactly three points: the two heads and a third point, called the merge
base, which is usually the common ancestor of those commits. Git does not consider the
history or the individual commits that have happened on those branches at all.
As a result, if both sides have a change and one side has reverted that change, the
result is to include the change. This is because the code has changed on one side and
there is no net change on the other, and in this scenario, Git adopts the change.
If this is a problem for you, you can do a rebase instead, rebasing the branch with
the revert onto the other branch. A rebase in this scenario will revert the change,
because a rebase applies each individual commit, including the revert. Note that
rebases rewrite history, so you should avoid rebasing published branches unless you’re
sure you’re comfortable with that. See the NOTES section in git-rebase(1) for more
details.
HOOKS
How do I use hooks to prevent users from making certain changes?
The only safe place to make these changes is on the remote repository (i.e., the Git
server), usually in the pre-receive hook or in a continuous integration (CI) system.
These are the locations in which policy can be enforced effectively.
It’s common to try to use pre-commit hooks (or, for commit messages, commit-msg hooks)
to check these things, which is great if you’re working as a solo developer and want
the tooling to help you. However, using hooks on a developer machine is not effective
as a policy control because a user can bypass these hooks with --no-verify without
being noticed (among various other ways). Git assumes that the user is in control of
their local repositories and doesn’t try to prevent this or tattle on the user.
In addition, some advanced users find pre-commit hooks to be an impediment to
workflows that use temporary commits to stage work in progress or that create fixup
commits, so it’s better to push these kinds of checks to the server anyway.
CROSS-PLATFORM ISSUES
I’m on Windows and my text files are detected as binary.
Git works best when you store text files as UTF-8. Many programs on Windows support
UTF-8, but some do not and only use the little-endian UTF-16 format, which Git detects
as binary. If you can’t use UTF-8 with your programs, you can specify a working tree
encoding that indicates which encoding your files should be checked out with, while
still storing these files as UTF-8 in the repository. This allows tools like git-
diff(1) to work as expected, while still allowing your tools to work.
To do so, you can specify a gitattributes(5) pattern with the working-tree-encoding
attribute. For example, the following pattern sets all C files to use UTF-16LE-BOM,
which is a common encoding on Windows:
*.c working-tree-encoding=UTF-16LE-BOM
You will need to run git add --renormalize to have this take effect. Note that if you
are making these changes on a project that is used across platforms, you’ll probably
want to make it in a per-user configuration file or in the one in
$GIT_DIR/info/attributes, since making it in a .gitattributes file in the repository
will apply to all users of the repository.
See the following entry for information about normalizing line endings as well, and
see gitattributes(5) for more information about attribute files.
I’m on Windows and git diff shows my files as having a ^M at the end.
By default, Git expects files to be stored with Unix line endings. As such, the
carriage return (^M) that is part of a Windows line ending is shown because it is
considered to be trailing whitespace. Git defaults to showing trailing whitespace only
on new lines, not existing ones.
You can store the files in the repository with Unix line endings and convert them
automatically to your platform’s line endings. To do that, set the configuration
option core.eol to native and see the following entry for information about how to
configure files as text or binary.
You can also control this behavior with the core.whitespace setting if you don’t wish
to remove the carriage returns from your line endings.
Why do I have a file that’s always modified?
Internally, Git always stores file names as sequences of bytes and doesn’t perform any
encoding or case folding. However, Windows and macOS by default both perform case
folding on file names. As a result, it’s possible to end up with multiple files or
directories whose names differ only in case. Git can handle this just fine, but the
file system can store only one of these files, so when Git reads the other file to see
its contents, it looks modified.
It’s best to remove one of the files such that you only have one file. You can do this
with commands like the following (assuming two files AFile.txt and afile.txt) on an
otherwise clean working tree:
$ git rm --cached AFile.txt
$ git commit -m 'Remove files conflicting in case'
$ git checkout .
This avoids touching the disk, but removes the additional file. Your project may
prefer to adopt a naming convention, such as all-lowercase names, to avoid this
problem from occurring again; such a convention can be checked using a pre-receive
hook or as part of a continuous integration (CI) system.
It is also possible for perpetually modified files to occur on any platform if a
smudge or clean filter is in use on your system but a file was previously committed
without running the smudge or clean filter. To fix this, run the following on an
otherwise clean working tree:
$ git add --renormalize .
What’s the recommended way to store files in Git?
While Git can store and handle any file of any type, there are some settings that work
better than others. In general, we recommend that text files be stored in UTF-8
without a byte-order mark (BOM) with LF (Unix-style) endings. We also recommend the
use of UTF-8 (again, without BOM) in commit messages. These are the settings that work
best across platforms and with tools such as git diff and git merge.
Additionally, if you have a choice between storage formats that are text based or
non-text based, we recommend storing files in the text format and, if necessary,
transforming them into the other format. For example, a text-based SQL dump with one
record per line will work much better for diffing and merging than an actual database
file. Similarly, text-based formats such as Markdown and AsciiDoc will work better
than binary formats such as Microsoft Word and PDF.
Similarly, storing binary dependencies (e.g., shared libraries or JAR files) or build
products in the repository is generally not recommended. Dependencies and build
products are best stored on an artifact or package server with only references, URLs,
and hashes stored in the repository.
We also recommend setting a gitattributes(5) file to explicitly mark which files are
text and which are binary. If you want Git to guess, you can set the attribute
text=auto. For example, the following might be appropriate in some projects:
# By default, guess.
* text=auto
# Mark all C files as text.
*.c text
# Mark all JPEG files as binary.
*.jpg binary
These settings help tools pick the right format for output such as patches and result
in files being checked out in the appropriate line ending for the platform.
GIT
Part of the git(1) suite