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NAME | SYNOPSIS | DESCRIPTION | CONFIGURATION | CREDENTIALS | COMMON ISSUES | MERGING AND REBASING | HOOKS | CROSS-PLATFORM ISSUES | GIT | COLOPHON |
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GITFAQ(7) Git Manual GITFAQ(7)
gitfaq - Frequently asked questions about using Git
gitfaq
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.
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.
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).
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).
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.
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.
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.
Part of the git(1) suite
This page is part of the git (Git distributed version control
system) project. Information about the project can be found at
⟨http://git-scm.com/⟩. If you have a bug report for this manual
page, see ⟨http://git-scm.com/community⟩. This page was obtained
from the project's upstream Git repository
⟨https://github.com/git/git.git⟩ on 2024-06-14. (At that time,
the date of the most recent commit that was found in the
repository was 2024-06-12.) If you discover any rendering
problems in this HTML version of the page, or you believe there
is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
Git 2.45.2.492.gd63586 2024-06-12 GITFAQ(7)
Pages that refer to this page: git(1)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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