gitfaq(7)

=========

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

-------------

[[user-name]]

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 linkgit:git-config[1].

[[http-postbuffer]]

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.

[[configure-editor]]

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 linkgit: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

-----------

[[http-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.

[[http-credentials-environment]]

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'

----

[[http-reset-credentials]]

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

----

[[multiple-accounts-http]]

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

linkgit:git-remote[1] for details).

[[multiple-accounts-ssh]]

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

-------------

[[last-commit-amend]]

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.

[[undo-previous-change]]

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.

[[ignore-tracked-files]]

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.

Hooks

-----

[[restrict-with-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

---------------------

[[windows-text-binary]]

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

linkgit:git-diff[1] to work as expected, while still allowing your tools

to work.

+

To do so, you can specify a linkgit: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 linkgit:gitattributes[5] for more information about attribute files.

[[windows-diff-control-m]]

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.

[[recommended-storage-settings]]

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 linkgit: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 linkgit:git[1] suite