| 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`). |
| |
| Transfers |
| --------- |
| |
| [[sync-working-tree]] |
| How do I sync a working tree across systems?:: |
| First, decide whether you want to do this at all. Git works best when you |
| push or pull your work using the typical `git push` and `git fetch` commands |
| and isn't designed to share a working tree across systems. This is |
| potentially risky and in some cases can cause repository corruption or data |
| loss. |
| + |
| Usually, doing so will cause `git status` to need to re-read every file in the |
| working tree. Additionally, Git's security model does not permit sharing a |
| working tree across untrusted users, so it is only safe to sync a working tree |
| if it will only be used by a single user across all machines. |
| + |
| It is important not to use a cloud syncing service to sync any portion of a Git |
| repository, since this can cause corruption, such as missing objects, changed |
| or added files, broken refs, and a wide variety of other problems. These |
| services tend to sync file by file on a continuous basis and don't understand |
| the structure of a Git repository. This is especially bad if they sync the |
| repository in the middle of it being updated, since that is very likely to |
| cause incomplete or partial updates and therefore data loss. |
| + |
| An example of the kind of corruption that can occur is conflicts over the state |
| of refs, such that both sides end up with different commits on a branch that |
| the other doesn't have. This can result in important objects becoming |
| unreferenced and possibly pruned by `git gc`, causing data loss. |
| + |
| Therefore, it's better to push your work to either the other system or a central |
| server using the normal push and pull mechanism. However, this doesn't always |
| preserve important data, like stashes, so some people prefer to share a working |
| tree across systems. |
| + |
| If you do this, the recommended approach is to use `rsync -a --delete-after` |
| (ideally with an encrypted connection such as with `ssh`) on the root of |
| repository. You should ensure several things when you do this: |
| + |
| * If you have additional worktrees or a separate Git directory, they must be |
| synced at the same time as the main working tree and repository. |
| * You are comfortable with the destination directory being an exact copy of the |
| source directory, _deleting any data that is already there_. |
| * The repository (including all worktrees and the Git directory) is in a |
| quiescent state for the duration of the transfer (that is, no operations of |
| any sort are taking place on it, including background operations like `git |
| gc` and operations invoked by your editor). |
| + |
| Be aware that even with these recommendations, syncing in this way has some risk |
| since it bypasses Git's normal integrity checking for repositories, so having |
| backups is advised. You may also wish to do a `git fsck` to verify the |
| integrity of your data on the destination system after syncing. |
| |
| 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. |
| |
| [[files-in-gitignore-are-tracked]] |
| 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 linkgit:gitignore[5] for details. |
| |
| [[fetching-and-pulling]] |
| 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 linkgit:git-pull[1]. |
| |
| [[proxy]] |
| Can I use a proxy with Git?:: |
| Yes, Git supports the use of proxies. Git honors the standard `http_proxy`, |
| `https_proxy`, and `no_proxy` environment variables commonly used on Unix, and |
| it also can be configured with `http.proxy` and similar options for HTTPS (see |
| linkgit:git-config[1]). The `http.proxy` and related options can be |
| customized on a per-URL pattern basis. In addition, Git can in theory |
| function normally with transparent proxies that exist on the network. |
| + |
| For SSH, Git can support a proxy using OpenSSH's `ProxyCommand`. Commonly used |
| tools include `netcat` and `socat`. However, they must be configured not to |
| exit when seeing EOF on standard input, which usually means that `netcat` will |
| require `-q` and `socat` will require a timeout with something like `-t 10`. |
| This is required because the way the Git SSH server knows that no more requests |
| will be made is an EOF on standard input, but when that happens, the server may |
| not have yet processed the final request, so dropping the connection at that |
| point would interrupt that request. |
| + |
| An example configuration entry in `~/.ssh/config` with an HTTP proxy might look |
| like this: |
| + |
| ---- |
| Host git.example.org |
| User git |
| ProxyCommand socat -t 10 - PROXY:proxy.example.org:%h:%p,proxyport=8080 |
| ---- |
| + |
| Note that in all cases, for Git to work properly, the proxy must be completely |
| transparent. The proxy cannot modify, tamper with, or buffer the connection in |
| any way, or Git will almost certainly fail to work. Note that many proxies, |
| including many TLS middleboxes, Windows antivirus and firewall programs other |
| than Windows Defender and Windows Firewall, and filtering proxies fail to meet |
| this standard, and as a result end up breaking Git. Because of the many |
| reports of problems and their poor security history, we recommend against the |
| use of these classes of software and devices. |
| |
| Merging and Rebasing |
| -------------------- |
| |
| [[long-running-squash-merge]] |
| 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. |
| |
| [[merge-two-revert-one]] |
| 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 linkgit:git-rebase[1] for more details. |
| |
| 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 |
| <<recommended-storage-settings,the question on recommended storage settings>> |
| 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. |
| |
| [[always-modified-files-case]] |
| 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 . |
| ---- |
| |
| [[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`. |
| + |
| With text files, Git will generally ensure that LF endings are used in the |
| repository. The `core.autocrlf` and `core.eol` configuration variables specify |
| what line-ending convention is followed when any text file is checked out. You |
| can also use the `eol` attribute (e.g., `eol=crlf`) to override which files get |
| what line-ending treatment. |
| + |
| For example, generally shell files must have LF endings and batch files must |
| have CRLF endings, so the following might be appropriate in some projects: |
| + |
| ---- |
| # By default, guess. |
| * text=auto |
| # Mark all C files as text. |
| *.c text |
| # Ensure all shell files have LF endings and all batch files have CRLF |
| # endings in the working tree and both have LF in the repo. |
| *.sh text eol=lf |
| *.bat text eol=crlf |
| # 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 |