1GITFAQ(7) Git Manual GITFAQ(7)
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6 gitfaq - Frequently asked questions about using Git
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9 gitfaq
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12 The examples in this FAQ assume a standard POSIX shell, like bash or
13 dash, and a user, A U Thor, who has the account author on the hosting
14 provider git.example.org.
15
17 What should I put in user.name?
18 You should put your personal name, generally a form using a given
19 name and family name. For example, the current maintainer of Git
20 uses "Junio C Hamano". This will be the name portion that is stored
21 in every commit you make.
22 This configuration doesn’t have any effect on authenticating to
24 remote services; for that, see credential.username in git-
25 config(1).
26 What does http.postBuffer really do?
28 This option changes the size of the buffer that Git uses when
29 pushing data to a remote over HTTP or HTTPS. If the data is larger
30 than this size, libcurl, which handles the HTTP support for Git,
31 will use chunked transfer encoding since it isn’t known ahead of
32 time what the size of the pushed data will be.
33 Leaving this value at the default size is fine unless you know that
35 either the remote server or a proxy in the middle doesn’t support
36 HTTP/1.1 (which introduced the chunked transfer encoding) or is
37 known to be broken with chunked data. This is often (erroneously)
38 suggested as a solution for generic push problems, but since almost
39 every server and proxy supports at least HTTP/1.1, raising this
40 value usually doesn’t solve most push problems. A server or proxy
41 that didn’t correctly support HTTP/1.1 and chunked transfer
42 encoding wouldn’t be that useful on the Internet today, since it
43 would break lots of traffic.
44 Note that increasing this value will increase the memory used on
46 every relevant push that Git does over HTTP or HTTPS, since the
47 entire buffer is allocated regardless of whether or not it is all
48 used. Thus, it’s best to leave it at the default unless you are
49 sure you need a different value.
50 How do I configure a different editor?
52 If you haven’t specified an editor specifically for Git, it will by
53 default use the editor you’ve configured using the VISUAL or EDITOR
54 environment variables, or if neither is specified, the system
55 default (which is usually vi). Since some people find vi difficult
56 to use or prefer a different editor, it may be desirable to change
57 the editor used.
58 If you want to configure a general editor for most programs which
60 need one, you can edit your shell configuration (e.g., ~/.bashrc or
61 ~/.zshenv) to contain a line setting the EDITOR or VISUAL
62 environment variable to an appropriate value. For example, if you
63 prefer the editor nano, then you could write the following:
64 export VISUAL=nano
66 If you want to configure an editor specifically for Git, you can
68 either set the core.editor configuration value or the GIT_EDITOR
69 environment variable. You can see git-var(1) for details on the
70 order in which these options are consulted.
71 Note that in all cases, the editor value will be passed to the
73 shell, so any arguments containing spaces should be appropriately
74 quoted. Additionally, if your editor normally detaches from the
75 terminal when invoked, you should specify it with an argument that
76 makes it not do that, or else Git will not see any changes. An
77 example of a configuration addressing both of these issues on
78 Windows would be the configuration "C:\Program Files\Vim\gvim.exe"
79 --nofork, which quotes the filename with spaces and specifies the
80 --nofork option to avoid backgrounding the process.
81
83 How do I specify my credentials when pushing over HTTP?
84 The easiest way to do this is to use a credential helper via the
85 credential.helper configuration. Most systems provide a standard
86 choice to integrate with the system credential manager. For
87 example, Git for Windows provides the wincred credential manager,
88 macOS has the osxkeychain credential manager, and Unix systems with
89 a standard desktop environment can use the libsecret credential
90 manager. All of these store credentials in an encrypted store to
91 keep your passwords or tokens secure.
92 In addition, you can use the store credential manager which stores
94 in a file in your home directory, or the cache credential manager,
95 which does not permanently store your credentials, but does prevent
96 you from being prompted for them for a certain period of time.
97 You can also just enter your password when prompted. While it is
99 possible to place the password (which must be percent-encoded) in
100 the URL, this is not particularly secure and can lead to accidental
101 exposure of credentials, so it is not recommended.
102 How do I read a password or token from an environment variable?
104 The credential.helper configuration option can also take an
105 arbitrary shell command that produces the credential protocol on
106 standard output. This is useful when passing credentials into a
107 container, for example.
108 Such a shell command can be specified by starting the option value
110 with an exclamation point. If your password or token were stored in
111 the GIT_TOKEN, you could run the following command to set your
112 credential helper:
113 $ git config credential.helper \
115 '!f() { echo username=author; echo "password=$GIT_TOKEN"; };f'
116 How do I change the password or token I’ve saved in my credential
118 manager?
119 Usually, if the password or token is invalid, Git will erase it and
120 prompt for a new one. However, there are times when this doesn’t
121 always happen. To change the password or token, you can erase the
122 existing credentials and then Git will prompt for new ones. To
123 erase credentials, use a syntax like the following (substituting
124 your username and the hostname):
125 $ echo url=https://author@git.example.org | git credential reject
127 How do I use multiple accounts with the same hosting provider using
129 HTTP?
130 Usually the easiest way to distinguish between these accounts is to
131 use the username in the URL. For example, if you have the accounts
132 author and committer on git.example.org, you can use the URLs
133 https://author@git.example.org/org1/project1.git and
134 https://committer@git.example.org/org2/project2.git. This way, when
135 you use a credential helper, it will automatically try to look up
136 the correct credentials for your account. If you already have a
137 remote set up, you can change the URL with something like git
138 remote set-url origin
139 https://author@git.example.org/org1/project1.git (see git-remote(1)
140 for details).
141 How do I use multiple accounts with the same hosting provider using
143 SSH?
144 With most hosting providers that support SSH, a single key pair
145 uniquely identifies a user. Therefore, to use multiple accounts,
146 it’s necessary to create a key pair for each account. If you’re
147 using a reasonably modern OpenSSH version, you can create a new key
148 pair with something like ssh-keygen -t ed25519 -f
149 ~/.ssh/id_committer. You can then register the public key (in this
150 case, ~/.ssh/id_committer.pub; note the .pub) with the hosting
151 provider.
152 Most hosting providers use a single SSH account for pushing; that
154 is, all users push to the git account (e.g., git@git.example.org).
155 If that’s the case for your provider, you can set up multiple
156 aliases in SSH to make it clear which key pair to use. For example,
157 you could write something like the following in ~/.ssh/config,
158 substituting the proper private key file:
159 # This is the account for author on git.example.org.
161 Host example_author
162 HostName git.example.org
163 User git
164 # This is the key pair registered for author with git.example.org.
165 IdentityFile ~/.ssh/id_author
166 IdentitiesOnly yes
167 # This is the account for committer on git.example.org.
168 Host example_committer
169 HostName git.example.org
170 User git
171 # This is the key pair registered for committer with git.example.org.
172 IdentityFile ~/.ssh/id_committer
173 IdentitiesOnly yes
174 Then, you can adjust your push URL to use git@example_author or
176 git@example_committer instead of git@example.org (e.g., git remote
177 set-url git@example_author:org1/project1.git).
178
180 I’ve made a mistake in the last commit. How do I change it?
181 You can make the appropriate change to your working tree, run git
182 add <file> or git rm <file>, as appropriate, to stage it, and then
183 git commit --amend. Your change will be included in the commit, and
184 you’ll be prompted to edit the commit message again; if you wish to
185 use the original message verbatim, you can use the --no-edit option
186 to git commit in addition, or just save and quit when your editor
187 opens.
188 I’ve made a change with a bug and it’s been included in the main
190 branch. How should I undo it?
191 The usual way to deal with this is to use git revert. This
192 preserves the history that the original change was made and was a
193 valuable contribution, but also introduces a new commit that undoes
194 those changes because the original had a problem. The commit
195 message of the revert indicates the commit which was reverted and
196 is usually edited to include an explanation as to why the revert
197 was made.
198 How do I ignore changes to a tracked file?
200 Git doesn’t provide a way to do this. The reason is that if Git
201 needs to overwrite this file, such as during a checkout, it doesn’t
202 know whether the changes to the file are precious and should be
203 kept, or whether they are irrelevant and can safely be destroyed.
204 Therefore, it has to take the safe route and always preserve them.
205 It’s tempting to try to use certain features of git update-index,
207 namely the assume-unchanged and skip-worktree bits, but these don’t
208 work properly for this purpose and shouldn’t be used this way.
209 If your goal is to modify a configuration file, it can often be
211 helpful to have a file checked into the repository which is a
212 template or set of defaults which can then be copied alongside and
213 modified as appropriate. This second, modified file is usually
214 ignored to prevent accidentally committing it.
215 I asked Git to ignore various files, yet they are still tracked
217 A gitignore file ensures that certain file(s) which are not tracked
218 by Git remain untracked. However, sometimes particular file(s) may
219 have been tracked before adding them into the .gitignore, hence
220 they still remain tracked. To untrack and ignore files/patterns,
221 use git rm --cached <file/pattern> and add a pattern to .gitignore
222 that matches the <file>. See gitignore(5) for details.
223 How do I know if I want to do a fetch or a pull?
225 A fetch stores a copy of the latest changes from the remote
226 repository, without modifying the working tree or current branch.
227 You can then at your leisure inspect, merge, rebase on top of, or
228 ignore the upstream changes. A pull consists of a fetch followed
229 immediately by either a merge or rebase. See git-pull(1).
230
232 What kinds of problems can occur when merging long-lived branches with
233 squash merges?
234 In general, there are a variety of problems that can occur when
235 using squash merges to merge two branches multiple times. These can
236 include seeing extra commits in git log output, with a GUI, or when
237 using the ... notation to express a range, as well as the
238 possibility of needing to re-resolve conflicts again and again.
239 When Git does a normal merge between two branches, it considers
241 exactly three points: the two branches and a third commit, called
242 the merge base, which is usually the common ancestor of the
243 commits. The result of the merge is the sum of the changes between
244 the merge base and each head. When you merge two branches with a
245 regular merge commit, this results in a new commit which will end
246 up as a merge base when they’re merged again, because there is now
247 a new common ancestor. Git doesn’t have to consider changes that
248 occurred before the merge base, so you don’t have to re-resolve any
249 conflicts you resolved before.
250 When you perform a squash merge, a merge commit isn’t created;
252 instead, the changes from one side are applied as a regular commit
253 to the other side. This means that the merge base for these
254 branches won’t have changed, and so when Git goes to perform its
255 next merge, it considers all of the changes that it considered the
256 last time plus the new changes. That means any conflicts may need
257 to be re-resolved. Similarly, anything using the ... notation in
258 git diff, git log, or a GUI will result in showing all of the
259 changes since the original merge base.
260 As a consequence, if you want to merge two long-lived branches
262 repeatedly, it’s best to always use a regular merge commit.
263 If I make a change on two branches but revert it on one, why does the
265 merge of those branches include the change?
266 By default, when Git does a merge, it uses a strategy called the
267 recursive strategy, which does a fancy three-way merge. In such a
268 case, when Git performs the merge, it considers exactly three
269 points: the two heads and a third point, called the merge base,
270 which is usually the common ancestor of those commits. Git does not
271 consider the history or the individual commits that have happened
272 on those branches at all.
273 As a result, if both sides have a change and one side has reverted
275 that change, the result is to include the change. This is because
276 the code has changed on one side and there is no net change on the
277 other, and in this scenario, Git adopts the change.
278 If this is a problem for you, you can do a rebase instead, rebasing
280 the branch with the revert onto the other branch. A rebase in this
281 scenario will revert the change, because a rebase applies each
282 individual commit, including the revert. Note that rebases rewrite
283 history, so you should avoid rebasing published branches unless
284 you’re sure you’re comfortable with that. See the NOTES section in
285 git-rebase(1) for more details.
286
288 How do I use hooks to prevent users from making certain changes?
289 The only safe place to make these changes is on the remote
290 repository (i.e., the Git server), usually in the pre-receive hook
291 or in a continuous integration (CI) system. These are the locations
292 in which policy can be enforced effectively.
293 It’s common to try to use pre-commit hooks (or, for commit
295 messages, commit-msg hooks) to check these things, which is great
296 if you’re working as a solo developer and want the tooling to help
297 you. However, using hooks on a developer machine is not effective
298 as a policy control because a user can bypass these hooks with
299 --no-verify without being noticed (among various other ways). Git
300 assumes that the user is in control of their local repositories and
301 doesn’t try to prevent this or tattle on the user.
302 In addition, some advanced users find pre-commit hooks to be an
304 impediment to workflows that use temporary commits to stage work in
305 progress or that create fixup commits, so it’s better to push these
306 kinds of checks to the server anyway.
307
309 I’m on Windows and my text files are detected as binary.
310 Git works best when you store text files as UTF-8. Many programs on
311 Windows support UTF-8, but some do not and only use the
312 little-endian UTF-16 format, which Git detects as binary. If you
313 can’t use UTF-8 with your programs, you can specify a working tree
314 encoding that indicates which encoding your files should be checked
315 out with, while still storing these files as UTF-8 in the
316 repository. This allows tools like git-diff(1) to work as expected,
317 while still allowing your tools to work.
318 To do so, you can specify a gitattributes(5) pattern with the
320 working-tree-encoding attribute. For example, the following pattern
321 sets all C files to use UTF-16LE-BOM, which is a common encoding on
322 Windows:
323 *.c working-tree-encoding=UTF-16LE-BOM
325 You will need to run git add --renormalize to have this take
327 effect. Note that if you are making these changes on a project that
328 is used across platforms, you’ll probably want to make it in a
329 per-user configuration file or in the one in
330 $GIT_DIR/info/attributes, since making it in a .gitattributes file
331 in the repository will apply to all users of the repository.
332 See the following entry for information about normalizing line
334 endings as well, and see gitattributes(5) for more information
335 about attribute files.
336 I’m on Windows and git diff shows my files as having a ^M at the end.
338 By default, Git expects files to be stored with Unix line endings.
339 As such, the carriage return (^M) that is part of a Windows line
340 ending is shown because it is considered to be trailing whitespace.
341 Git defaults to showing trailing whitespace only on new lines, not
342 existing ones.
343 You can store the files in the repository with Unix line endings
345 and convert them automatically to your platform’s line endings. To
346 do that, set the configuration option core.eol to native and see
347 the following entry for information about how to configure files as
348 text or binary.
349 You can also control this behavior with the core.whitespace setting
351 if you don’t wish to remove the carriage returns from your line
352 endings.
353 Why do I have a file that’s always modified?
355 Internally, Git always stores file names as sequences of bytes and
356 doesn’t perform any encoding or case folding. However, Windows and
357 macOS by default both perform case folding on file names. As a
358 result, it’s possible to end up with multiple files or directories
359 whose names differ only in case. Git can handle this just fine, but
360 the file system can store only one of these files, so when Git
361 reads the other file to see its contents, it looks modified.
362 It’s best to remove one of the files such that you only have one
364 file. You can do this with commands like the following (assuming
365 two files AFile.txt and afile.txt) on an otherwise clean working
366 tree:
367 $ git rm --cached AFile.txt
369 $ git commit -m 'Remove files conflicting in case'
370 $ git checkout .
371 This avoids touching the disk, but removes the additional file.
373 Your project may prefer to adopt a naming convention, such as
374 all-lowercase names, to avoid this problem from occurring again;
375 such a convention can be checked using a pre-receive hook or as
376 part of a continuous integration (CI) system.
377 It is also possible for perpetually modified files to occur on any
379 platform if a smudge or clean filter is in use on your system but a
380 file was previously committed without running the smudge or clean
381 filter. To fix this, run the following on an otherwise clean
382 working tree:
383 $ git add --renormalize .
385 What’s the recommended way to store files in Git?
387 While Git can store and handle any file of any type, there are some
388 settings that work better than others. In general, we recommend
389 that text files be stored in UTF-8 without a byte-order mark (BOM)
390 with LF (Unix-style) endings. We also recommend the use of UTF-8
391 (again, without BOM) in commit messages. These are the settings
392 that work best across platforms and with tools such as git diff and
393 git merge.
394 Additionally, if you have a choice between storage formats that are
396 text based or non-text based, we recommend storing files in the
397 text format and, if necessary, transforming them into the other
398 format. For example, a text-based SQL dump with one record per line
399 will work much better for diffing and merging than an actual
400 database file. Similarly, text-based formats such as Markdown and
401 AsciiDoc will work better than binary formats such as Microsoft
402 Word and PDF.
403 Similarly, storing binary dependencies (e.g., shared libraries or
405 JAR files) or build products in the repository is generally not
406 recommended. Dependencies and build products are best stored on an
407 artifact or package server with only references, URLs, and hashes
408 stored in the repository.
409 We also recommend setting a gitattributes(5) file to explicitly
411 mark which files are text and which are binary. If you want Git to
412 guess, you can set the attribute text=auto. For example, the
413 following might be appropriate in some projects:
414 # By default, guess.
416 * text=auto
417 # Mark all C files as text.
418 *.c text
419 # Mark all JPEG files as binary.
420 *.jpg binary
421 These settings help tools pick the right format for output such as
423 patches and result in files being checked out in the appropriate
424 line ending for the platform.
425
427 Part of the git(1) suite
428Git 2.30.2 2021-03-08 GITFAQ(7)