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git_configuration

Git Configuration

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“So far, we’ve covered the basics of how Git works and how to use it, and we’ve introduced a number of developer tools that Git provides to help you use it easily and efficiently. In this chapter, we’ll see how you can make Git operate in a more customized fashion, by introducing several important Git configuration settings and the Git hooks system. With these tools, it’s easy to get Git to work exactly the way you, your company, or your group needs it to.

Git Configuration

As you read briefly in Getting Started (https://www.git-scm.com/book/en/v2/ch00/ch01-getting-started), you can specify Git configuration settings with the git config command. One of the first things you did was set up your name and email address:


Git Configuration on Windows

The location of the system and global gitconfig configuration files varies, depending on which environment (native Windows command, Windows shell or MSYS2 shell) you're using, and depending on which binary (Git for Windows versus native git). There's a logic to it, but it can be hard to figure out…

Git version 2 introduced a much easier method of finding where the git configuration files are stored, the –show-origin flag. This parameter tells you exactly where each of the configuration files can be found.

Retrieve the locations (and name value pairs) of all git configuration files:

Retrieve the location (and name value pairs) of the system git configuration file:

git config –list –system –show-origin Retrieve the unique locations of all git configuration files:

git config –list –show-origin | awk '{print $1}' | uniq Local Regardless from where you use git on Windows, the repository (local) configuration always resides at the same location, in the root directory of your repository: .git\config

You can check this configuration using

git config –list –local System The system configuration has also a fixed path on Windows, relative to the installation directory: etc\gitconfig

For msysGit: %ProgramFiles(x86)%\Git\etc\gitconfig For Git for Windows (64 bit): %ProgramFiles%\Git\mingw64\etc\gitconfig For MSYS2-native git: [MSYS2-install-path]\etc\gitconfig This configuration file can be read using

git config –list –system Global This is the tricky one. Basically, it depends on what the binary or environment considers the HOME directory.

When using the Windows command shell, batch scripts or Windows programs, HOME is %USERPROFILE% . The global config file will be read from %USERPROFILE%\.gitconfig

However, when you're using a (Bash) shell under MSYS2 or Cygwin, HOME under that shell is %HOME% . The global config file will be read from $HOME/.gitconfig

The global configuration file can be found on yet another location, for Windows programs that use their own HOME environment. Take Emacs (which uses magit) for example: When Emacs is started from a Windows command shell, it sets the HOME variable to %APPDATA% , which means that .gitconfig will reside in %APPDATA%\.gitconfig

This configuration file can be read using

git config –list –global So to recap, the global git configuration file can be found under what that application considers to be the HOME directory, in .gitconfig .

Workflow setup: Linking the global configuration In my workflow I symlink the various versions of the global configuration. The system configration stays independent. The file at %USERPROFILE%\.gitconfig is considered the master global file where you make all your changes.

Run this command from within a Windows command shell to create a symbolic link for the system and global file. Be careful, as this command deletes the current gitconfig file in your MSYS2 home directory, as well as the one in %APPDATA% . Moreover mklink doesn't expand variables, so you'll have to type in the expanded path yourself.

mklink /h %APPDATA%\.gitconfig %USERPROFILE%\.gitconfig mklink /h [MSYS2-install-path]\home\[username]\.gitconfig %USERPROFILE%\.gitconfig


Retrieve the locations (and name value pairs) of all git configuration files:

git config --list –show-origin

Now you’ll learn a few of the more interesting options that you can set in this manner to customize your Git usage.

First, a quick review: Git uses a series of Git configuration files to determine non-default behavior that you may want. The first place Git looks for these values is in the system-wide [path]/etc/gitconfig file, which contains settings that are applied to every user on the system and all of their repositories. If you pass the option –system to git config, it reads and writes from this file specifically.

The next place Git looks is the ~/.gitconfig (or ~/.config/git/config) file, which is specific to each user. You can make Git read and write to this file by passing the –global option.

Finally, Git looks for Git configuration values in the Git configuration file in the Git directory (.git/config) of whatever Git repository you’re currently using. These values are specific to that single repository, and represent passing the –local option to git config (e.g. git config --local. If you don’t specify which level you want to work with, this is the default.

Each of these “levels” (Git system, Git global, Git local) overwrites values in the previous level, so values in .git/config trump those in [path]/etc/gitconfig, for instance.

Fair Use Source: https://www.onwebsecurity.com/configuration/git-on-windows-location-of-global-configuration-file.html

Note

Git’s configuration files are plain-text, so you can also set these values by manually editing the Git config file and inserting the correct Git syntax. It’s generally easier to run the git config command, though.

Basic Client Configuration

The Git configuration options recognized by Git fall into two categories: Git client-side and Git server-side. The majority of the Git options are Git client-side — configuring your personal working Git preferences. Many, many Git configuration options are supported, but a large fraction of them are useful only in certain edge cases; we’ll cover just the most common and useful options here. If you want to see a list of all the options your version of Git recognizes, you can run:

$ man git-config

This command lists all the available options in quite a bit of detail. You can also find this Git reference material at https://git-scm.com/docs/git-config.

core.editor

Git core.editor

By default, Git uses whatever you’ve set as your default text editor via one of the shell environment variables VISUAL or EDITOR, or else falls back to the vi editor to create and edit your Git commit and Git tag messages. To change that Git default to something else, you can use the core.editor Git setting:

  • $ git config –global core.editor emacs

Now, no matter what is set as your default shell editor, Git will fire up Emacs to edit messages.

commit.template

Git commit.template

If you set this to the path of a file on your system, Git will use that file as the default initial message when you commit. The value in creating a custom commit template is that you can use it to remind yourself (or others) of the proper format and style when creating a commit message.

For instance, consider a template file at ~/.gitmessage.txt that looks like this:

Subject line (try to keep under 50 characters)

Multi-line description of commit, feel free to be detailed.

[Ticket: X] Note how this commit template reminds the committer to keep the subject line short (for the sake of git log –oneline output), to add further detail under that, and to refer to an issue or bug tracker ticket number if one exists.

To tell Git to use it as the default message that appears in your editor when you run git commit, set the commit.template configuration value:

$ git config –global commit.template ~/.gitmessage.txt $ git commit Then, your editor will open to something like this for your placeholder commit message when you commit:

Subject line (try to keep under 50 characters)

Multi-line description of commit, feel free to be detailed.

[Ticket: X]

  1. Please enter the commit message for your changes. Lines starting
  2. with '#' will be ignored, and an empty message aborts the commit.
  3. On branch master
  4. Changes to be committed:
  5. (use “git reset HEAD <file>…” to unstage)
  6. modified: lib/test.rb

~ ~ ”.git/COMMIT_EDITMSG“ 14L, 297C If your team has a commit-message policy, then putting a template for that policy on your system and configuring Git to use it by default can help increase the chance of that policy being followed regularly.

core.pager This setting determines which pager is used when Git pages output such as log and diff. You can set it to more or to your favorite pager (by default, it’s less), or you can turn it off by setting it to a blank string:

$ git config –global core.pager If you run that, Git will page the entire output of all commands, no matter how long they are.

user.signingkey If you’re making signed annotated tags (as discussed in Signing Your Work), setting your GPG signing key as a configuration setting makes things easier. Set your key ID like so:

$ git config –global user.signingkey <gpg-key-id> Now, you can sign tags without having to specify your key every time with the git tag command:

$ git tag -s <tag-name> core.excludesfile You can put patterns in your project’s .gitignore file to have Git not see them as untracked files or try to stage them when you run git add on them, as discussed in Ignoring Files.

But sometimes you want to ignore certain files for all repositories that you work with. If your computer is running macOS, you’re probably familiar with .DS_Store files. If your preferred editor is Emacs or Vim, you know about filenames that end with a ~ or .swp.

This setting lets you write a kind of global .gitignore file. If you create a ~/.gitignore_global file with these contents:

  • ~

.*.swp .DS_Store …and you run git config –global core.excludesfile ~/.gitignore_global, Git will never again bother you about those files.

help.autocorrect If you mistype a command, it shows you something like this:

$ git chekcout master git: 'chekcout' is not a git command. See 'git –help'.

The most similar command is

   checkout
Git helpfully tries to figure out what you meant, but it still refuses to do it. If you set help.autocorrect to 1, Git will actually run this command for you:

$ git chekcout master WARNING: You called a Git command named 'chekcout', which does not exist. Continuing under the assumption that you meant 'checkout' in 0.1 seconds automatically… Note that “0.1 seconds” business. help.autocorrect is actually an integer which represents tenths of a second. So if you set it to 50, Git will give you 5 seconds to change your mind before executing the autocorrected command.

Colors in Git Git fully supports colored terminal output, which greatly aids in visually parsing command output quickly and easily. A number of options can help you set the coloring to your preference.

color.ui Git automatically colors most of its output, but there’s a master switch if you don’t like this behavior. To turn off all Git’s colored terminal output, do this:

$ git config –global color.ui false The default setting is auto, which colors output when it’s going straight to a terminal, but omits the color-control codes when the output is redirected to a pipe or a file.

You can also set it to always to ignore the difference between terminals and pipes. You’ll rarely want this; in most scenarios, if you want color codes in your redirected output, you can instead pass a –color flag to the Git command to force it to use color codes. The default setting is almost always what you’ll want.

color.* If you want to be more specific about which commands are colored and how, Git provides verb-specific coloring settings. Each of these can be set to true, false, or always:

color.branch color.diff color.interactive color.status In addition, each of these has subsettings you can use to set specific colors for parts of the output, if you want to override each color. For example, to set the meta information in your diff output to blue foreground, black background, and bold text, you can run:

$ git config –global color.diff.meta “blue black bold” You can set the color to any of the following values: normal, black, red, green, yellow, blue, magenta, cyan, or white. If you want an attribute like bold in the previous example, you can choose from bold, dim, ul (underline), blink, and reverse (swap foreground and background).

External Merge and Diff Tools Although Git has an internal implementation of diff, which is what we’ve been showing in this book, you can set up an external tool instead. You can also set up a graphical merge-conflict-resolution tool instead of having to resolve conflicts manually. We’ll demonstrate setting up the Perforce Visual Merge Tool (P4Merge) to do your diffs and merge resolutions, because it’s a nice graphical tool and it’s free.

If you want to try this out, P4Merge works on all major platforms, so you should be able to do so. We’ll use path names in the examples that work on macOS and Linux systems; for Windows, you’ll have to change /usr/local/bin to an executable path in your environment.

To begin, download P4Merge from Perforce. Next, you’ll set up external wrapper scripts to run your commands. We’ll use the macOS path for the executable; in other systems, it will be where your p4merge binary is installed. Set up a merge wrapper script named extMerge that calls your binary with all the arguments provided:

$ cat /usr/local/bin/extMerge

  1. !/bin/sh

/Applications/p4merge.app/Contents/MacOS/p4merge $* The diff wrapper checks to make sure seven arguments are provided and passes two of them to your merge script. By default, Git passes the following arguments to the diff program:

path old-file old-hex old-mode new-file new-hex new-mode Because you only want the old-file and new-file arguments, you use the wrapper script to pass the ones you need.

$ cat /usr/local/bin/extDiff

  1. !/bin/sh

[ $# -eq 7 ] && /usr/local/bin/extMerge “$2” “$5” You also need to make sure these tools are executable:

$ sudo chmod +x /usr/local/bin/extMerge $ sudo chmod +x /usr/local/bin/extDiff Now you can set up your config file to use your custom merge resolution and diff tools. This takes a number of custom settings: merge.tool to tell Git what strategy to use, mergetool.<tool>.cmd to specify how to run the command, mergetool.<tool>.trustExitCode to tell Git if the exit code of that program indicates a successful merge resolution or not, and diff.external to tell Git what command to run for diffs. So, you can either run four config commands:

$ git config –global merge.tool extMerge $ git config –global mergetool.extMerge.cmd \

 'extMerge "$BASE" "$LOCAL" "$REMOTE" "$MERGED"'
$ git config –global mergetool.extMerge.trustExitCode false $ git config –global diff.external extDiff or you can edit your ~/.gitconfig file to add these lines:

[merge]

 tool = extMerge
[mergetool “extMerge”]
 cmd = extMerge "$BASE" "$LOCAL" "$REMOTE" "$MERGED"
 trustExitCode = false
[diff]
 external = extDiff
After all this is set, if you run diff commands such as this:

$ git diff 32d1776b1^ 32d1776b1 Instead of getting the diff output on the command line, Git fires up P4Merge, which looks something like this:

P4Merge Figure 142. P4Merge If you try to merge two branches and subsequently have merge conflicts, you can run the command git mergetool; it starts P4Merge to let you resolve the conflicts through that GUI tool.

The nice thing about this wrapper setup is that you can change your diff and merge tools easily. For example, to change your extDiff and extMerge tools to run the KDiff3 tool instead, all you have to do is edit your extMerge file:

$ cat /usr/local/bin/extMerge

  1. !/bin/sh

/Applications/kdiff3.app/Contents/MacOS/kdiff3 $* Now, Git will use the KDiff3 tool for diff viewing and merge conflict resolution.

Git comes preset to use a number of other merge-resolution tools without your having to set up the cmd configuration. To see a list of the tools it supports, try this:

$ git mergetool –tool-help 'git mergetool –tool=<tool>' may be set to one of the following:

       emerge
       gvimdiff
       gvimdiff2
       opendiff
       p4merge
       vimdiff
       vimdiff2

The following tools are valid, but not currently available:

       araxis
       bc3
       codecompare
       deltawalker
       diffmerge
       diffuse
       ecmerge
       kdiff3
       meld
       tkdiff
       tortoisemerge
       xxdiff

Some of the tools listed above only work in a windowed environment. If run in a terminal-only session, they will fail. If you’re not interested in using KDiff3 for diff but rather want to use it just for merge resolution, and the kdiff3 command is in your path, then you can run:

$ git config –global merge.tool kdiff3 If you run this instead of setting up the extMerge and extDiff files, Git will use KDiff3 for merge resolution and the normal Git diff tool for diffs.

Formatting and Whitespace Formatting and whitespace issues are some of the more frustrating and subtle problems that many developers encounter when collaborating, especially cross-platform. It’s very easy for patches or other collaborated work to introduce subtle whitespace changes because editors silently introduce them, and if your files ever touch a Windows system, their line endings might be replaced. Git has a few configuration options to help with these issues.

core.autocrlf If you’re programming on Windows and working with people who are not (or vice-versa), you’ll probably run into line-ending issues at some point. This is because Windows uses both a carriage-return character and a linefeed character for newlines in its files, whereas macOS and Linux systems use only the linefeed character. This is a subtle but incredibly annoying fact of cross-platform work; many editors on Windows silently replace existing LF-style line endings with CRLF, or insert both line-ending characters when the user hits the enter key.

Git can handle this by auto-converting CRLF line endings into LF when you add a file to the index, and vice versa when it checks out code onto your filesystem. You can turn on this functionality with the core.autocrlf setting. If you’re on a Windows machine, set it to true — this converts LF endings into CRLF when you check out code:

$ git config –global core.autocrlf true If you’re on a Linux or macOS system that uses LF line endings, then you don’t want Git to automatically convert them when you check out files; however, if a file with CRLF endings accidentally gets introduced, then you may want Git to fix it. You can tell Git to convert CRLF to LF on commit but not the other way around by setting core.autocrlf to input:

$ git config –global core.autocrlf input This setup should leave you with CRLF endings in Windows checkouts, but LF endings on macOS and Linux systems and in the repository.

If you’re a Windows programmer doing a Windows-only project, then you can turn off this functionality, recording the carriage returns in the repository by setting the config value to false:

$ git config –global core.autocrlf false core.whitespace Git comes preset to detect and fix some whitespace issues. It can look for six primary whitespace issues — three are enabled by default and can be turned off, and three are disabled by default but can be activated.

The three that are turned on by default are blank-at-eol, which looks for spaces at the end of a line; blank-at-eof, which notices blank lines at the end of a file; and space-before-tab, which looks for spaces before tabs at the beginning of a line.

The three that are disabled by default but can be turned on are indent-with-non-tab, which looks for lines that begin with spaces instead of tabs (and is controlled by the tabwidth option); tab-in-indent, which watches for tabs in the indentation portion of a line; and cr-at-eol, which tells Git that carriage returns at the end of lines are OK.

You can tell Git which of these you want enabled by setting core.whitespace to the values you want on or off, separated by commas. You can disable an option by prepending a - in front of its name, or use the default value by leaving it out of the setting string entirely. For example, if you want all but space-before-tab to be set, you can do this (with trailing-space being a short-hand to cover both blank-at-eol and blank-at-eof):

$ git config –global core.whitespace \

   trailing-space,-space-before-tab,indent-with-non-tab,tab-in-indent,cr-at-eol
Or you can specify the customizing part only:

$ git config –global core.whitespace \

   -space-before-tab,indent-with-non-tab,tab-in-indent,cr-at-eol
Git will detect these issues when you run a git diff command and try to color them so you can possibly fix them before you commit. It will also use these values to help you when you apply patches with git apply. When you’re applying patches, you can ask Git to warn you if it’s applying patches with the specified whitespace issues:

$ git apply –whitespace=warn <patch> Or you can have Git try to automatically fix the issue before applying the patch:

$ git apply –whitespace=fix <patch> These options apply to the git rebase command as well. If you’ve committed whitespace issues but haven’t yet pushed upstream, you can run git rebase –whitespace=fix to have Git automatically fix whitespace issues as it’s rewriting the patches.

Server Configuration Not nearly as many configuration options are available for the server side of Git, but there are a few interesting ones you may want to take note of.

receive.fsckObjects Git is capable of making sure every object received during a push still matches its SHA-1 checksum and points to valid objects. However, it doesn’t do this by default; it’s a fairly expensive operation, and might slow down the operation, especially on large repositories or pushes. If you want Git to check object consistency on every push, you can force it to do so by setting receive.fsckObjects to true:

$ git config –system receive.fsckObjects true Now, Git will check the integrity of your repository before each push is accepted to make sure faulty (or malicious) clients aren’t introducing corrupt data.

receive.denyNonFastForwards If you rebase commits that you’ve already pushed and then try to push again, or otherwise try to push a commit to a remote branch that doesn’t contain the commit that the remote branch currently points to, you’ll be denied. This is generally good policy; but in the case of the rebase, you may determine that you know what you’re doing and can force-update the remote branch with a -f flag to your push command.

To tell Git to refuse force-pushes, set receive.denyNonFastForwards:

$ git config –system receive.denyNonFastForwards true The other way you can do this is via server-side receive hooks, which we’ll cover in a bit. That approach lets you do more complex things like deny non-fast-forwards to a certain subset of users.

receive.denyDeletes One of the workarounds to the denyNonFastForwards policy is for the user to delete the branch and then push it back up with the new reference. To avoid this, set receive.denyDeletes to true:

$ git config –system receive.denyDeletes true This denies any deletion of branches or tags — no user can do it. To remove remote branches, you must remove the ref files from the server manually. There are also more interesting ways to do this on a per-user basis via ACLs, as you’ll learn in An Example Git-Enforced Policy.”

Fair Use Sources

Git: Git Fundamentals, Git Inventor - Git Designer: Linus Torvalds, git commands, Git Username, git commit Email Address, Authenticating with GitHub from Git, GitHub, Version control, GitOps, Awesome Git. (navbar_git - see also navbar_github)


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git_configuration.txt · Last modified: 2022/11/16 02:20 by 127.0.0.1