8.2 Customizing Git - Git Attributes
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Some of these settings can also be specified for a path, so that Git applies those settings only for a subdirectory or subset of files. These path-specific empleo agente comercial sevilla are called Git attributes and are set either in a. Using attributes, you using git for binary data do things like specify separate merge strategies for individual files or directories in your project, tell Git how to diff non-text files, or have Git filter content before you check it into or out of Git.
One cool trick for which you can use Git attributes is telling Git which files are binary in cases it otherwise may not be able to figure out and giving Git special instructions about how to handle those files. For instance, some text files may be machine generated and not diffable, whereas some binary files can be diffed.
Some using git for binary data look like text files but for all intents and purposes are to be treated as binary data. For instance, Xcode projects on the Mac contain a file that ends in.
The file is meant to be consumed by a machine. In essence, you want to treat it like a binary file. To tell Git to treat all pbxproj files as binary data, add the following line to your. You can also use the Git attributes functionality to effectively diff binary files. You using git for binary data this by telling Git how to convert your binary data to a text format that can be compared via the normal diff.
Everyone knows that Word is the most horrific editor around, but oddly, everyone still uses it. If you want to version-control Word documents, you can stick them in a Git repository and commit every once in a while; but what good does that do? If you run git diff normally, you only see something like this:.
It turns out you can do this fairly well using Git attributes. Put the following line in your. This tells Git that any file that matches this pattern. You have to set it up. Finally, you can configure Git to use this script:.
Now Git knows that if it tries to do a diff between two snapshots, and any of the files end in. This effectively makes nice text-based versions of your Word files before attempting to diff them. Chapter 1 of this using git for binary data was converted using git for binary data Word format and committed in a Git repository. Then a new paragraph was added. Another interesting problem you can solve this way involves diffing image files.
One way to do this is to run image files through a filter that extracts their EXIF information — metadata that is recorded with most image formats. If you download and install the exiftool program, you can use it to using git for binary data your images into text about the metadata, so at least the diff will show you a textual representation of any changes that happened. If you replace an image in your project and run git diffyou see something like this:.
Git attributes offers you two ways to do this. If you set this attribute on a file or set of files, then the next using git for binary data you check out that branch, Git will replace that field with the SHA-1 of the blob.
However, that result is of limited use. These filters can be set to do all sorts of fun things. The original commit message for this feature gives a simple example of running all your C source code through the indent program before committing. You can set it up by setting the filter attribute in your.
The cat program does essentially nothing: This combination effectively filters all C source code files through indent before committing. To do this properly, you need a small script that takes a filename, figures out the last commit date for this project, and inserts the date into the file. Here is a small Ruby script that does that:. If you commit those changes and check out the file again, you see the keyword properly substituted:. You can see how powerful this technique can be for customized applications.
You have to be careful, though, because the. When you design these filters, they should be able to fail gracefully and have the project still work properly.
Git attribute data also allows you to do some interesting things when exporting an archive of your project. You can tell Git not to export certain files or directories when generating an archive. You can add the following line to your Git attributes file:. When exporting files for deployment you can apply git log 's formatting and keyword-expansion processing to selected portions of files marked with the export-subst attribute.
The substitutions can include for example the commit message and any git notesand git log can do simple word wrapping:. You can also use Git attributes to tell Git to use using git for binary data merge strategies for specific files in your project. This is helpful if a branch in your project has diverged or is specialized, but you using git for binary data to be able to merge changes back in from it, and you want to ignore certain files.
Say you have a database settings file called database. You can set up an attribute like this:. If you merge in the other branch, instead of having merge conflicts with the database.
Git on the Server 4. Git and Other Systems 9. Git using git for binary data Other Environments A1. Embedding Git in your Applications A2. Binary Files One cool trick for which you can use Git attributes is telling Git which files are binary in cases it using git for binary data may not be able to figure out and giving Using git for binary data special instructions about how to handle those files.
Identifying Binary Files Some files look like text files but for all intents and purposes are to be treated as binary data.
Diffing Binary Files You can also use the Git attributes functionality to effectively diff binary files. If you run git diff normally, you only see something like this: Finally, you can configure Git to use this script: We will begin at the beginning by explaining some background on version control tools, using git for binary data move on to how to get Git running on your system and finally how to get it setup to start working with.
At the end of this chapter you should understand why Git is around, why you should use it and you should be all setup to do so. About Version Control What is "version control", and why should you care? Version control is a system that records changes to a file or set of files over time so that you can recall specific versions later. For the examples in this book you will use software source code as the files being version controlled, though in reality you can do this with nearly any type of file on a computer.
If you are a graphic or web designer and want to keep every version of an image or layout which you would most certainly want toa Version Control System VCS is a very wise thing to use.
It allows you to revert files back to a previous state, revert the entire project back to a previous state, compare changes over time, see who last modified something that might be causing a problem, who introduced an issue and when, and more. Using a VCS also generally means that if you screw things up or lose files, you can easily recover.
In addition, you get all this for very little overhead. Local Version Control Systems Many people's version-control method of choice is to copy files into another directory perhaps a time-stamped directory, if they're clever. This approach is very common because it is so simple, but it is also incredibly error prone.
It is easy to forget which directory you're in and accidentally write to the wrong file or copy over files you don't mean to. If you replace an image in your project and run git diffyou see something like this: You can easily see that the file size and image dimensions have both changed. The next time using git for binary data check out this file, Git injects the SHA-1 of the blob: Here is a small Ruby script that does that: If you commit those changes and check out the file again, you see the keyword properly substituted: Tue Apr 21 Exporting Your Repository Git attribute data also allows you to do some interesting things when exporting an archive using git for binary data your project.
You can add using git for binary data following line to your Git attributes file: When you run git archivethe contents of the archived file will look like this: The substitutions can include for example the commit message and any git notesand git log can do simple word wrapping: Merge Strategies You can also use Git attributes to tell Git to use different merge strategies for specific files in your project. You can set up an attribute like this: In this case, database.