What is gitattributes

The existing binary files will be checked into Git and not LFS without rewriting Git history which would be bad and you shouldn't do unless you are the only developer. You will have to add a one off commit to take the latest versions of all binary files and add them to LFS. Everyone who uses the repository will also have to re-clone the repository I found this out the hard way in a team of 15 people.

Many apologies were made over the course of a week. Ideally you add this from day one and educate developers about Git's treatment of binary files, so people don't check-in any binary files not controlled by LFS.

If your repository is public and you have any traffic going to your site whatsoever, you will get through that very quickly. I really don't understand why GitHub charges for Git LFS because people who don't want to pay are just going to check in binary files in Git instead which presumably would cost them more bandwidth.

Surely they should be encouraging it's use by making it free? When talking about the. As you saw above, we already do this with Git LFS but if you don't use LFS, read on as you may need to explicitly list binary files in certain rare circumstances.

I was interested so I asked a Stack Overflow question and got great answers. If you look at the Git source code , it checks first 8, bytes of a file to see if it contains a NUL character. If it does, the file is assumed to be binary. Added Matlab diff. ENH: Add export-ignore to compiled python files. Jun 10, Update R. May 1, Add script to check for missing. Oct 10, Ruby diff. Apr 19, Create Rust. Oct 8, Jul 6, Added Vim Fix misspelling. Jun 16, Add embedded ruby template.

Nov 4, Jun 13, Distributed Git 5. GitHub 6. Git Tools 7. Customizing Git 8. Git and Other Systems 9. Git Internals Appendix C: Git Commands A3. Binary Files 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. 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. We will begin at the beginning by explaining some background on version control tools, then 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 to , a 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. A filter attribute can be set to a string value that names a filter driver specified in the configuration. A filter driver consists of a clean command and a smudge command, either of which can be left unspecified.

Upon checkout, when the smudge command is specified, the command is fed the blob object from its standard input, and its standard output is used to update the worktree file. Similarly, the clean command is used to convert the contents of worktree file upon checkin. By default these commands process only a single blob and terminate. If a long running process filter is configured then it always takes precedence over a configured single blob filter. See section below for the description of the protocol used to communicate with a process filter.

One use of the content filtering is to massage the content into a shape that is more convenient for the platform, filesystem, and the user to use. For this mode of operation, the key phrase here is "more convenient" and not "turning something unusable into usable". In other words, the intent is that if someone unsets the filter driver definition, or does not have the appropriate filter program, the project should still be usable.

Another use of the content filtering is to store the content that cannot be directly used in the repository e. These two filters behave differently, and by default, a filter is taken as the former, massaging the contents into more convenient shape. A missing filter driver definition in the config, or a filter driver that exits with a non-zero status, is not an error but makes the filter a no-op passthru. You can declare that a filter turns a content that by itself is unusable into a usable content by setting the filter.

Then you would define a "filter. See the section on merging below. The "indent" filter is well-behaved in this regard: it will not modify input that is already correctly indented. In this case, the lack of a smudge filter means that the clean filter must accept its own output without modifying it. If a filter must succeed in order to make the stored contents usable, you can declare that the filter is required , in the configuration:.

A filter might use this in keyword substitution. For example:. Depending on the version that is being filtered, the corresponding file on disk may not exist, or may have different contents. So, smudge and clean commands should not try to access the file on disk, but only act as filters on the content provided to them on standard input. If the filter command a string value is defined via filter. When Git encounters the first file that needs to be cleaned or smudged, it starts the filter and performs the handshake.

In the handshake, the welcome message sent by Git is "git-filter-client", only version 2 is supported, and the supported capabilities are "clean", "smudge", and "delay". The list will contain at least the filter command based on the supported capabilities and the pathname of the file to filter relative to the repository root. Right after the flush packet Git sends the content split in zero or more pkt-line packets and a flush packet to terminate content.

Please note, that the filter must not send any response before it received the content and the final flush packet. If the filter does not experience problems then the list must contain a "success" status.

Right after these packets the filter is expected to send the content in zero or more pkt-line packets and a flush packet at the end. The filter can change the status in the second list or keep the status as is with an empty list.

Please note that the empty list must be terminated with a flush packet regardless. If the result content is empty then the filter is expected to respond with a "success" status and a flush packet to signal the empty content. In case the filter cannot or does not want to process the content, it is expected to respond with an "error" status. If the filter experiences an error during processing, then it can send the status "error" after the content was partially or completely sent.

In case the filter cannot or does not want to process the content as well as any future content for the lifetime of the Git process, then it is expected to respond with an "abort" status at any point in the protocol. However, Git sets its exit code according to the filter. If the filter dies during the communication or does not adhere to the protocol then Git will stop the filter process and restart it with the next file that needs to be processed.

Depending on the filter. If the filter supports the "delay" capability, then Git can send the flag "can-delay" after the filter command and pathname. This flag denotes that the filter can delay filtering the current blob e.

If Git sends this command, then the filter is expected to return a list of pathnames representing blobs that have been delayed earlier and are now available. The list must be terminated with a flush packet followed by a "success" status that is also terminated with a flush packet. If no blobs for the delayed paths are available, yet, then the filter is expected to block the response until at least one blob becomes available.

The filter can tell Git that it has no more delayed blobs by sending an empty list. As soon as the filter responds with an empty list, Git stops asking. All blobs that Git has not received at this point are considered missing and will result in an error. After Git received the pathnames, it will request the corresponding blobs again.

These requests contain a pathname and an empty content section. The filter is expected to respond with the smudged content in the usual way as explained above. Please note that you cannot use an existing filter. In the check-in codepath, the worktree file is first converted with filter driver if specified and corresponding driver defined , then the result is processed with ident if specified , and then finally with text again, if specified and applicable.

In the check-out codepath, the blob content is first converted with text , and then ident and fed to filter. To prevent these unnecessary merge conflicts, Git can be told to run a virtual check-out and check-in of all three stages of a file when resolving a three-way merge by setting the merge. This prevents changes caused by check-in conversion from causing spurious merge conflicts when a converted file is merged with an unconverted file. Filters that do not act in this way may cause additional merge conflicts that must be resolved manually.

The attribute diff affects how Git generates diffs for particular files. It can tell Git whether to generate a textual patch for the path or to treat the path as a binary file.

A path to which the diff attribute is set is treated as text, even when they contain byte values that normally never appear in text files, such as NUL. A path to which the diff attribute is unset will generate Binary files differ or a binary patch, if binary patches are enabled.

A path to which the diff attribute is unspecified first gets its contents inspected, and if it looks like text and is smaller than core. Otherwise it would generate Binary files differ. Diff is shown using the specified diff driver. Each driver may specify one or more options, as described in the following section.

The options for the diff driver "foo" are defined by the configuration variables in the "diff. The definition of a diff driver is done in gitconfig , not gitattributes file, so strictly speaking this manual page is a wrong place to talk about it. When Git needs to show you a diff for the path with diff attribute set to jcdiff , it calls the command you specified with the above configuration, i.

See git[1] for details. Each group of changes called a "hunk" in the textual diff output is prefixed with a line of the form:.