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Diffstat (limited to 'Documentation/gitattributes.txt')
| -rw-r--r-- | Documentation/gitattributes.txt | 110 |
1 files changed, 85 insertions, 25 deletions
diff --git a/Documentation/gitattributes.txt b/Documentation/gitattributes.txt index 7e7e121..80120ea 100644 --- a/Documentation/gitattributes.txt +++ b/Documentation/gitattributes.txt @@ -79,7 +79,7 @@ Attributes for all users on a system should be placed in the `$(prefix)/etc/gitattributes` file. Sometimes you would need to override an setting of an attribute -for a path to `unspecified` state. This can be done by listing +for a path to `Unspecified` state. This can be done by listing the name of the attribute prefixed with an exclamation point `!`. @@ -294,16 +294,27 @@ output is used to update the worktree file. Similarly, the `clean` command is used to convert the contents of worktree file upon checkin. -A missing filter driver definition in the config is not an error -but makes the filter a no-op passthru. +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. -The content filtering is done to massage the content into a -shape that is more convenient for the platform, filesystem, and -the user to use. 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.g. a UUID that refers to the true +content stored outside git, or an encrypted content) and turn it into a +usable form upon checkout (e.g. download the external content, or decrypt +the encrypted content). + +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.<driver>.required configuration +variable to `true`. For example, in .gitattributes, you would assign the `filter` attribute for paths. @@ -335,6 +346,16 @@ 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: + +------------------------ +[filter "crypt"] + clean = openssl enc ... + smudge = openssl enc -d ... + required +------------------------ + Sequence "%f" on the filter command line is replaced with the name of the file the filter is working on. A filter might use this in keyword substitution. For example: @@ -500,6 +521,8 @@ patterns are available: - `java` suitable for source code in the Java language. +- `matlab` suitable for source code in the MATLAB language. + - `objc` suitable for source code in the Objective-C language. - `pascal` suitable for source code in the Pascal/Delphi language. @@ -593,6 +616,37 @@ and now produces better output), you can remove the cache manually with `git update-ref -d refs/notes/textconv/jpg` (where "jpg" is the name of the diff driver, as in the example above). +Choosing textconv versus external diff +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +If you want to show differences between binary or specially-formatted +blobs in your repository, you can choose to use either an external diff +command, or to use textconv to convert them to a diff-able text format. +Which method you choose depends on your exact situation. + +The advantage of using an external diff command is flexibility. You are +not bound to find line-oriented changes, nor is it necessary for the +output to resemble unified diff. You are free to locate and report +changes in the most appropriate way for your data format. + +A textconv, by comparison, is much more limiting. You provide a +transformation of the data into a line-oriented text format, and git +uses its regular diff tools to generate the output. There are several +advantages to choosing this method: + +1. Ease of use. It is often much simpler to write a binary to text + transformation than it is to perform your own diff. In many cases, + existing programs can be used as textconv filters (e.g., exif, + odt2txt). + +2. Git diff features. By performing only the transformation step + yourself, you can still utilize many of git's diff features, + including colorization, word-diff, and combined diffs for merges. + +3. Caching. Textconv caching can speed up repeated diffs, such as those + you might trigger by running `git log -p`. + + Marking files as binary ^^^^^^^^^^^^^^^^^^^^^^^ @@ -632,7 +686,7 @@ Performing a three-way merge `merge` ^^^^^^^ -The attribute `merge` affects how three versions of a file is +The attribute `merge` affects how three versions of a file are merged when a file-level merge is necessary during `git merge`, and other commands such as `git revert` and `git cherry-pick`. @@ -646,15 +700,15 @@ Unset:: Take the version from the current branch as the tentative merge result, and declare that the merge has - conflicts. This is suitable for binary files that does + conflicts. This is suitable for binary files that do not have a well-defined merge semantics. Unspecified:: By default, this uses the same built-in 3-way merge - driver as is the case the `merge` attribute is set. - However, `merge.default` configuration variable can name - different merge driver to be used for paths to which the + driver as is the case when the `merge` attribute is set. + However, the `merge.default` configuration variable can name + different merge driver to be used with paths for which the `merge` attribute is unspecified. String:: @@ -837,7 +891,7 @@ If this attribute is not set or has an invalid value, the value of the (See linkgit:git-config[1]). -USING ATTRIBUTE MACROS +USING MACRO ATTRIBUTES ---------------------- You do not want any end-of-line conversions applied to, nor textual diffs @@ -848,24 +902,27 @@ produced for, any binary file you track. You would need to specify e.g. ------------ but that may become cumbersome, when you have many attributes. Using -attribute macros, you can specify groups of attributes set or unset at -the same time. The system knows a built-in attribute macro, `binary`: +macro attributes, you can define an attribute that, when set, also +sets or unsets a number of other attributes at the same time. The +system knows a built-in macro attribute, `binary`: ------------ *.jpg binary ------------ -which is equivalent to the above. Note that the attribute macros can only -be "Set" (see the above example that sets "binary" macro as if it were an -ordinary attribute --- setting it in turn unsets "text" and "diff"). +Setting the "binary" attribute also unsets the "text" and "diff" +attributes as above. Note that macro attributes can only be "Set", +though setting one might have the effect of setting or unsetting other +attributes or even returning other attributes to the "Unspecified" +state. -DEFINING ATTRIBUTE MACROS +DEFINING MACRO ATTRIBUTES ------------------------- -Custom attribute macros can be defined only in the `.gitattributes` file -at the toplevel (i.e. not in any subdirectory). The built-in attribute -macro "binary" is equivalent to: +Custom macro attributes can be defined only in the `.gitattributes` +file at the toplevel (i.e. not in any subdirectory). The built-in +macro attribute "binary" is equivalent to: ------------ [attr]binary -diff -text @@ -921,6 +978,9 @@ frotz unspecified ---------------------------------------------------------------- +SEE ALSO +-------- +linkgit:git-check-attr[1]. GIT --- |