What does the value means in git?

Question

In a .gitattributes file I found the following line

*.cs   text diff=csharp

what does it mean?

Answer 1

It means that for .cs (CSharp) files, git will use text diff=csharp as the merge/diff mode.

This allows git to have a higher probability of success rates while merging.

Also see the gitattributes doc, which states:

Setting the text attribute on a path enables end-of-line normalization
and marks the path as a text file. End-of-line conversion takes place
without guessing the content type.

and

There are a few built-in patterns to make this easier,
and tex is one of them, so you do not have to write the above
in your configuration file (you still need to enable this with the attribute mechanism,
via .gitattributes). The following built in patterns are available:
[...]
csharp suitable for source code in the C# language.

Answer 2

*.cs 

means all files with .cs as the file extension.

diff

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.

csharp 

suitable for source code in the C# language.

Answer 3

It tells git to use a text merge for all csharp code files.

It also makes the diff information for the commit language specific. This means you can see what method of the code the diff was made in by looking at the header of the commit.