Git Attributes Decide a File's Line Endings

A generated patch is easier to review when line endings stay predictable. Git diff produces patch text from file changes. If line endings change along with the intended edit, the patch can contain distracting changes. A committed .gitattributes file gives contributors shared rules for the paths it matches. Git’s attributes manual explains how those rules affect files added to the index and checked out into a working tree.

Where Git converts line endings

The text attribute tells Git to store a matching text file with LF line endings in the index. The eol attribute chooses the line endings used when Git checks that file out. Set eol=lf for a file that should have LF in the working tree, even when contributors use different operating systems. Git says eol applies when text or text=auto is set; specifying eol also sets text when it was unspecified. Git’s attributes manual describes both conversions.

A rule for patch files

Put this in the repository’s .gitattributes file:

* text=auto
*.patch text eol=lf
*.diff text eol=lf

The first line asks Git to identify text files and normalize eligible files when they are added. The next lines explicitly treat tracked patch and diff files as text and check them out with LF. The explicit text matters for a known text format: Git documents an exception for files already stored with CRLF under text=auto. Keep binary formats out of any rule that forces text. Git’s examples show both automatic normalization and per-pattern exceptions.

Existing files need a review

Adding attributes does not itself rewrite every tracked file already in the index. Git’s documented migration uses git add --renormalize ., followed by git status to inspect the staged changes. Review that list before committing: it may include files whose stored line endings change. For a tracked patch file, git ls-files --eol -- path/to/change.patch shows line endings in the index and working tree, plus the effective attribute. Git’s migration instructions and the ls-files manual describe these checks.

What to do

1. Add a narrow .gitattributes rule for the text files whose endings must be stable.
2. Inspect a representative tracked file with git ls-files --eol.
3. Renormalize tracked files, review git status, and commit the intended changes.
4. Generate a fresh patch and inspect it for the intended edit.