git apply: Usage, Options & Common CI Errors

git apply takes a diff/patch file and applies its changes - without creating commits.

apply is how you replay a diff in CI (e.g. a generated patch). Use --check first and --3way for resilience.

What it does

git apply reads a unified diff and modifies files in the working tree (and, with --index, the index) to match it. Unlike git am it does not create commits.

Common usage

Terminal

git apply changes.patch
git apply --check changes.patch    # dry run, validate only
git apply --3way changes.patch     # fall back to 3-way merge
git apply --index changes.patch    # also stage the result
git diff > out.patch && git apply out.patch

Options

Flag	What it does
--check	Validate without applying
--3way / -3	Use 3-way merge on conflict
--index	Apply to the index as well
-p<n>	Strip n leading path components
-R / --reverse	Apply the patch in reverse

Common errors in CI

error: patch failed: <file>:<n> / "error: <file>: patch does not apply" - the target file drifted from what the patch expects. Try git apply --3way, fix the path level with -p, or regenerate the patch against the current base.

Related guides

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