git update-index Command in CI

git update-index is the plumbing command that registers file contents and flags in the index.

Most workflows stage via git add, but CI occasionally needs lower-level control: fixing a file mode, or telling Git to stop noticing changes to a file. update-index provides it.

Common flags

• --chmod=+x <file> - set the executable bit on a tracked file in the index
• --assume-unchanged <file> - tell Git to skip checking a file for changes
• --no-assume-unchanged <file> - undo assume-unchanged
• --skip-worktree <file> - ignore local edits to a tracked file
• --refresh - refresh the stat information in the index to match the working tree
• --add / --remove - explicitly add or remove a path

Example

# Make a committed script executable on a case-insensitive runner
git update-index --chmod=+x scripts/deploy.sh
git commit -m "Mark deploy.sh executable"

In CI

git update-index --chmod=+x reliably sets the executable bit even on filesystems that do not preserve permissions, fixing "permission denied" on committed scripts. Use --refresh to clear false "modified" stat differences after a checkout on some runners.

Key takeaways

• git update-index --chmod=+x fixes executable bits lost on permission-blind filesystems.
• --refresh clears spurious modified flags caused by stat differences after checkout.
• assume-unchanged and skip-worktree are local-only hints, not a way to ignore committed files.

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