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Plumbing vs Porcelain

Plumbing Versus Porcelain Commands

Plumbing commands (hash-object, cat-file, write-tree, commit-tree, update-ref, rev-parse) do one low-level job with stable output; Git 1,932 's first commit contained little else. Porcelain commands (add, commit, log, status, switch) are the friendly layer on top, and their output may change between releases:

Porcelain commands and the plumbing beneath them
Porcelain Plumbing equivalent
git add file hash-object -w, then update-index --add
git commit write-tree, commit-tree, then update-ref HEAD
git switch branch read-tree, checkout-index, symbolic-ref HEAD
git branch name update-ref refs/heads/name HEAD

Scripts should use plumbing, or porcelain with a stable format such as the confusingly named --porcelain:

Machine-readable status for scriptsShell
echo 'draft' > notes.txt; echo 'x' >> README.md
git status --porcelain --branch
Output
## main
 M README.md
?? notes.txt

It uses the two-column codes of status --short, and --porcelain=v2 adds modes and hashes. Parse these, never the human output, which is translated and reworded between releases.