# git bisect run: Usage, Options & Common CI Errors

> git bisect run automates a bisect with a test script’s exit code. Reference for the good/bad/skip exit codes (0, 1-127, 125) and automating regressions in CI.

Source: https://latchkey.dev/learn/command-reference/git-bisect-run  
Updated: 2026-06-25

git bisect run drives the whole binary search automatically using a test script.

Once a test cleanly distinguishes good from bad, bisect run finds the first bad commit with zero manual marking - ideal for catching regressions in CI without a human in the loop.

## What it does

git bisect run executes a command at each bisection step and uses its exit code to mark the commit good, bad, or skip, halving the range automatically until it isolates the first bad commit.

## Common usage

```Terminal
git bisect start HEAD v1.0.0    # bad=HEAD, good=v1.0.0
git bisect run ./test.sh
git bisect run make check
git bisect reset                # always clean up afterward
```

## Options

| Exit code | Meaning to bisect |
| --- | --- |
| 0 | Commit is good |
| 1–124, 126, 127 | Commit is bad |
| 125 | Skip: commit cannot be tested |
| ≥128 | Abort the bisect session |

## Common errors in CI

A script that returns 125 unintentionally (e.g. "command not found" is 127, but a wrapper may emit 125) corrupts the search by skipping testable commits. Make the script return 0/1 deliberately and reserve 125 for genuinely untestable builds. Always end with git bisect reset, and ensure full history (no shallow clone).

## Using this in CI

CI checkouts are shallow and detached by default, which changes the answer this command gives you. Commands that read history, branch names, or tags need the checkout configured for it.

```.github/workflows/ci.yml
- uses: actions/checkout@v4
  with:
    fetch-depth: 0   # history, tags, and git describe all need this

- run: |
    git rev-parse --is-shallow-repository   # expect false
    git rev-parse --abbrev-ref HEAD          # prints HEAD when detached
```

> `git rev-parse --abbrev-ref HEAD` returns the literal string `HEAD` on a detached checkout rather than a branch name. On GitHub Actions read `github.ref_name` instead; the git command cannot know what it was checked out for.

## FAQ

### git bisect run: Usage, Options & Common CI Errors?

Once a test cleanly distinguishes good from bad, bisect run finds the first bad commit with zero manual marking - ideal for catching regressions in CI without a human in the loop.

### What it does?

git bisect run executes a command at each bisection step and uses its exit code to mark the commit good, bad, or skip, halving the range automatically until it isolates the first bad commit.

### Common errors in CI?

A script that returns 125 unintentionally (e.g. "command not found" is 127, but a wrapper may emit 125) corrupts the search by skipping testable commits. Make the script return 0/1 deliberately and reserve 125 for genuinely untestable builds. Always end with git bisect reset, and ensure full history (no shallow clone).

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Latchkey runs CI/CD that repairs its own failures. Agent entry points: https://latchkey.dev/agent.txt, https://latchkey.dev/openapi.json, https://latchkey.dev/llms.txt