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exec

Runs a shell command. Produces no measurement — use it for build steps that set up repo state for a later measurement step.

exec is the default tool: if a step has a cmd field and no tool field, it runs with exec.

FieldRequiredDescription
cmdyesShell command to run (passed to sh -c).
envnoExtra environment variables merged into the current environment.
cwdnoWorking directory override. Defaults to the project root.
[[steps]]
name = "build"
cmd = "cargo build --release"
env = { CARGO_INCREMENTAL = "1", RUSTFLAGS = "-C opt-level=3" }

Always writes { "measurement": null }. A non-zero exit code marks the step as failed and skips its measurement, but does not abort the rest of the scenario run.