# `once cache blob exists`

Check whether a blob exists. Exits 0 on hit, 1 on miss; with `--format json|toon`, always exits 0 and reports `present` in the structured output

## Synopsis

```text
once cache blob exists [OPTIONS] <DIGEST>
```

## Arguments

| Argument | Required | Description |
| --- | --- | --- |
| `<DIGEST>` | yes | Blob digest to probe |

## Options

| Flag | Value | Default | Description |
| --- | --- | --- | --- |
| `-C, --directory` | `<DIR>` |  | Project root. Defaults to the current directory; the cache lives under `<project>/.once/`. Mirrors `make -C` |
| `--format` | `<FORMAT>` | `human` | Output format for Once's structured data (`cache stats`, `run`/`exec` trailers). Defaults to a human-readable rendering; pass `json` or `toon` to get machine-parseable output for scripting and for agent consumers |
| `-v, --verbose` | (flag) | `0` | Increase log verbosity. Repeat for more (-v: info, -vv: debug, -vvv: trace). Overridden by `RUST_LOG` |
| `-q, --quiet` | (flag) | `false` | Suppress human-mode success and progress trailers. Errors and the structured envelope of `--format json`/`toon` still print. Mirrors the `-q` flag of common build tools |
| `--list` | (flag) | `false` | Print the command surface at the current command depth |
| `--memory-limit` | `<SIZE>` |  | Maximum memory scheduling budget for local actions. Defaults to two thirds of the memory visible to the host or container |