# Quickstart

> Scan your Mac, see what is using the space, clean what is safe and review the rest, in five steps.

## 1. Turn on the command line

Open Disk Census, go to the **CLI and Agents** tab, and turn on the command line. Then open a new Terminal window and check that your shell finds `census`:

```sh
census version
```

If your shell can't find `census`, check that the command line is turned on in the **CLI and Agents** tab, then open a new Terminal window.

## 2. Scan your Mac

Run `census` with no command. It scans the whole startup drive, saves the result, and prints a summary:

```sh
census
```

```text title="Example output"
Macintosh HD   46.7 GB used · 16.1 GB free

  24.2 GB   ███████▎        macOS
   7.3 GB   ██▏             Developer
   5.6 GB   █▋              Applications
   3.2 GB   █               System Data
   2.6 GB   ▊               Hidden space
   2.0 GB   ▋               App data
   1.9 GB   ▌               Everything else

Biggest files
   7.1 GB   /System/Volumes/Preboot/F3022DFD-…/…/os.clone.dmg
   1.2 GB   /System/Library/AssetsV2/…/index.sql
   1.1 GB   /System/Volumes/VM/swapfile0

Safe to clean: 269 MB → census findings
```

The rows add up to the disk's used space. **Hidden space** is used space that no file census could read accounts for: snapshots, the Recovery volume, files macOS protects, and folders census couldn't open. [Scans and scopes](https://diskcensus.com/docs/cli/scans.md#summary) explains every row.

The first scan walks the whole drive. Later scans read again only the folders that changed since the last one.

## 3. See what's using space

Queries read the saved scan instead of walking the disk again:

```sh
# The largest folders, three levels deep
census top

# The ten largest files
census top --files --limit 10

# Files of 1 GB or more you haven't opened in a year
census large --min-size 1G --not-opened 365

# How the space splits into buckets: Applications, Developer, AI agents, …
census breakdown
```

## 4. Clean what's safe

`census clean` rescans, lists the **safe** findings (caches, build output and logs that rebuild themselves), and asks before it deletes them:

```sh
census clean
```

```text title="Example session"
Safe to delete: 31 items · 2.0 GB
    1.2 GB  Developer caches
    0.6 GB  App caches
    0.2 GB  Logs
Delete them? [y/N] y
Freed 2.0 GB · used 46.7 GB → 44.7 GB · skipped 2
14 items need review → census review
```

Items in use, such as the caches of an app that is running, are skipped and saved for review. Deletion is permanent: nothing goes to the Trash.

## 5. Review the rest

Everything that isn't safe waits in a review set until you choose. `census review` shows it as a numbered menu:

```sh
census review
```

```text title="Example session"
Needs review · 14 items · 6.3 GB
  1    3.1 GB  ~/proj/foo/target  Cargo build output
  2    1.4 GB  ~/Downloads/Xcode_15.xip  Installer in Downloads
Delete which? (1,3-5 · Enter for none): 2
Permanently delete 1 item (1.4 GB)? Type delete: delete
Freed 1.4 GB · used 44.7 GB → 43.3 GB
```

Press Return at `Delete which?` to keep everything. Nothing you leave out is touched.

## Next steps

- [Finding what to remove](https://diskcensus.com/docs/cli/find.md): large and old files, duplicates, app leftovers.
- [Safety and deletion](https://diskcensus.com/docs/cli/safety.md): what `census` will and won't delete, and the checks before each deletion.
- [JSON output](https://diskcensus.com/docs/cli/json.md): drive `census` from scripts.
- [Census for AI agents](https://diskcensus.com/docs/agents.md): let your coding agent do this for you, with your approval.