---
name: fastcp
version: 1.1.1
description: "Multi-target parallel file copy CLI. Reads source once into memory, writes to multiple USB drives concurrently. | 多目标并行复制工具，源文件只读一次，同时写入多个U盘。"
user_invocable: true
---

# FastCP - 多目标并行复制 / Multi-target Parallel Copy

将源目录一次性读入内存，并行复制到多个目标（U盘）。专为 AI 工具自动化调用设计：
非终端环境自动进入安静模式，`--json` 输出机器可读结果。

Read source directory into memory once, copy to multiple targets (USB drives) in parallel.
Designed for AI tool automation: auto-quiet in non-TTY environments, machine-readable `--json` output.

## 使用场景 / When to use
- 同一份文件同时复制到多个U盘 / Copy same files to multiple USB drives
- 批量部署文件到多个目标目录 / Batch deploy to multiple destinations
- 需要复制后校验完整性 / Copy with integrity verification
- AI/脚本调用需要结构化结果 / AI or scripts need structured output

## 安装 / Install

```bash
go install github.com/dongsheng123132/fastcp@latest
```

或从 GitHub Releases 下载二进制。/ Or grab a binary from GitHub Releases.

## 用法 / Usage

```bash
# 复制到多个U盘 / Copy to multiple USB drives
fastcp <source_dir> <target1> <target2> [target3] ...

# Windows 示例
fastcp.exe D:\源文件夹 E:\ F:\ G:\ H:\

# Linux/macOS 示例
fastcp /path/to/source /media/usb1 /media/usb2 /media/usb3

# 带校验 / With verification (xxhash)
fastcp --verify <source> <target1> <target2>

# AI/脚本调用：JSON 输出 / For AI/scripts: JSON output
fastcp --json --verify <source> <target1> <target2>

# 增量复制 / Incremental (skip unchanged)
fastcp --incremental <source> <target1>

# 控制并发数 / Control parallelism (default 3)
fastcp -c 2 <source> <target1> <target2> <target3>

# 预览模式 / Preview without copying
fastcp --dry-run <source> <target1> <target2>
```

## 参数 / Flags

- `-c, --concurrency N`: 同时写入目标数 / simultaneous target writes (default 3)
- `-b, --buffer-size`: 写缓冲区 / write buffer (default 4M)
- `--verify`: xxhash 校验 / integrity check after copy
- `--incremental`: 跳过未变更文件 / skip unchanged files
- `--dry-run`: 预览不复制 / preview only
- `--preload-all`: 强制全量预加载 / force all files into memory
- `--json`: JSON 输出（AI/脚本用）/ JSON output (for AI/scripts)
- `-q, --quiet`: 极简输出 / minimal output
- `-v, --verbose`: 详细输出 / verbose output

TTY 行为：终端默认人类可读输出；非终端（管道/AI 调用）自动安静。
TTY behavior: human-readable output in terminals; auto-quiet when piped or driven by AI tools.

## 典型流程 / Typical workflow
1. 确认U盘挂载盘符 / Identify mounted drives
2. 执行: `fastcp --verify D:\source E:\ F:\ G:\`
3. 检查校验结果 / Check verification output

## JSON 契约 / JSON contract

`--json` 输出顶层 `ok`（bool）、`targets`（数组）、`elapsed`；字段 snake_case。

```json
{ "ok": true, "targets": [ { "path": "E:\\", "ok": true, "files": 12, "bytes": 1234567 } ], "elapsed": "25ms" }
```