> For the complete documentation index, see [llms.txt](https://book.bsdcn.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://book.bsdcn.org/man/man1/truss.1.md).

# truss.1

`truss` — 跟踪系统调用

## 名称

`truss`

## 概要

`truss [-facedDHS] [-o file] [-s strsize] -p pid`

`truss [-facedDHS] [-o file] [-s strsize] command [args]`

## 描述

`truss` 实用程序跟踪指定进程或程序所调用的系统调用。输出到指定输出文件，默认为标准错误。它通过 ptrace(2) 停止并重启被监视的进程来实现此功能。

选项如下：

**`-f`** 跟踪由 fork(2)、vfork(2) 等创建的原始被跟踪进程的后代。为区分进程间的事件，每次事件的输出中包含进程的进程 ID（PID）。

**`-a`** 显示每次 execve(2) 系统调用中传递的参数字符串。

**`-c`** 不显示单个系统调用或信号。而是在退出前打印摘要，包含每个系统调用的：使用的总系统时间、调用次数以及调用返回错误的次数。

**`-e`** 显示每次 execve(2) 系统调用中传递的环境字符串。

**`-d`** 在输出中包含时间戳，显示自跟踪开始以来流逝的时间。

**`-D`** 在输出中包含时间戳，显示自上次记录事件以来流逝的时间。

**`-H`** 在每次事件的输出中包含线程 ID。

**`-S`** 不显示进程接收到的信号信息。（通常，`truss` 同时显示信号和系统调用事件。）

**`-o`** `file` 将输出打印到指定的 `file` 而非标准错误。

**`-s`** `strsize` 显示字符串时最多使用 `strsize` 个字符。如果缓冲区更大，字符串末尾将显示 "..."。默认 `strsize` 为 32。

**`-p`** `pid` 跟踪由 `pid` 指定的进程，而非新命令。

**`command`** \[`args`] 执行 `command` 并跟踪其系统调用。（`-p` 和 `command` 选项互斥。）

## 实例

跟踪用于回显 "hello" 的系统调用：

```sh
$ truss /bin/echo hello
```

与上例相同，但将输出写入文件：

```sh
$ truss -o /tmp/truss.out /bin/echo hello
```

跟踪一个已在运行的进程：

```sh
$ truss -p 34
```

## 参见

[dtrace(1)](https://github.com/FreeBSD-Ask/freebsd-man-sc/blob/main/man1/dtrace.1.md), [kdump(1)](/man/man1/kdump.1.md), [ktrace(1)](/man/man1/ktrace.1.md), ptrace(2), utrace(2), sysdecode(3)

## 历史

`truss` 命令由 Sean Eric Fagan 为 FreeBSD 编写。它仿照 System V Release 4 和 SunOS 上可用的类似命令。


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://book.bsdcn.org/man/man1/truss.1.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.