Show progress during dd copy_show progress on dd-优快云博客

本文介绍如何在Linux环境下使用dd命令复制文件，并通过发送特殊信号获取复制过程的进度报告。dd命令通常用于复制整个磁盘映像，其静默操作模式非常适合于脚本环境。文中提供了一个示例，演示如何复制指定大小的数据块，以及在dd运行过程中通过发送USR1信号获取实际进度。

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dd is a popular, generic command-line tool for copying files from 1 location to another. It is often used to copy entire disk images.

Like many Linux command line tools, it operates silently unless something unexpected happens. Its lack of visual progress feedback is a nice feature for scripting. However, it can leave you wondering about its progress if you are interactively dd-copying a large disk.

To illustrate, you run the following (valid, but perhaps not very useful) dd copy:

$ dd if=/dev/random of=/dev/null bs=1K count=100

It will run for a few minutes as it copies (and immediately discards) 100 blocks of randomly generated data, each of size 1 KB.

To get a progress report while dd is running, you need to open another virtual terminal, and then send a special USR1 signal to the dd process.

First, find out the process id of the dd process by running the following in the new virtual terminal.