For example, the character that means man in the Lishu system from 200 BC is similar to the character that means man from the Jiantizi, or modern simplified system, of the twentieth century.
例如，公元前200年的隶书系统中的“人”字与20世纪的简体系统中的“人”字相似。
2
You can think of tr as a (very) simplified variant of sed: it will replace one character with another or remove some characters altogether.