Mercurial's primary command is hg, which supports a set of sub-commands that are similar to those in other VCS systems.
Mercurial的主要命令是hg,它支持与其他VCS系统相似的一套子命令。
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When a shell launches a command, such as cp or ls, it spawns a new process for the command, and then waits for the (sub)process to finish before proceeding.