“env"和“env"有什么区别?和“设置"(在 Mac OS X 或 Linux 上)? [英] What's the difference between "env" and "set" (on Mac OS X or Linux)?

问题描述

我在运行env"和set"时得到了类似的结果.Set 提供更多结果 - 它是 env 的超集吗?

I get similar results running "env" and "set". Set gives more results - is it a superset of env?

set 的手册页没有提供任何信息.这些命令是如何工作的，有什么区别?

The man page for set doesn't give any information. How do these commands work and what's the difference?

推荐答案

长话短说:set 可以看到 shell-local 变量，env 不能.

Long story short: set can see shell-local variables, env cannot.

Shell 可以有 2 种类型的变量:本地变量，只能从当前 shell 访问，以及(导出的)环境变量，传递给每个执行的程序.

Shells can have variables of 2 types: locals, which are only accessible from the current shell, and (exported) environment variables, which are passed on to every executed program.

由于set 是一个内置 shell 命令，它还可以查看shell 局部变量(包括shell 函数).另一方面，env 是一个独立的可执行文件；它只看到 shell 传递给它的变量或环境变量.

Since set is a built-in shell command, it also sees shell-local variables (including shell functions). env on the other hand is an independent executable; it only sees the variables that the shell passes to it, or environment variables.

当您键入像 a=1 这样的行时，会创建一个局部变量(除非它已经存在于环境中).使用 export a=1

When you type a line like a=1 then a local variable is created (unless it already existed in the environment). Environment variables are created with export a=1

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