覆盖变量从命令行bash脚本 [英] override variable in bash script from command line

问题描述

如何在命令行您bash脚本覆盖一个变量？我知道如何传递变量，但我只是希望像./myscript.sh -Dvar = VAL

How do you override a variable in your bash script from command line? I know how to pass variables in, but I just want something like ./myscript.sh -Dvar=val

推荐答案

您需要使用参数扩展为变量（S）要覆盖：

You need to use parameter expansion for the variable(s) you want to override:

$ cat override.sh
#!/bin/bash

: ${var1:=foo} # var1 will take on the value "foo" if not overridden
var2=${var2:-foo} # same thing but more typing

echo "var1 is $var1 | var2 is $var2"

无覆盖值

$ ./override.sh
var1 is foo | var2 is foo

随着覆盖值

$ var1=bar var2=baz ./override.sh
var1 is bar | var2 is baz

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