如何在Bash中更改命令行参数? [英] How to change a command line argument in Bash?

问题描述

有没有一种方法可以更改Bash脚本中的命令行参数.例如，以下列方式调用Bash脚本:

Is there a way to change the command line arguments in a Bash script. Say for example, a Bash script is invoked the following way:

./foo arg1 arg2  

是否可以在脚本中更改arg1的值?说，像

Is there a way to change the value of arg1 within the script? Say, something like

$1="chintz"

推荐答案

您必须重置所有参数.改变例如$3:

You have to reset all arguments. To change e.g. $3:

$ set -- "${@:1:2}" "new" "${@:4}"

基本上，您设置 所有参数设为当前值，但您要更改的参数除外. POSIX 7还 指定了set --.

Basically you set all arguments to their current values, except for the one(s) that you want to change. set -- is also specified by POSIX 7.

"${@:1:2}"表示法是从偏移量1(即$1)开始扩展到两个位置参数(因此用符号2表示).在这种情况下，它是"$1" "$2"的简写，但是当您要替换例如时，它会更有用. "${17}".

The "${@:1:2}" notation is expanded to the two (hence the 2 in the notation) positional arguments starting from offset 1 (i.e. $1). It is a shorthand for "$1" "$2" in this case, but it is much more useful when you want to replace e.g. "${17}".

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