通过索引访问Shell脚本参数 [英] Accessing shell script arguments by index

问题描述

当您进入shell编程时，我确定这是不费吹灰之力的. 不幸的是我不是，我现在很难过...

I'm sure this is a no-brainer when you're into shell programming. Unfortunately I'm not and I'm having a pretty hard time ...

我需要验证传递给shell脚本的参数. 我还想将所有传递的参数存储在数组中，因为以后需要进一步分离.

I need to verify arguments passed to a shell script. I also want to store all parameters passed in an array as I need further separation later.

我有一个参数"-o"，其后必须为0或1. 因此，我想检查以下参数是否有效. 这是我尝试过的:

I have an argument "-o" which must be followed by either 0 or 1. Thus, I want to check if the following argument is valid. Here's what I tried:

# Loop over all arguments
for i in "$@"
do
    # Check if there is a "-" as first character,
    # if so: it's a parameter
    str="$i"
    minus=${str:0:1}

    # Special case: -o is followed by 0 or 1
    # this parameter needs to be added, too
    if [ "$str" == "-o" ]
    then
        newIdx=`echo $((i+1))`   # <-- problem here: how can I access the script param by a generated index?
        par="$($newIdx)"

        if [[ "$par" != "0" || "$par" != "1" ]]
        then
            echo "script error: The -o parameter needs to be followed by 0 or 1"
            exit -1
        fi
        paramIndex=$((paramIndex+1))

    elif [ "$minus" == "-" ]
    then
        myArray[$paramIndex]="$i"
        paramIndex=$((paramIndex+1))
    fi
done

我尝试了各种方法，但是没有用... 如果有人可以阐明这一点，将不胜感激！

I tried various things but it didn't work ... Would be grateful if someone could shed light on this!

谢谢

推荐答案

在bash中，可以使用间接参数扩展来访问任意位置参数.

In bash, you can use indirect parameter expansion to access an arbitrary positional parameter.

$ set a b c
$ paramIndex=2
$ echo $2
b
$ echo ${!paramIndex}
b

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