在 bash 中循环参数
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looping over arguments in bash
提问by user2223066
In bash, I can loop over all arguments, $@. Is there a way to get the index of the current argument? (So that I can refer to the next one or the previous one.)
在 bash 中，我可以遍历所有参数 $@。有没有办法获得当前参数的索引？（这样我就可以参考下一个或上一个。）
回答by jedwards
Not exactly as you specify, but you can iterate over the arguments a number of different ways.
与您指定的不完全一样，但您可以通过多种不同的方式迭代参数。
For example:
例如：
while test $# -gt 0
do
echo
shift
done
回答by glenn Hymanman
Pretty simple to copy the positional params to an array:
将位置参数复制到数组非常简单：
$ set -- a b c d e # set some positional parameters
$ args=("$@") # copy them into an array
$ echo ${args[1]} # as we see, it's zero-based indexing
b
And, iterating:
并且，迭代：
$ for ((i=0; i<${#args[@]}; i++)); do
echo "$i ${args[i]} ${args[i-1]} ${args[i+1]}"
done
0 a e b
1 b a c
2 c b d
3 d c e
4 e d
回答by Gordon Davisson
You can loop over the argument numbers, and use indirect expansion (${!argnum})to get the arguments from that:
您可以遍历参数编号，并使用间接扩展 ( ${!argnum}) 从中获取参数：
for ((i=1; i<=$#; i++)); do
next=$((i+1))
prev=$((i-1))
echo "Arg #$i='${!i}', prev='${!prev}', next='${!next}'"
done
Note that $0(the "previous" argument to $1) will be something like "-bash", while the "next" argument after the last will come out blank.
请注意$0（ 的“前一个”参数$1）将类似于“-bash”，而最后一个之后的“下一个”参数将显示为空白。
