让bash遍历未知数量的变量 [英] Let bash loop over unknown number of variables

问题描述

我有一个文件，其中定义了一堆变量.可能是一，四或二十.它们具有诸如 ipt_rss 和 bhd_rss 之类的名称.我们将这些变量称为 var_i

I have a file where a bunch of variables are defined. It could be one, four or twenty. They have names such as ipt_rss and bhd_rss. Let's call these variables var_i

现在，我想让bash像这样循环遍历这些变量:

Now, I'd like to let bash loop over these variables like this:

for all i in var_i do
    command1 arg command2 arg $var_1 > /some/directory/$var_i.rss
        echo "Success finding $var_i"
done

我该怎么做?

推荐答案

如果变量开始都带有通用前缀，则可以遍历所有此类变量名称，并对结果使用间接变量扩展:

If the variables all begin with a common prefix, you can iterate over all such variable names and use indirect variable expansion on the results:

for var in ${!rss_*}; do  # rss_ipt, rss_bhd, etc
    command1 arg command2 arg "${!var}" > "/some/directory/${!var}.rss"
done

否则，您能做的最好的事情就是显式定义一个变量名称数组，或对名称列表进行硬编码:

Otherwise, the best you can do is explicitly define an array of variable names, or hard-code the list of names:

vars=( ipt_rss bhd_rss ... )
for var in "${vars[@]}"; do

或

for var in ipt_rss bhd_rss; do

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