bash 将字符串列表通过管道输送到 for 循环
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Pipe a list of strings to for loop
提问by rubo77
How do I pass a list to forin bash?
如何for在 bash 中传递列表？
I tried
我试过
echo "some
different
lines
" | for i ; do
echo do something with $i;
done
but that doesn't work. I also tried to find an explanation with manbut there is no man for
但这不起作用。我也试图找到一个解释，man但没有man for
EDIT:
编辑：
I know, I could use whileinstead, but I think I once saw a solution with forwhere they didn't define the variable but could use it inside the loop
我知道，我可以while改用，但我想我曾经看到过一个解决方案，for其中没有定义变量但可以在循环中使用它
回答by Aaron Digulla
This might work but I don't recommend it:
这可能有效，但我不建议这样做：
echo "some
different
lines
" | for i in $(cat) ; do
...
done
$(cat)will expand everything on stdinbut if one of the lines of the echocontains spaces, forwill think that's two words. So it might eventually break.
$(cat)将扩展所有内容，stdin但如果其中一行echo包含空格，for则会认为这是两个词。所以它最终可能会破裂。
If you want to process a list of words in a loop, this is better:
如果要在循环中处理单词列表，最好这样做：
a=($(echo "some
different
lines
"))
for i in "${a[@]}"; do
...
done
Explanation: a=(...)declares an array. $(cmd...)expands to the output of the command. It's still vulnerable for white space but if you quote properly, this can be fixed.
解释：a=(...)声明一个数组。$(cmd...)扩展到命令的输出。它仍然容易受到空白区域的影响，但如果您正确引用，则可以修复。
"${a[@]}"expands to a correctly quoted list of elements in the array.
"${a[@]}"扩展为数组中正确引用的元素列表。
Note: foris a built-in command. Use help for(in bash) instead.
注意：for是一个内置命令。改用help for（在 bash 中）。
回答by Tom Fenech
foriterates over a list of words, like this:
for遍历单词列表，如下所示：
for i in word1 word2 word3; do echo "$i"; done
use a while readloop to iterate over lines:
使用while read循环遍历行：
echo "some
different
lines" | while read -r line; do echo "$line"; done
Here is some useful readingon reading lines in bash.
回答by Caduchon
This seems to work :
这似乎有效：
for x in $(echo a b c); do
echo $x
done
回答by rubo77
This is not a pipe, but quite similar:
这不是管道，但非常相似：
args="some
different
lines";
set -- $args;
for i ; do
echo $i;
done
cause fordefaults to $@if no in seqis given.
如果没有给出for，$@则原因默认为in seq。
maybe you can shorten this a bit somehow?
也许你可以以某种方式缩短一点？
