在Bash中循环遍历目录 [英] Looping over directories in Bash

问题描述

我有一个关于bash的工作原理的基本问题，以及一个相关的实际问题.

I have a fundamental question about how bash works, and a related practical question.

基本问题:假设我在一个包含三个子目录的目录中:a，b和c.

Fundamental question: suppose I am in a directory that has three subdirectories: a, b, and c.

输入验证码

for dir in $(ls)
do 
    echo $dir
done

吐出来:

a b c
a b c
a b c

即dir始终将所有文件/目录的列表存储在我的cwd中.我的问题是:为什么这在世界上会很方便?我认为一次dir一次存储每个元素会更加有用和直观，也就是说，我希望输出

i.e, dir always stores a list of all of the files/directories in my cwd. My question is: why in the world would this be convenient? In my opinion it is far more useful and intuitive to have dir store each element at a time, i.e I would want to have output

a
b
c

此外，根据答案之一-使用for dir in $(ls)是错误的，但是当我使用for dir in $(ls -l)时，我会得到甚至更多的a b c副本(超过了cwd中的目录/文件).为什么会这样?

Also, as per one of the answers - it is wrong to use for dir in $(ls), but when I use for dir in $(ls -l) I get even more copies of a b c (more than there are directories/files in the cwd). Why is that?

我的第二个问题很实际:我如何遍历cwd中所有以大写字母W开头的目录(不是文件！)?我从

My second question is practical: how do I loop over all the directories (not files!) in my cwd that start with capital W? I started with

for dir in `ls -l W*`

但这失败了，因为a)问题1的原因和b)因为它不排除文件.建议表示赞赏.

but this fails because a) the reason in question 1 and b) because it doesn't exclude files. Suggestions appreciated.

推荐答案

永远不要这样解析ls的输出(为什么不应该't解析ls(1)的输出.

Never ever parse the output of ls like this (Why you shouldn't parse the output of ls(1)).

此外，您的语法错误.您的意思不是()，您的意思是$().

Also, your syntax is wrong. You don't mean (), you mean $().

话虽如此，您可以执行以W开头的目录循环(或根据情况使用find命令):

That being said, to loop over directories starting with W you would do (or use the find command instead, depending on your scenario):

for path in /my/path/W*; do
    [ -d "${path}" ] || continue # if not a directory, skip
    dirname="$(basename "${path}")"
    do_stuff
done

对于您从邪恶的ls循环获得的输出，它看起来应该不是这样.这是预期的输出，并说明了为什么您不想在一开始就使用ls:

As for the output you get from the evil ls-loop, it should not look like that. This is the expected output and demonstrates why you do not want to use ls in the first place:

$ find
.
./c
./a
./foo bar
./b

$ type ls
ls is hashed (/bin/ls)

$ for x in $(ls); do echo "${x}"; done
a
b
c
foo
bar

这篇关于在Bash中循环遍历目录的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！