Linux shell：LOOP用于在每个文件夹中创建文件

Question

experts

I want to create file in each folder . Here is my command

for i in `ls`;do cd $i;touch test.txt;done

-bash: cd: 10/: No such file or directory
-bash: cd: 2/: No such file or directory
-bash: cd: 3/: No such file or directory
-bash: cd: 4/: No such file or directory
-bash: cd: 5/: No such file or directory
-bash: cd: 6/: No such file or directory
-bash: cd: 7/: No such file or directory
-bash: cd: 8/: No such file or directory
-bash: cd: 9/: No such file or directory

It only generate test.txt in folder 1/ , the rest folder are blank. I think the reason is my command lack of { } to clarify the scale of LOOP for .

could you please help me update my command?

Answer 1

for dir in */; do
   touch "$dir/test.txt"
done

1. There's no need to cd into a directory to create a file there.
2. Don't parse the output of ls . The output of ls is only for looking at. Parsing it will break if your files or directories have names containing literal newlines or spaces.
3. The pattern */ will match any directory in the current directory.
4. Quote your variable expansions. Your code would break if IFS is set to a digit.

If you really need to do a cd into the directory, do it in a subshell. The changed working directory only affects the subshell and there is no need to cd back.

for dir in */; do
   ( cd "$dir" && touch test.txt )
done

Answer 2

Let's consider that you have the following 10 folders in your current working directory:

tree .
.
├── 1
├── 10
├── 2
├── 3
├── 4
├── 5
├── 6
├── 7
├── 8
└── 9

you can run the following command, to create your files:

for d in `find . -mindepth 1 -maxdepth 1 -type d`; do touch "$d"/test.txt; done

OUTPUT:

tree .
.
├── 1
│   └── test.txt
├── 10
│   └── test.txt
├── 2
│   └── test.txt
├── 3
│   └── test.txt
├── 4
│   └── test.txt
├── 5
│   └── test.txt
├── 6
│   └── test.txt
├── 7
│   └── test.txt
├── 8
│   └── test.txt
└── 9
    └── test.txt

10 directories, 10 files

Explanations:

find . -mindepth 1 -maxdepth 1 -type d find . -mindepth 1 -maxdepth 1 -type d will get all the folders that are exactly 1 level under your current working folder if you omit -mindepth 1 then you will have a file created in your current working directory since . will be selected, if you omit -maxdepth 1 then file will be created recursively at any depth level, also -type d will allow to filter only on directories.

You can then use a loop to create the files or even xargs command would be enough

Answer 3

You cd into a directory, but you don't cd back out. Assuming that the first directory in the list is 1 , your script first changes into 1 , and next tries to change into 1/10 , which does not exist.

You could do a cd - after touching the file.

Even better, you avoid the cd altogether and do a touch $i/test.txt instead.

Of course, the script as written is not very robust: It breaks, if the current directory contains plain files, and it breaks if it contains entries which have spaces in their names - but this is a different issue.

Answer 4

稍微改变你的命令，

for i in `ls -1`;do touch "$i"/test.txt;done