moving files from a folder into subfolders based on the prefix number with Linux-CodePudding

I'm relatively new to bash and I have tried multiples solutions that I could find here but none of them seem to be working in my case. It's pretty simple, I have a folder that looks like this:

- images/
   - 0_image_1.jpg
   - 0_image_2.jpg
   - 0_image_3.jpg
   - 1_image_1.jpg
   - 1_image_2.jpg
   - 1_image_3.jpg

and I would like to move these jpg files into subfolders based on the prefix number like so:

- images_0/
   - 0_image_1.jpg
   - 0_image_2.jpg
   - 0_image_3.jpg

- images_1/
   - 1_image_1.jpg
   - 1_image_2.jpg
   - 1_image_3.jpg

Is there a bash command that could do that in a simple way ? Thank you

CodePudding user response：

for src in *_*.jpg; do
  dest=images_${src%%_*}/
  echo mkdir -p "$dest"
  echo mv -- "$src" "$dest"
done

Remove both echos if the output looks good.

CodePudding user response：

I would do this with rename a.k.a. Perl rename. It is extremely powerful and performant. Here's a command for your use case:

rename --dry-run -p '$_="images_" . substr($_,0,1) . "/" . $_'  ?_*jpg

Let's dissect that. At the right end, we specify we only want to work on files that start with a single character/digit before an underscore so we don't do damage trying to apply the command to files it wasn't meant for. Then --dry-run means it doesn't actually do anything, it just shows you what it would do - this is a very useful feature. Then -p which handily means "create any necessary directories for me as you go". Then the meat of the command. It passes you the current filename in a variable called $_ and we then need to create a new variable called $_ to say what we want the file to be called. In this case we just want the word images_ followed by the first digit of the existing filename and then a slash and the original name. Simples!

Sample Output

'0_image_1.jpg' would be renamed to 'images_0/0_image_1.jpg'
'0_image_2.jpg' would be renamed to 'images_0/0_image_2.jpg'
'1_image_3.jpg' would be renamed to 'images_1/1_image_3.jpg'

Remove the --dry-run and run again for real, if the output looks good.

Using rename has several benefits:

that it will warn and avoid any conflicts if two files rename to the same thing,
that it can rename across directories, creating any necessary intermediate directories on the way,
that you can do a dry run first to test it,
that you can use arbitrarily complex Perl code to specify the new name.

Note: On macOS, you can install rename using homebrew:

brew install rename

Note: On some Ones, rename is referred to as prename for Perl rename.

CodePudding user response：

What about this:

$ for file in $(ls images/*.jpg | cut -d/ -f2); do
        newdir="images_${file:0:1}"
        [[ ! -d  "$newdir" ]] && mkdir $newdir
        mv "images/$file" "$newdir"
done

Assuming the image filename has single digit prefix, newdir name is formed by appending a suffix of the first character of the filename (${file:0:1} - 0 is the offset and length is 1). And if directory newdir does not exist, create one. Finally, move file from old to new.

If the filename could have a multi-digit prefix like 10_image.jpg, use this:

for file in $(ls images/*.jpg | cut -d/ -f2); do
    newdir="images_$(echo $file | cut -d_ -f1)"
    [[ ! -d  "$newdir" ]] && mkdir "$newdir"
    mv "images/$file" "$newdir"
done