I have a folder named /home/user/temps which has 487 folders. In each folder I have a file called thumb.png.

I want to copy all files named thumb.png to a separate folder and rename them based on the folder they came from.

  • rename them, how? If you replace the directory delimiter with something - let's say underline (_), you may get collisions with files, which already contain an underline. That's true for every valid character, and beside / and \0, which are forbidden in filenames, there is no safe harbor - any character might produce a collision. Commented Apr 20, 2011 at 16:46
  • Do folders have subfolders, or just a plain, wide folderstructure? Commented Apr 20, 2011 at 17:06

6 Answers 6


Here you go:

for file in /home/user/temps/*/thumb.png; do new_file=${file/temps/new_folder}; cp "$file" "${new_file/\/thumb/}"; done;


the canonical wisdom, by the way, is that using find for this is a bad idea -- simply using shell expansion is much more reliable. Also, this assumes bash, but I figure that's a safe assumption :)

edit 2:

for clarity, I'll break it down:

# shell-expansion to loop specified files
for file in /home/user/temps/*/thumb.png; do

    # replace 'temps' with 'new_folder' in the path
    # '/home/temps/abc/thumb.png' becomes '/home/new_folder/abc/thumb.png'

    # drop '/thumb' from the path
    # '/home/new_folder/abc/thumb.png' becomes '/home/new_folder/abc.png'
    cp "$file" "${new_file/\/thumb/}";

details on the ${var/Pattern/Replacement} construct can be found here.

the quotes in the cp line are important to handle spaces and newlines etc. in filenames.

  • new_file=new_folder? What's the purpose of the backslash in front of the slash in new_file/\/thumb? Commented Apr 20, 2011 at 17:07
  • 1
    @user: ${VARIABLE/PATTTERN/REPLACEMENT} produces the value of VARIABLE but with the pattern replaces by the replacement text. Here the pattern is /thumb (the / needs to be escaped so that it doesn't look like ${new_file//PATTERN/REPLACEMENT}, which makes it a global replacement instead of a first-occurrence replacement) and the replacement text is empty. Commented Apr 20, 2011 at 20:43
  • Of course, now I see it. :) Commented Apr 20, 2011 at 21:11
  • 1
    You're assuming that the 487 directories are directly under /home/user/temps, which is not clear from the question. If they aren't, you need find or **. Commented Apr 21, 2011 at 7:00
  • @Gilles -- I am indeed, that's how I read the question. Appreciate the point, though :)
    – simon
    Commented Apr 21, 2011 at 8:18

This solution "flattens" the files in sub- and subsubdirectories so they all sit in one big directory. The new file name reflects the original path. For example temps/dir/subdir/thumb.png will become newdir/temps_dir_subdir_thumb.png.

find temps/ -name "thumb.png" |
  while IFS= read -r f do
    cp -v "$f" "newdir/${f//\//_}"

The directories temps and newdir must exists. And you must execute the command from the parent directory of temps and newdir.

The command can also be done in one line

find temps/ -name "thumb.png" | while IFS= read -r f; do cp -v "$f" "newdir/${f//\//_}"; done

note the semicolons (;) where the newlines used to be.

example output

$ find temps/ -name "thumb.png" | while IFS= read -r f; do cp -v "$f" "newdir/${f//\//_}"; done
`temps/thumb.png' -> `newdir/temps_thumb.png'
`temps/dir3/thumb.png' -> `newdir/temps_dir3_thumb.png'
`temps/dir3/dir31/thumb.png' -> `newdir/temps_dir3_dir31_thumb.png'
`temps/dir3/dir32/thumb.png' -> `newdir/temps_dir3_dir32_thumb.png'
`temps/dir1/thumb.png' -> `newdir/temps_dir1_thumb.png'
`temps/dir2/thumb.png' -> `newdir/temps_dir2_thumb.png'
`temps/dir2/dir21/thumb.png' -> `newdir/temps_dir2_dir21_thumb.png'

If you are unsure then prepend echo to cp to see what is going to be executed.

find  temps/ -name "thumb.png" | while IFS= read -r f; do echo cp -v "$f" "newdir/${f//\//_}"; done


This works using parameter expansion: ${f//\//_}. It takes the content of the variable f (which contains the filename with path) and replaces every occurence of / with _.

Note that this is a dumb text search and replace. If two distinct files end up with the same name one of the files will be overwriten.

For example two files temps/dir/thumb.png and temps/dir_thumb.png. Both files will be renamed to temps_dir_thumb.png. So one file will be lost. Which file will be lost is dependent on the order of how find found them on disk.

Obligatory pedantic warning: if your filenames contain newlines this command will break horribly.

  • Fails on files which contain a newline in their name. Commented Apr 20, 2011 at 21:29
  • Well that worked very well . one thing more , i have few zip files in some sub directories as well . is it possible to extract imgae from there as well . remember 'zip not tar'
    – Mirage
    Commented Apr 21, 2011 at 13:45

You can find, copy, and rename files in oneliner command with -exec sh:

find /home/user/temps -name thumb.png \
-exec sh -c 'cp "{}" "$(basename "$(dirname "{}")")_$(basename "{}")"' \;

(The extra " are meant to deal with copying files with spaces).

Option 2 - with xargs (it can print each command before it is executed):

find /home/user/temps -name thumb.png \
| xargs -I {} --verbose sh -c 'cp "{}" "$(basename "$(dirname "{}")")_$(basename "{}")"'

sh -c cp "temps/thumb.png" "$(basename "$(dirname "temps/thumb.png")")_$(basename "temps/thumb.png")"

sh -c cp "temps/dir one/thumb.png" "$(basename "$(dirname "temps/dir one/thumb.png")")_$(basename "temps/dir one/thumb.png")"

sh -c cp "temps/dir two/thumb.png" "$(basename "$(dirname "temps/dir two/thumb.png")")_$(basename "temps/dir two/thumb.png")"


Short helper code:

# echo cp "$1" ../tmp/"${1//\//_}" 
mv "$1" ../tmp/"${1//\//_}"

let's name it 'deslash.sh' and make it executable. Call it with:

find -type f -name thumb.png -exec ./deslash.sh {} ";"    

It will fail, if a collision exists

a/b/thumb.png # and 

but that's unavoidable.


Try this

mkdir /home/user/thumbs

cd /home/user/temps

find . -type d | 
 while IFS="" read -r dir ; do
   if [[ -f "${dir}"/thumb.png ]] ; then
     echo mv -i "${dir}/thumb.png" "${targDir}/${dir}_thumb.png"


I have added quoting in case any of your dir names have white-space chars embedded in them.

Also I have changed this so it will only print out the commands to be executed. Examine the output of the script to be sure all files/path names look proper. When you're sure there are no issues with the commands that will be executed, remove the echo.

  • I have some png files in some more subfolders , will that work
    – Mirage
    Commented Apr 20, 2011 at 14:43
  • for my "A A"-folder, it produces: mv -i ./A A/thumb.png ../tmp/.png - all files end in ../tmp/.png (../tmp is my target dir). Commented Apr 20, 2011 at 17:14
  • Add quotes and curly braces around all variables in above code, i.e. "${dir}"
    – shellter
    Commented Apr 20, 2011 at 18:45
  • @Mirror51 wrote : " files in some more subfolders , will that work ". Yes it should. Did you know you can execute each step of this script separately (or when piped together, each set of pipes). You can execute just the find -type d and see the output. Does that get all the directories you expect? It should, if not, please add some output to show the problem. Good Luck.
    – shellter
    Commented Apr 20, 2011 at 20:33
  • Won't work. read dir performs word splitting, and takes, from a directory a\nb a and b as two instances, which no masking can solve. Commented Apr 20, 2011 at 21:42

To copy you need the command cp, and to rename for linux is the same than moving the file, so you have to do it with mv command. In Linux you always have to specify the whole path, from the source, if you are in another folder, and to the destination folder, of course. I'd be something like this, for copy:

cp /source_path/file /destination_path/

or to rename or move

mv /source_path/old_file /destination_path/new_name_file
  • This is only a minor part of the poster's question. Now explain how to iterate over the directories and copy the thumbnails :-)
    – DarkDust
    Commented Apr 20, 2011 at 13:38
  • the OP wants to use find
    – pavium
    Commented Apr 20, 2011 at 13:38
  • 1
    Yes, you're right... I don't know what happened to me...
    – elvenbyte
    Commented Apr 20, 2011 at 13:40

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .