How to set the first picture of every folder as its folder icon?

1. Automatically change folder icon into the first found image inside

The python script below will change the icon of all folders inside a directory (recursively) into the first found valid image file inside the folder.

The script

#!/usr/bin/env python3
import subprocess
import os
import sys

# --- set the list of valid extensions below (lowercase)
# --- use quotes, *don't* include the dot!
ext = ["jpg", "jpeg", "png", "gif","icns", "ico"]
# ---

dr = sys.argv[1]

for root, dirs, files in os.walk(dr):
    for directory in dirs:
        folder = os.path.join(root, directory)
        try:
            first = min(p for p in os.listdir(folder) 
                        if p.split(".")[-1].lower() in ext)
        except ValueError:
            pass
        else:
              subprocess.Popen([
                  "gvfs-set-attribute", "-t", "string",
                  os.path.abspath(folder), "metadata::custom-icon",
                  "file://"+os.path.abspath(os.path.join(folder, first))
                  ])

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How to use

1. Copy the script into an empty file, save it as change_icon.py
2. In the head of the script, edit, if you like, the list of extensions to be used as valid icon images.

3. Run it with the targeted directory as an argument:

   python3 /path/to/change_icon.py <targeted_directory>
   

That's it!

2. More advanced

...is to make it a right-click option in nautilus:

The script is slightly different then:

#!/usr/bin/env python3
import subprocess
import os

# --- set the list of valid extensions below (lowercase)
# --- use quotes, *don't* include the dot!
ext = ["jpg", "jpeg", "png", "gif", "icns", "ico"]
# ---

# retrieve the path of the targeted folder
current = os.getenv("NAUTILUS_SCRIPT_CURRENT_URI").replace("file://", "").replace("%20", " ")
dr = os.path.realpath(current)

for root, dirs, files in os.walk(dr):
    for directory in dirs:
        folder = os.path.join(root, directory)
        try:
            first = min(p for p in os.listdir(folder) 
                        if p.split(".")[-1].lower() in ext)
        except ValueError:
            pass
        else:
              subprocess.Popen([
                  "gvfs-set-attribute", "-t", "string",
                  os.path.abspath(folder), "metadata::custom-icon",
                  "file://"+os.path.abspath(os.path.join(folder, first))
                  ])

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To use

1. Create, if it doesn't exist yet, the directory

   ~/.local/share/nautilus/scripts
   

2. Copy the script into an empty file, save it in ~/.local/share/nautilus/scripts as set_foldericons (no extension!), and make it executable.

3. Log out and back in, it works.

Notes

• This will change the icon of all folders inside the right-clicked folder, not of the folder itself.
• Since os.path.realpath() is used, this also works if the targeted folder is a link.

EDIT

Undo (reset) the custom icons inside a directory recursively

If, for some reason you'd like to reset the icons inside a folder to their default icon(s), use the script below. Simply:

• copy it into an empty file, save it as reset_icons.py

• run it by the command:

  python3 /path/to/reset_icons.py <target_directory>
  

The script

#!/usr/bin/env python3
import subprocess
import os
import sys

dr = sys.argv[1]

for root, dirs, files in os.walk(dr):
    for directory in dirs:
        folder = os.path.join(root, directory)
        subprocess.Popen([
            "gvfs-set-attribute", os.path.abspath(folder),
            "-t", "unset", "metadata::custom-icon"
            ])

"gvfs-set-attribute" in script 1. will make error in python3 Ubuntu 18.0.4

This tool has been deprecated, use 'gio set' instead.

I change to

"gio", "set"