How can I automatically create a link on the desktop or in $HOME when USB Stick is mounted?

Question

How can I create(and remove if unplugged) a symlink to the mount-point of a newly plugged-in USB-device on the desktop or in the $HOME of the systems guest-account?

Answer 1

Your question turns out to exist of two separate questions:

1. How to automatically create (and remove) a link on the desktop to mounted usb drives
2. How to run it on guest account

These questions are answered in [1.] and [2.] below.

1. Automatically create a desktop link to mounted usb drives (in general)

With a small background script, you can automatically have a link created on your desktop to the mounted usb drive(s), and automatically have it removed if the drive is removed.

The procedure; how it works

The script below is an edited version of this one. This version:

• keeps an eye on newly mounted devices (using the command lsblk)
• if a new item shows up, it checks if the newly mounted device is a usb device by the command: find /dev/disk -ls | grep <disk>. If usb in the output, the new mount is valid.
• if the mount is valid, a link is created on the user's desktop, with the command: ln -s <new_mount> <target>.
  The targeted link is named: [USB] <devicename>.

At the same time

• The new mount is added to a list. periodically (once per four seconds), the list is checked. If the mount no longer exists, its corresponding link is removed from your desktop.

How to set up

1. Copy the script below into an empty file, save it as show_usb.py

2. create the directory /opt/show_usb (since we want to run it for a guest account):

   sudo mkdir /opt/show_usb
   

3. Copy the script into /opt/show_usb:

   sudo cp /path/to/show_usb.py /opt/show_usb
   

4. Test-run the script from a terminal by the command:

   python3 /opt/show_usb/show_usb.py
   

5. If all works fine, add it to Startup Applications: Dash > Startup Applications > Add. Add the command:

   python3 /opt/show_usb/show_usb.py
   

The script

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

def find_dtop():
    # get the localized path to the Desktop folder
    home = os.environ["HOME"]; dr_file = home+"/.config/user-dirs.dirs"
    return [home+"/"+ l.split("/")[-1].strip() \
            for l in open(dr_file).readlines() \
            if l.startswith("XDG_DESKTOP_DIR=")][0].replace('"', "")

def get_mountedlist():
    return [(item.split()[0].replace("├─", "").replace("└─", ""),
             item[item.find("/"):]) for item in subprocess.check_output(
            ["lsblk"]).decode("utf-8").split("\n") if "/" in item]

def identify(disk):
    cmd = "find /dev/disk -ls | grep /"+disk
    output = subprocess.check_output(["/bin/bash", "-c", cmd]).decode("utf-8")
    return True if "usb" in output else False

done = []; check = []
dt = find_dtop()
while True:
    mnt = get_mountedlist(); mount_check = [item[1] for item in mnt]
    for item in check:
        if not item in mount_check:
            try:
                os.remove(dt+"/[USB] "+item.split("/")[-1]); check.remove(item)
            except FileNotFoundError:
                pass
    new_paths = [dev for dev in mnt if not dev in done and not dev[1] == "/"]
    valid = [dev for dev in new_paths if identify(dev[0]) == True]
    for item in valid:
        new = item[1]
        subprocess.Popen(["ln", "-s", new, dt+"/[USB] "+new.split("/")[-1] ])
        check.append(new)
    time.sleep(4)
    done = mnt

---

2. How to automatically run the script, specifically in guest account

To make the script autostart in a guest session:

1. Look if the directory /etc/guest-session/skel/.config/autostart exists. If not, create it:

   sudo mkdir -p /etc/guest-session/skel/.config/autostart
   

2. Now create a startup launcher for the guest account:

   sudo -i gedit /etc/guest-session/skel/.config/autostart/desktop_usb.desktop
   

   In the file that opens, paste the code below:

   [Desktop Entry]
   Name=USB_desktop
   Exec=python3 /opt/show_usb/show_usb.py
   Type=Application
   

   Save and close the file. Now when you log in on guest account, the script will run.

That's it

Notes

• More on how to edit the guest account to be found here.
• The script only acts if a new drive is mounted and adds no noticeable load to the processor whatsoever.