For those boring with the default ‘Show Applications‘ button in Ubuntu 18.04 left panel, here’s how to replace it with your desired icon without installing a new icon theme.

In Ubuntu 18.04 Gnome Shell, the ‘Show Applications’ button in the bottom-left corner relies on view-app-grid-symbolic.svg icon file located in /usr/share/icons/Adwaita/scalable/actions/.

By replacing the icon file, you’ll get a brand new ‘Show Applications’ icon in the dock.

1. Open terminal either via Ctrl+Alt+T keyboard shortcut, or from applcation menu.

2. Paste the following command and hit run to backup the original icon file:

sudo cp -p /usr/share/icons/Adwaita/scalable/actions/view-app-grid-symbolic.svg /usr/share/icons/Adwaita/scalable/actions/view-app-grid-symbolic.svg.bak

Type user password (no asterisks feedback) when it prompts and hit Enter.

3. Prepare your desired .svg icon file. In my case, it’s gnome-launcher.svg located in my ‘Downloads’ folder.

4. Copy your .svg to the original file location:

sudo cp /path/to/your/svg /usr/share/icons/Adwaita/scalable/actions/view-app-grid-symbolic.svg

In my case, the command is:

sudo cp ~/Downloads/gnome-launcher.svg /usr/share/icons/Adwaita/scalable/actions/view-app-grid-symbolic.svg

5. Finally, run command to refresh the icon cache:

cd /usr/share/icons && sudo gtk-update-icon-cache Adwaita

Or simply log out and login back to apply the change.

How to Restore:

As you’ve made a backup in step 2, simply copy the file back via command:

sudo cp -p /usr/share/icons/Adwaita/scalable/actions/view-app-grid-symbolic.svg.bak /usr/share/icons/Adwaita/scalable/actions/view-app-grid-symbolic.svg

And refresh icon cache or log out and back in.