Custom icon for specific file type in Nautilus on Ubuntu 22.04

[Wrichik Basu]

My system is Ubuntu 22.04.4; GNOME Shell v42.9

The application is HomeBank, installed via flatpak. The files have an extension .xhb. I want to associate the icon of this application to this file type.

I found the application logo files under /usr/share/icons/hicolor/ZxZ/apps/homebank.png. The available sizes (Z) are 16, 22, 24, 32, 48, 256. There was no scalable .svg icon, but I have built one.

A Google search brought up this answer from AskUbuntu. I'll list what I did step by step. The OP wanted a custom icon for application/x-hwp files. I want it for application/x-homebank files.

1. Edited /etc/mime-types to add the line:

application/x-homebank        xhb

I confirmed the MIME type by right-clicking on a .xhb file → Properties in Nautilus.

2. Created an mimetypes/ directory under /usr/share/icons/gnome/scalable/.

3. Copied the scalable icon as below:

sudo cp /path/to/icon/application-x-homebank.svg /usr/share/icons/gnome/scalable/mimetypes/

4. Restarted GNOME with Alt + F2 → r.

Icons did not change in nautilus.

Found another answer to a similar question on AskUbuntu again. The OP wanted to add custom icons for MATLAB files and figures. Here's what I did:

1. Created the following XML file:
[CODE lang="xml" title="~/homebank.xml"]<?xml version="1.0" encoding="UTF-8"?>
<mime-info xmlns='http://www.freedesktop.org/standards/shared-mime-info'>
<mime-type type="application/x-homebank">
<comment>Homebank data file</comment>
<glob pattern="*.xhb"/>
<icon name="application-x-homebank"/>
</mime-type>
</mime-info>[/CODE]

This XML structure is also shown in the docs of xdg-mime.

2. Ran the following:

sudo xdg-mime install --novendor ./homebank.xml

This added the following file in /usr/share/mime/application/x-homebank.xml:
[CODE lang="xml" title="x-homebank.xml"]<?xml version="1.0" encoding="utf-8"?>
<mime-type xmlns="http://www.freedesktop.org/standards/shared-mime-info" type="application/x-homebank">
<!--Created automatically by update-mime-database. DO NOT EDIT!-->
<comment>Homebank data file</comment>
<glob pattern="*.xhb"/>
<icon name="application-x-homebank"/>
</mime-type>[/CODE]

That probably shows that xdg-mime worked fine.

3. Painstakingly installed the icons, for each of the available sizes listed above, as follows:

sudo xdg-icon-resource install --novendor --noupdate --context mimetypes --size 48 homebank_48.png application-x-homebank

4. The above step also created symlinks. The directory structure of /usr/local/share/icons/hicolor/ is like this:

[CODE lang="bash" title="/usr/local/share/icons/hicolor tree"]
├── 16x16
│ ├── apps
│ │ └── ...
│ └── mimetypes
│ ├── application-x-homebank.png
│ └── gnome-mime-application-x-homebank.png -> application-x-homebank.png
├── 22x22
│ └── mimetypes
│ ├── application-x-homebank.png
│ └── gnome-mime-application-x-homebank.png -> application-x-homebank.png
├── 24x24
│ ├── apps
│ │ └── ...
│ └── mimetypes
│ ├── application-x-homebank.png
│ └── gnome-mime-application-x-homebank.png -> application-x-homebank.png
├── 256x256
│ ├── apps
│ │ ├── ...
│ └── mimetypes
│ ├── application-x-homebank.png
│ └── gnome-mime-application-x-homebank.png -> application-x-homebank.png
├── 32x32
│ ├── apps
│ │ └── ...
│ └── mimetypes
├── 48x48
│ ├── apps
│ │ └── ...
│ └── mimetypes
│ ├── application-x-homebank.png
│ └── gnome-mime-application-x-homebank.png -> application-x-homebank.png
└── scalable
└── mimetypes
├── application-x-homebank.svg
└── gnome-mime-application-x-homebank.svg -> ./application-x-homebank.svg
[/CODE]

The last directory scalable/ was added by me manually because xdg-icon-resource doesn't support scalable icons by default. I did this with:

sudo mkdir scalable
cd scalable
sudo mkdir mimetypes
cd mimetypes
sudo cp ~/path/to/scalable_icon.svg ./application-x-homebank
sudo ln -s ./application-x-homebank.svg ./gnome-mime-application-x-homebank.svg

5. Then ran

sudo xdg-icon-resource forceupdate

6. Restarted Gnome shell.

Nothing. Absolutely no change.

Came across this question on Unix-Linux SE, decided to give it a go. Ran the following:
[code lang="bash"]
update-mime-database ~/.local/share/mime
sudo update-mime-database /usr/share/mime/
update-icon-caches ~/.local/share/icons
sudo update-icon-caches /usr/share/icons/
sudo update-icon-caches /usr/local/share/icons/
[/code]
And, you probably guessed correctly — still nothing.

I am at a loss at this point.

 

[jack action]

Official documentation (assuming the MIME type text/x-python py is already in /etc/mime.types):

Adding an Icon​

Now we need to associate an icon with the MIME type. Get an SVG icon and name it "text-extension.svg", or whatever your modified MIME type is named; this will be the icon to represent all instances of the MIME type on your system. For our python example, this is a good choice. Rename the .svg file so that the it matches "text-x-python.svg" (or "insertYourMIMEtype.svg") so that the slashes are replaced with "-" and there are no capital letters.

Then simply run the following commands, with 'text-x-python' replaced with your MIME type.

sudo cp text-x-python.svg /usr/share/icons/gnome/scalable/mimetypes
sudo gtk-update-icon-cache /usr/share/icons/gnome/ -f

Relogin and all files ending in the MIME extension will display with that icon.

Note that the cache was updated AND you have to logout and relogin.

 

[Wrichik Basu]

Official documentation (assuming the MIME type text/x-python py is already in /etc/mime.types):

Note that the cache was updated AND you have to logout and relogin.

Did that just now. (MIME type was already added to /etc/mime.types)

sudo cp ./application-x-homebank.svg /usr/share/icons/gnome/scalable/mimetypes/
sudo gtk-update-icon-cache /usr/share/icons/gnome/ -f

Still nothing.

 

[jack action]

In your first solution, there was also the following comment:

You also need to check ~/.local. For example ~/.local/share, which mimics the folder /usr/local/share. Your locally installed application (i.e. application for you only, not other logins), may have their properties there. Edit similar files, for example, ~/.local/share/icons/XXXX/XXXX

I know that Chrome added some images on my system in ~/.local/share/icons/hicolor/.

 

[Wrichik Basu]

In your first solution, there was also the following comment:

I know that Chrome added some images on my system in ~/.local/share/icons/hicolor/.

Executing ls -R ~/.local/ | grep homebank returns nothing. Should I put the icon files inside the respective directories in .local too?

 

[jack action]

I've been playing around for a while now trying to change the Python icon on my system and I cannot do it as well. I will follow this thread.

 

[pbuk]

Sounds like fun, I'll have a go too. Quick question:

There was no scalable .svg icon, but I have built one.

Are you sure this is 'proper' SVG and not a bitmap embedded in SVG markup? Have you tried first using some other icon you know works in Nautilus?

 

[Wrichik Basu]

Are you sure this is 'proper' SVG and not a bitmap embedded in SVG markup? Have you tried first using some other icon you know works in Nautilus?

Just to rule out this possibility, I copied the SVG from /usr/share/icons/hicolor/apps/scalable/audacity.svg to all the locations where I had copied the homebank icon. The SVG for Audacity was placed by flatpak, so it should be fine. Updated all icon-caches, logged out and back in. The issue persists.

 

[pbuk]

I haven't made much progress, been having problems with VirtualBox v7 and Ubuntu.

You do realise that the SO thread you are following is more than 10 years old? Gnome has changed a lot in that time.

 

[Wrichik Basu]

You do realise that the SO thread you are following is more than 10 years old? Gnome has changed a lot in that time.

Yeah I know, but there isn't anything more recent available on this. At least I didn't find it via Google.

 

[Wrichik Basu]

So in addition to posting here, I had also posted on GNOME's community help forum. One person told me that this might be because of the theme. So I opened the gnome-tweaks-tool and changed the icon theme to Gnome, and behold! The file icons are precisely what I wanted!

I had earlier used the scalable icon from Audacity to remove any issues with the SVG file itself. I copied the proper SVG to /usr/share/icons/gnome/scalable/mimetypes/application-x-homebank.svg, then logged out and back in. And it worked. The icons for that specific file type have changed.

Edit: The interesting part is that, if I choose Hicolor in the Tweaks tool, the icon in /usr/share/icons/hicolor/scalable/mimetypes/application-x-homebank.svg is activated (verified this by copying the audacity scalable icon as the homebank icon).

Edit 2: The icon theme that I use is Yaru-blue-dark. Quite obviously, creating an icon in /usr/share/icons/Yaru-blue-dark/scalable/mimetypes/application-x-homebank.svg fixed the issue; the files with .xhb extension now have the icon that I would like them to have.