when running the command x-terminal-emulator, it opens xterm instead of mate terminal, can this be fixed? i have not encountered such an issue before. thanks
Hi @BWaves2019, I wish I had an answer. This issue has been around for quite some time and appears in this 4-year-old related topic.
Summarizing 20.04...
- Executes /usr/bin/x-terminal-emulator
- This is a link to /etc/alternatives/x-terminal-emulator
- This is a link to /usr/bin/lxterm
- This is a script to run xterm version by locale.
So it turns out there are many places to hack it. I invite a developer to comment on the best way and if this might get fixed someday.
Standardize around update-alternatives because it's been there for at least eighteen years and it still works. 
i've seen about this as a way to specify your default. but i've not needed to before, which means it surely should not be set to xterm - for the sake of consistency (and sanity).
in the case of creating a launcher for someone to execute a script in an open terminal window, you dont want to say "oh before that can you do blah blah blah to set the default terminal".
if such a launcher needs to be compatible with multiple ubuntu-based distros, this is an issue, because xterm font is tiny - needing a dedicated command to fix. that in turn could lead to conflict with different resolutions and screen sizes.
i was not expecting the Ubuntu Mate folks to fix it some day, but it would make sense to, overall. anyway, thanks for the replies.
Well, there's a reason for that. But first allow for a correction;
In this guide I've created, which I presume you are referencing the reason x-terminal-emulator.desktop is created, is to make x-terminal-emulator (The terminal as defined in update-alternatives) a selection to be chosen.
Second, the reason why I don't provide files up-front is because in spite my my reputation as a trusted member of this community, it would be — as the kids would say — mad sus to tell people "Hey, download this .desktop file to your root and you can trust me to not mess with your system as you use it!"
That's a recipe for not only multiple warnings, but if not moderated for randoms like you to write a "Useful" guide in this forum telling people to put random junk in their root which could be malicious.
So if you wonder why it's long-winded, inconvenient and slightly convoluted, there's your explanation.