command not doing anything when executing

Question

Sketch of situation

I am running a small game server, openttd, on my (headless) raspberry pi 3B. I have been able to play this game, with a huge map, so resources are fine (if you don't mind waiting a bit).

Everytime I run a game, i do so with openttd -D -f to create a new game, and keep it running after i close my SSH connection. Everytime I close a game, i look up the games PID, kill the process, and if I want another game, i start a new one.

Since all that was going smoothly, i decided it was time to automate that repetitive cycle a bit. I started out by filtering the PID of the first command that contained "openttd" out of the ps aux command, like this: ps aux | grep "openttd" | tr -s " " | cut -s -d " " -f 2 | head -n 1. Although not optimal, it works for me. When I tried to test it however, it didn't find any games. When I investigated this, i noticed the following:

My specific problem

Running the command openttd -D -f completes instantly, and with no output. (It should take some time to calculate stuff).

when running openttd -D -f && tail -f ~/.openttd/openttd.cfg nothing happens.
if i run ps aux | grep openttd I don't find any processes.

If i run the command openttd -h which should show (brief) help info, I get no output, and the command completes instantly.

The command is in my path, and is executable. I don't think I changed any config since it ran successfully. I am able to access the man page of the command, and it looks the same as usual.

My generalized question

How do you deal with a command that misbehaves as I described above?
What are things that should be checked?
What are possible causes for this situation?

Answer 1

Check if openttd is what you think it is. Execute

type openttd

or

which openttd

Answer 2

Thanks to Gerard H. Pille, who suggested to check the command path with type openttd or which openttd, I was able to track the source of my error: myself.

When I tried to automate the process of launching/stopping a game, I created a file called "openttd" in /usr/local/bin. The file was executable, but had no content, hence my error.

Renaming the file to something else fixed my issue.