a tale of two errors. I use zsh as my shell. Here’s what I see:
$ curl 0:8998/helloworld?apikey=445
zsh: no matches found: 0:8998/helloworld?apikey=445
$ curl 0:8998/helloworld\?apikey=445
curl: (7) Failed to connect to 0.0.0.0 port 8998 after 0 ms: Couldn't connect to server
The first error is from zsh. It is trying to interpret ? as a wildcard character to match a filename. This is probably not what you want. So the error is expected and is telling you that the sequence that includes a question mark is not matching any files.
I can tell zsh to just treat the? as a question mark, which is what I want, by prefixing it with a backslash. The 2nd command does that. I get a different error this time, from curl. It’s saying it cannot connect to the server running at address 0 (0.0.0.0), at port 8998. This is expected; I have no local server running there. (You may have a server running there on your machine, as part of the tutorial work you’ve done).