

Even though the days are named differently in spanish, we still have the same problem. We have 2 days that start with M: “martes” and “miércoles”. Luckily, someone noticed it was an issue and it’s common to use an X for “miércoles” (instead of LMMJVSD, calendars often use LMXJVSD). I find it kinda neat.



The number is the signal you send to the program. There’s a lot of signals you can send (not just 15 and 9).
The difference between them is that 15 (called SIGTERM) tells the program to terminate by itself (so it can store its cached data, create a save without losing data or corrupting, drop all its open connections gracefully, etc). 9 (called SYGKILL) will forcefully kill a program, without waiting for it to properly close.
You normally should send signal 15 to a program, to tell it to stop. If the program is frozen and it’s not responding or stopping, you then send signal 9 and forcefully kill it. No signal is “better” than the other, they just have different usecases.