Handler
You will find all the commands the src/server/src/commands/handler folder.
This is the structure that will represent a command.
typedef struct commands_s {
    char *name;
    void (*command)(client_t *client, server_t *server);
} commands_t;
name: the name of the command command: the function pointer that will execute command
If you want to add AI or GUI commands you will need to update one of the 2 defines:
#define NB_AI_COMMANDS 12
#define NB_GUI_COMMANDS 9
Don't forget to update these const variables that contains the commands:
const commands_t commands_gui[NB_GUI_COMMANDS] = {
    {"msz", msz},
    {"bct", bct},
    {"mct", mct},
    {"tna", tna},
    {"ppo", ppo},
    {"plv", plv},
    {"pin", pin},
    {"sgt", sgt},
    {"sst", sst}
};
const commands_t commands_ai[NB_AI_COMMANDS] = {
    {"Forward", forward},
    {"Right", right},
    {"Left", left},
    {"Look", look},
    {"Inventory", inventory},
    {"Broadcast", broadcast},
    {"Connect_nbr", connect_nbr},
    {"Fork", fork_z},
    {"Eject", eject},
    {"Take", take},
    {"Set", set},
    {"Incantation", incantation},
};
If you want to add a Hello World command go here