[Scenario]

This SHOULD work, but it's untested.

pawn Код:

public OnPlayerText(playerid, text[])
{
    if(strfind(text, "/quit") == -1) // if /quit wasn't found...
    {
        if(strfind(text, "/q") != -1) // if /q WAS found...
        {
            new
                pos = strfind(text, "/q"); // get the position of where /q is in the string
                
            strins(text, "uit", pos+2); // add "uit" after /q in the string
        }
    }
    return 1;
}