You should look in the scripting folder at the sma files for the amxx core plugins..
Code:
public cmdNick(id, level, cid)
{
if (!cmd_access(id, level, cid, 3))
return PLUGIN_HANDLED
new arg1[32], arg2[32], authid[32], name[32], authid2[32], name2[32]
read_argv(1, arg1, 31)
read_argv(2, arg2, 31)
new player = cmd_target(id, arg1, 1)
if (!player)
return PLUGIN_HANDLED
get_user_authid(id, authid, 31)
get_user_name(id, name, 31)
get_user_authid(player, authid2, 31)
get_user_name(player, name2, 31)
client_cmd(player, "name ^"%s^"", arg2)
log_amx("Cmd: ^"%s<%d><%s><>^" change nick to ^"%s^" ^"%s<%d><%s><>^"", name, get_user_userid(id), authid, arg2, name2, get_user_userid(player), authid2)
switch (get_cvar_num("amx_show_activity"))
{
case 2: client_print(0, print_chat, "%L", LANG_PLAYER, "ADMIN_NICK_2", name, name2, arg2)
case 1: client_print(0, print_chat, "%L", LANG_PLAYER, "ADMIN_NICK_1", name2, arg2)
}
console_print(id, "[AMXX] %L", id, "CHANGED_NICK", name2, arg2)
return PLUGIN_HANDLED
}