[Grim_]

There's no need, I've found your problem.

pawn Код:

new cmd[256], idx, file[128], tmp[256], tmp2[256];
cmd = strtok(cmdtext, idx);

This code should be under OnPlayerCommandText, not the /register command itself. (Same goes to the /login command)
Then, you'll also need to change your command lines to

pawn Код:

if(strcmp(cmd, "/register", true) == 0)
if(strcmp(cmd, "/login", true) == 0)

And it should be fixed, try it