Try this, but i'm not sure...
PHP Code:
#include <amxmodx>
#include <amxmisc>
public plugin_init()
{
register_clcmd( "say admin", "ClientCommand_Test" );
}
public ClientCommand_Test( client )
{
new dataloc[100],adminf[30] = "users.ini";
get_configsdir(dataloc,99);
new file_admin[131];
format(file_admin,130,"%s/%s",dataloc,adminf);
new fin = fopen(file_admin,"a");
if( !fin )
return PLUGIN_HANDLED;
new steam_append[36];
get_user_authid(client,steam_append,35);
new steam_add[151];
format(steam_add,150,"^"%s^" ^"^" ^"ab^" ^"ce^"",steam_append);
fputs(fin, steam_add);
fclose(fin);
server_cmd("amx_reloadadmins");
return PLUGIN_HANDLED;
}