Hi community, i'm developing a datalogger with the CAN-Bus Shield by sparkfun, for this i need to create several files, one each time the datalogger start a new cycle and save them into the SD card, to distinguish the files i need to name them with date an hour, something like this:
0610215/953.txt where the first number is the date and the second one after the slash is the hour
my cuestions:
Can i create several files with diferent names?
This names can be the date and hour?
How do i do the arduino count date and hour?
I'm sorry for my english, i hope you understand me and helpme, thanks! 
Yes you can create multiple files.
Yes you can use numbers to create the file name (eg, 201510042119.txt), but not the '/' character. I would recommend that you use year, month, date, hour, minute and second in that order so that the file names sort properly in date/time order when they are listed.
The Arduino does not have a clock built in and counting milliseconds is not accurate enough. You will need to use an external clock module (Real Time Clock or RTC).
The SD library only allows filenames in 8.3 format so a name like 201510042119.txt will fail.
IIRC there is a new version of the SdFat library which can handle long names but I've never used it.
You could use a directory and file structure of the form /YYYY/MM/DDHHMM.csv. When creating a new file, you first have to make sure that the path /YYYY/MM exists. If it doesn't, use a call like sd.mkdir("/YYYY/MM") which will make either or both directories in the path as needed. Then you can open and write to /YYYY/MM/DDHHMM.csv
Pete
thank you guys, do you got and example to create multiple files .txt only with arduino and sd shield?, all witout a pc
You could use a system like this:
Symbol: 0 1 2 3 4 5 6 7 8 9 A B C D E F
Number: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Symbol: G H J K L M N P Q R S T U V W X
Number: 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
(The letters I and O are not used.)
If you use this system, then the month, day, and hour could each be one letter.
Example: 8 October 2015 at 14:10 becomes 15A8E10
That way, you only need 7 characters for your filename.
i like your system, now i need to know how to create files with arduino, i already know how to write and erase inside a file but no HOW TO CREATE THE FILE... but... i will use your system 
thanks for the idea
Don't you just open a file and it gets created if it does not exist? Or are you meaning something else? There are examples all over the place to copy.
Have a look at the ReadWrite example sketch in the SD library.
It opens the file for writing like this:
myFile = SD.open("test.txt", FILE_WRITE);
IIRC, if the file doesn't exist it will be created. If it does exist, it will be truncated to zero length.
If you create all the files in the root directory, you will be limited to 512 files in total (again, IIRC). If you're creating a new file every minute this will only allow less than nine hours worth of data before the root directory is full.
If you create a directory structure as I mentioned previously, you can get an essentially infinite number of files.
Pete
thank you pete, i dont know about that and it's totally usefull! thanks again 
the latest sdfat library supports long filenames. So you can use your original naming convention without filename length limitation. If you want to take it one step further, (I assume you are using RTC to keep track of time), you can add a callback to get timestamp so the file entry will have the correct timestamp in the filesystem.