Under Linux, maybe some files that you don't want to share with others, so the best way is to encrypt the secret files.
Here I introduce a simple way for Ubuntu or other linux users:
First install CFS:
$ apt-get install cfs
Make a folder where you want to keep secret files.
$ cmkdir Secret
Now input your password (At least 16 characters). You have to remember it.
Attach a folder to show the secret context in "Secret" and might add more files to "Secret":
$ cattach Secret tmp
Now input the mentioned password.
Check the context of folder "Secret":
$ cd /crypt/tmp
You will see all files that have been encrypted in "Secret", are now shown in "/crypt/tmp".
Now you can add more files in "/crypt/tmp":
$ cp some.txt /crypt/tmp/
After changing the "/crypt/tmp" folder, you have to encrypt the folder:
§ cdetach tmp
Now the folder "/crypt" become empty. However, you can check the encrypted file is added in "Secret" now.