Just a few notes on creating a TrueCrypt volume, mounting it and unmounting it on Linux.
Note : TrueCrypt is no longer supported, so you should plan your data migration to another tool (after some research I've switched to VeraCrypt (a project that started with the TrueCrypt code after it had passed its security audit) - I leave this page up for historical purposes.
Create a truecrypt volume (must be big enough to contain the file(s) you want to encrypt:
(the volume I created was called test.tc)
Create a mountpoint for the truecrypt volume:
mount the truecrypt volume:
truecrypt test.tc /dev/mapper/truecrypt0
Copy the file(s) to the truecrypt volume:
cp <FILENAMES> /dev/mapper/truecrypt0/
unmount the truecrypt volume
truecrypt -d /dev/mapper/truecrypt0