There are many alternatives to TrueCrypt for Linux and since it's discontinued a lot of people are looking for a replacement. The best Linux alternative is VeraCrypt, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 50 alternatives to TrueCrypt and many of them are available for Linux so hopefully you can find a suitable replacement. Other interesting Linux alternatives to TrueCrypt are Cryptomator (Freemium, Open Source), File Lock PEA (Free, Open Source), LUKS (Free, Open Source) and CipherShed (Free, Open Source).
ImmediateCrypt is an utility for encryption and decryption of plain text messages with the AES-256 cipher. It is released under the GPLv3 license (full Java source available) and works under any Java-enabled environment (Windows, Linux and Mac OSX).
SD4L is a suite of Linux tools and a graphical user interface (GUI) which allow the creation of, and access to ScramDisk encrypted container files. In particular, SD4L provides a Linux driver which enables mounting ScramDisk containers.
Encryption Wizard (EW) is a simple, strong, Java file and folder encryptor for protection of sensitive information. EW encrypts all file types for data-in-transit protection and supplements data-at-rest protection.