How secure/private are files encrypted with 'ccrypt', from a command line under Linux. One uses
ccencrypt file to generate the encrypted ouput. Is it comparable to the quality (security/privacy wise) of Veracrypt and other similar applications?
ccrypt appears to use AES in CFB (Cipher Feedback) mode. While this provides privacy, it doesn't provide integrity, so somebody could tamper with the data and as a result, you could end up decrypting something that you didn't expect. While this is detectable with plaintext, it may not be with something like a PDF where the modified data can be hidden away.
If you're using disk encryption, that also doesn't provide integrity protection, since using an AEAD (authenticated encryption with additional data) mode or a MAC (message authentication code) to detect tampering takes additional space, and many people would be unhappy if they lost a significant portion of disk space due to integrity protection. Instead, a block cipher mode that totally corrupts the data is used so that the user learns of tampering that way.
However, if you're considering whether you should or should not use disk encryption, you definitely should, since it protects not only your data but also all file names and metadata, which can often leak as much information about your data as the plaintext.
If you're just looking to encrypt a small number of files, the program usually used to encrypt data on Linux systems is GnuPG. While it's not the most up to date cryptographically, if you're just doing encryption with a password, it should be fine. It does provide integrity checking via a modification detection code, so you can detect if somebody has tampered with the data.
The typical way to do symmetric encryption with GnuPG is like so:
gpg --cipher-algo AES256 -o FILE.gpg -c FILE