Ledger

Ledger is a powerful, double-entry accounting system that is accessed from the UNIX command-line. This may put off some users, since there is no flashy UI, but for those who want unparalleled reporting access to their data there are few alternatives.

Ledger uses text files for input. It reads the files and generates reports; there is no other database or stored state. To use Ledger, you create a file of your account names and transactions, run from the command line with some options to specify input and requested reports, and get output. The output is generally plain text, though you could generate a graph or html instead. Ledger is simple in concept, surprisingly rich in ability, and easy to use.