What is ledger? What are its …

Ledger is a powerful, double-entry accounting system that is accessed from the UNIX command-line. This may put off some users, as there is no flashy UI, but for those who want unparalleled reporting access to their data, there really is no alternative.
Here are some of the features of Ledger which set it apart from other accounting systems:

• Ledger never creates or modifies your data. Your entries are kept in a text file that you maintain, and you can rest assured, no automated tool will ever change that data.
• The amount of data required by Ledger is minimal. It figures out from looking at your data what you mean by it and how you want it reported back to you. Accounts are created as they appear; currencies are created as they’re referenced. Anywhere that a value can be calculated, you can leave it out.
• Ledger is a double-entry accounting tool, meaning that all entries must balance. If an entry does not balance, it will cause an error and the report will not be generated. Ledger is always checking the accuracies of your entries at every run; you won’t ever run into problems with “unaccounted” sums in an account.
• Ledger is 100% currency-agnostic. You can store multiple currencies in any account, convert between them, or even pay in one currency and receive change in another.
• Ledger is international. UTF8 is accepted anywhere in data files, Ledger uses ISO format dates, attaches no meaning to the naming of accounts, and can accept data in either US or European decimal formats. It will report currencies back to you following the manner of your own entries.
• Ledger uses a simple set of base commands which can be extended in countless ways. You can create monthly reports, average reports, check account balances, reconcile accounts, keep track of capital gains on stocks, etc.