Here's an example of using account aliases.
Say a sole proprietor has a
2014/1/2 expenses:food $1 assets:cash
2014/1/1 expenses:office supplies $1 assets:business checking
So each entity (the business owner, and the business) has their own file with its own simple chart of accounts.
However, at tax reporting time we need to view these as a single entity (at least in the US).
unified.journal, we include both files, and rewrite the personal
account names to fit into the business chart of accounts,
alias expenses = equity:draw:personal alias assets:cash = assets:personal cash include personal.journal end aliases include business.journal
Now we can see the data from both files at once, and the personal account names have changed:
$ hledger -f unified.journal print 2014/01/01 # from business.journal - no aliases applied expenses:office supplies $1 assets:business checking $-1 2014/01/02 # from personal.journal equity:draw:personal:food $1 # <- was expenses:food assets:personal cash $-1 # <- was assets:cash
You can also specify aliases on the command line. This could be useful to quickly rewrite account names when sharing a report with someone else, such as your accountant:
$ hledger --alias 'my earning=income:business' ...
See also Change account name separator.