close, equity
Prints a "closing balances" transaction and an "opening balances"
transaction that bring account balances to and from zero, respectively.
Useful for bringing asset/liability balances forward into a new journal
file, or for closing out revenues/expenses to retained earnings at the
end of a period.

_FLAGS_

The closing transaction transfers balances to "equity:closing balances".
The opening transaction transfers balances from "equity:opening
balances". You can choose to print just one of the transactions by using
the --opening or --closing flag.

If you split your journal files by time (eg yearly), you will typically
run this command at the end of the year, and save the closing
transaction as last entry of the old file, and the opening transaction
as the first entry of the new file. This makes the files self contained,
so that correct balances are reported no matter which of them are
loaded. Ie, if you load just one file, the balances are initialised
correctly; or if you load several files, the redundant closing/opening
transactions cancel each other out. (They will show up in print or
register reports; you can exclude them with a query like
not:desc:'(opening|closing) balances'.)

If you're running a business, you might also use this command to "close
the books" at the end of an accounting period, transferring income
statement account balances to retained earnings. (You may want to change
the equity account name to something like "equity:retained earnings".)

By default, the closing transaction is dated yesterday, the balances are
calculated as of end of yesterday, and the opening transaction is dated
today. To close on some other date, use: hledger close -e OPENINGDATE.
Eg, to close/open on the 2018/2019 boundary, use -e 2019. You can also
use -p or date:PERIOD (any starting date is ignored).

Both transactions will include balance assertions for the
closed/reopened accounts. You probably shouldn't use status or realness
filters (like -C or -R or status:) with this command, or the generated
balance assertions will depend on these flags. Likewise, if you run this
command with --auto, the balance assertions will probably always require
--auto.

When account balances have cost information (transaction prices), the
closing/opening transactions will preserve it, so that eg balance -B
reports will not be affected.

Examples:

Carrying asset/liability balances into a new file for 2019, all from
command line:

_Warning: we use >> here to append; be careful not to type a single >
which would wipe your journal!_

$ hledger close -f 2018.journal -e 2019 assets liabilities --opening >>2019.journal
$ hledger close -f 2018.journal -e 2019 assets liabilities --closing >>2018.journal

Now:

$ hledger bs -f 2019.journal                   # one file - balances are correct
$ hledger bs -f 2018.journal -f 2019.journal   # two files - balances still correct
$ hledger bs -f 2018.journal not:desc:closing  # to see year-end balances, must exclude closing txn

Transactions spanning the closing date can complicate matters, breaking
balance assertions:

2018/12/30 a purchase made in 2018, clearing the following year
    expenses:food          5
    assets:bank:checking  -5  ; [2019/1/2]

Here's one way to resolve that:

; in 2018.journal:
2018/12/30 a purchase made in 2018, clearing the following year
    expenses:food          5
    liabilities:pending

; in 2019.journal:
2019/1/2 clearance of last year's pending transactions
    liabilities:pending    5 = 0
    assets:checking
