ledger/doc/L3-Syntax.texi

@c -*-texinfo-*-

@chapter Command-line Syntax
@section Cookbook

@subsection Invoking Ledger

@example
ledger --group-by "tag('trip')" bal
legder reg --sort "tag('foo')" %foo
ledger cleared VWCU NFCU Tithe Misentry
ledger register Joint --uncleared
ledger register NFCUChecking  --sort d  -d 'd>[2011/04/01]' until 2011/05/25
@end example
@subsection Ledger Files

@example
= /^Income:Taxable/ 
  (Liabilities:Tithe Owed)    -0.1
= /Noah/ 
  (Liabilities:Tithe Owed)    -0.1
= /Jonah/ 
  (Liabilities:Tithe Owed)    -0.1
= /Tithe/
  (Liabilities:Tithe Owed)    -1.0
@end example


@section Quick Reference

This chapter describes @ledgerprog's features and serves as a quick
reference. You may wish to survey this to get an overview before diving
in to the @ref{Ledger Tutorial} and more detailed examples that follow.

@ledgerprog@ has a very simple command-line interface, named---enticingly
enough---@command{ledger}.  It supports a few reporting commands, and
a large number of options for refining the output from those commands.
The basic syntax of any ledger command is:

@example
ledger [OPTIONS...] COMMAND [ARGS...]
@end example

Command options must always precede the command word.  After the
command word there may appear any number of arguments.  For most
commands, these arguments are regular expressions that cause the
output to relate only to postings matching those regular
expressions.  For the @command{transaction} command, the arguments have a
special meaning, described below.

The regular expressions arguments always match the account name that a
posting refers to.  To match on the payee of the transaction instead,
precede the regular expression with @samp{--}.  For example, the
following balance command reports account totals for rent, food and
movies, but only those whose payee matches Freddie:

@example
ledger bal rent food movies -- freddie
@end example

There are many, many command options available with the
@command{ledger} command, and it takes a while to master them.
However, none of them are required to use the basic reporting
commands.

@menu
* Commands::                    
* Options::                     
* Period expressions::          
* Format strings::              
* Value expressions::           
* File format::                 
@end menu

@node Commands, Options, Quick Reference, Quick Reference
@section Commands

@subsection balance

The @command{balance} command reports the current balance of all
accounts.  It accepts a list of optional regexps, which confine the
balance report to the matching accounts.  If an account contains
multiple types of commodities, each commodity's total is reported
separately.

@subsection register

The @command{register} command displays all the postings occurring
in a single account, line by line.  The account regexp must be
specified as the only argument to this command.  If any regexps occur
after the required account name, the register will contain only those
postings that match.  Very useful for hunting down a particular
posting.

The output from @command{register} is very close to what a typical
checkbook, or single-account ledger, would look like.  It also shows a
running balance.  The final running balance of any register should
always be the same as the current balance of that account.

If you have Gnuplot installed, you may plot the amount or running
total of any register by using the script @file{report}, which is
included in the @ledgerprog@ distribution.  The only requirement is that you
add either @option{-j} or @option{-J} to your register command, in
order to plot either the amount or total column, respectively.

@subsection print

The @command{print} command prints out ledger transactions in a textual
format that can be parsed by @ledgerprog@.  They will be properly formatted,
and output in the most economic form possible.  The ``print'' command
also takes a list of optional regexps, which will cause only those
postings which match in some way to be printed.

The @command{print} command can be a handy way to clean up a ledger
file whose formatting has gotten out of hand.

@subsection output

The @command{output} command is very similar to the @command{print}
command, except that it attempts to replicate the specified ledger
file exactly.  The format of the command is:

@example
ledger -f FILENAME output FILENAME
@end example

Where @file{FILENAME} is the name of the ledger file to output.  The
reason for specifying this command is that only transactions contained
within that file will be output, and not an included transactions (as can
happen with the @command{print} command).

@subsection xml

The @command{xml} command outputs results similar to what
@command{print} and @command{register} display, but as an XML form.
This data can then be read in and processed.  Use the
@option{--totals} option to include the running total with each
posting.

@subsection emacs

The @command{emacs} command outputs results in a form that can be read
directly by Emacs Lisp.  The format of the sexp is:

@example
((BEG-POS CLEARED DATE CODE PAYEE
  (ACCOUNT AMOUNT)...)  ; list of postings
 ...)                   ; list of transactions
@end example

@subsection equity

The @command{equity} command prints out accounts balances as if they
were transactions.  This makes it easy to establish the starting balances
for an account, such as when @ref{Archiving previous years}.

@subsection prices

The @command{prices} command displays the price history for matching
commodities.  The @option{-A} flag is useful with this report, to
display the running average price, or @option{-D} to show each price's
deviation from that average.

There is also a @command{pricesdb} command which outputs the same
information as @command{prices}, but does in a format that can be
parsed by @ledgerprog@.

@subsection xact

The @command{xact} commands simplifies the creation of new transactions.
It works on the principle that 80% of all postings are variants of
earlier postings.  Here's how it works:

Say you currently have this posting in your ledger file:

@smallexample
2004/03/15 * Viva Italiano
    Expenses:Food                       $12.45
    Expenses:Tips                        $2.55
    Liabilities:MasterCard             $-15.00
@end smallexample

Now it's @samp{2004/4/9}, and you've just eating at @samp{Viva
Italiano} again.  The exact amounts are different, but the overall
form is the same.  With the @command{xact} command you can type:

@example
ledger xact 2004/4/9 viva food 11 tips 2.50
@end example

This produces the following output:

@smallexample
2004/04/09 Viva Italiano
    Expenses:Food                       $11.00
    Expenses:Tips                        $2.50
    Liabilities:MasterCard             $-13.50
@end smallexample

It works by finding a past posting matching the regular expression
@samp{viva}, and assuming that any accounts or amounts specified will
be similar to that earlier posting.  If @ledgerprog@ does not succeed in
generating a new transaction, an error is printed and the exit code is set
to @samp{1}.

There is a shell script in the distribution's @file{scripts} directory
called @file{xact}, which simplifies the task of adding a new transaction
to your ledger.  It launches @command{vi} to confirm that the transaction
looks appropriate.

Here are a few more examples of the @command{xact} command, assuming
the above journal transaction:

@example
ledger xact 4/9 viva 11.50
ledger xact 4/9 viva 11.50 checking # (from `checking')
ledger xact 4/9 viva food 11.50 tips 8
ledger xact 4/9 viva food 11.50 tips 8 cash
ledger xact 4/9 viva food $11.50 tips $8 cash
ledger xact 4/9 viva dining "DM 11.50"
@end example

@node Options, Period expressions, Commands, Quick Reference
@section Options

With all of the reports, command-line options are useful to modify the
output generated.  These command-line options always occur before the
command word.  This is done to distinguish options from exclusive
regular expressions, which also begin with a dash.  The basic form for
most commands is:

@example
ledger [OPTIONS] COMMAND [REGEXPS...] [-- [REGEXPS...]]
@end example

The @var{OPTIONS} and @var{REGEXPS} expressions are both optional.
You could just use @samp{ledger balance}, without any options---which
prints a summary of all accounts.  But for more specific reporting, or
to change the appearance of the output, options are needed.

@subsection Basic options

These are the most basic command options.  Most likely, the user will
want to set them using environment variables (see @ref{Options}),
instead of using actual command-line options:

@option{--help} (@option{-h}) prints a summary of all the options, and
what they are used for.  This can be a handy way to remember which
options do what.  This help screen is also printed if ledger is run
without a command.

@option{--version} (@option{-v}) prints the current version of ledger
and exits.  This is useful for sending bug reports, to let the author
know which version of ledger you are using.

@option{--file FILE} (@option{-f FILE}) reads FILE as a ledger file.
This command may be used multiple times.
Typically, the environment variable
@env{LEDGER_FILE} is set, rather than using this command-line option.

@option{--output FILE} (@option{-o FILE}) redirects output from any
command to @var{FILE}.  By default, all output goes to standard
output.

@option{--init-file FILE} (@option{-i FILE}) causes FILE to be read by
ledger before any other ledger file.  This file may not contain any
postings, but it may contain option settings.  To specify options
in the init file, use the same syntax as the command-line, but put each
option on it's own line.  Here's an example init file:

@smallexample
--price-db ~/finance/.pricedb
--cache /tmp/ledger-cache

; ~/.ledgerrc ends here
@end smallexample

Option settings on the command-line or in the environment always take
precedence over settings in the init file.

@option{--cache FILE} identifies FILE as the default binary cache
file.  That is, if the ledger files to be read are specified using the
environment variable @env{LEDGER_FILE}, then whenever a command is
finished a binary copy will be written to the specified cache, to
speed up the loading time of subsequent queries.  This filename can
also be given using the environment variable @env{LEDGER_CACHE}, or by
putting the option into your init file.  The @option{--no-cache}
option causes @ledgerprog@ to always ignore the binary cache.

@option{--account NAME} (@option{-a NAME}) specifies the default
account which QIF file postings are assumed to relate to.

@subsection Report filtering

These options change which postings affect the outcome of a
report, in ways other than just using regular expressions:

@option{--current}(@option{-c}) displays only transactions occurring on or
before the current date.

@option{--begin DATE} (@option{-b DATE}) constrains the report to
transactions on or after @var{DATE}.  Only transactions after that date will be
calculated, which means that the running total in the balance report
will always start at zero with the first matching transaction.  (Note: This
is different from using @option{--display} to constrain what is
displayed).

@option{--end DATE} (@option{-e DATE}) constrains the report so that
transactions on or after @var{DATE} are not considered.  The ending date
is inclusive.

@option{--period STR} (@option{-p STR}) sets the reporting period
to @var{STR}.  This will subtotal all matching transactions within each
period separately, making it easy to see weekly, monthly, quarterly,
etc., posting totals.  A period string can even specify the
beginning and end of the report range, using simple terms like ``last
june'' or ``next month''.  For more using period expressions, see
@ref{Period expressions}.

@option{--period-sort EXPR} sorts the postings within each
reporting period using the value expression @var{EXPR}.  This is most
often useful when reporting monthly expenses, in order to view the
highest expense categories at the top of each month:

@example
ledger -M --period-sort -At reg ^Expenses
@end example

@option{--cleared} (@option{-C}) displays only postings whose transaction
has been marked ``cleared'' (by placing an asterix to the right of the
date).

@option{--uncleared} (@option{-U}) displays only postings whose
transaction has not been marked ``cleared'' (i.e., if there is no asterix to
the right of the date).

@option{--real} (@option{-R}) displays only real postings, not
virtual.  (A virtual posting is indicated by surrounding the
account name with parentheses or brackets; see the section on using
virtual postings for more information).

@option{--actual} (@option{-L}) displays only actual postings, and
not those created due to automated postings.

@option{--related} (@option{-r}) displays postings that are
related to whichever postings would otherwise have matched the
filtering criteria.  In the register report, this shows where money
went to, or the account it came from.  In the balance report, it shows
all the accounts affected by transactions having a related posting.
For example, if a file had this transaction:

@smallexample
2004/03/20 Safeway
    Expenses:Food                       $65.00
    Expenses:Cash                       $20.00
    Assets:Checking                    $-85.00
@end smallexample

And the register command was:

@example
ledger -r register food
@end example

The following would be output, showing the postings related to the
posting that matched:

@smallexample
2004/03/20 Safeway              Expenses:Cash               $-20.00      $-20.00
                                Assets:Checking              $85.00       $65.00
@end smallexample

@option{--budget} is useful for displaying how close your postings
meet your budget.  @option{--add-budget} also shows unbudgeted
postings, while @option{--unbudgeted} shows only those.
@option{--forecast} is a related option that projects your budget into
the future, showing how it will affect future balances.
@xref{Budgeting and forecasting}.

@option{--limit EXPR} (@option{-l EXPR}) limits which postings
take part in the calculations of a report.

@option{--amount EXPR} (@option{-t EXPR}) changes the value expression
used to calculate the ``value'' column in the @command{register}
report, the amount used to calculate account totals in the
@command{balance} report, and the values printed in the
@command{equity} report.  @xref{Value expressions}.

@option{--total EXPR} (@option{-T EXPR}) sets the value expression
used for the ``totals'' column in the @command{register} and
@command{balance} reports.

@subsection Output customization

These options affect only the output, but not which postings are
used to create it:

@option{--collapse} (@option{-n}) causes transactions in a
@command{register} report with multiple postings to be collapsed
into a single, subtotaled transaction.

@option{--subtotal} (@option{-s}) causes all transactions in a
@command{register} report to be collapsed into a single, subtotaled
transaction.

@option{--by-payee} (@option{-P}) reports subtotals by payee.

@option{--comm-as-payee} (@option{-x}) changes the payee of every
posting to be the commodity used in that posting.  This can be
useful when combined with other options, such as @option{-s}.

@option{--empty} (@option{-E}) includes even empty accounts in the
@command{balance} report.

@option{--weekly} (@option{-W}) reports posting totals by the
week.  The week begins on whichever day of the week begins the month
containing that posting.  To set a specific begin date, use a
period string, such as @samp{weekly from DATE}.  @option{--monthly}
(@option{-M}) reports posting totals by month; @option{--yearly}
(@option{-Y}) reports posting totals by year.  For more complex
period, using the @option{--period} option described above.

@option{--dow} reports postings totals for each day of the week.
This is an easy way to see if weekend spending is more than on
weekdays.

@option{--sort EXPR} (@option{-S EXPR}) sorts a report by comparing
the values determined using the value expression @var{EXPR}.  For
example, using @option{-S -UT} in the balance report will sort account
balances from greatest to least, using the absolute value of the
total.  For more on how to use value expressions, see @ref{Value
expressions}.

@option{--wide} (@option{-w}) causes the default @command{register}
report to assume 132 columns instead of 80.

@option{--head} causes only the first N transactions to be printed.  This
is different from using the command-line utility @command{head}, which
would limit to the first N postings.  @option{--tail} outputs only
the last N transactions.  Both options may be used simultaneously.  If a
negative amount is given, it will invert the meaning of the flag
(instead of the first five transactions being printed, for example, it
would print all but the first five).

@option{--pager} tells @ledgerprog@ to pass its output to the given pager
program---very useful when the output is especially long.  This
behavior can be made the default by setting the @env{LEDGER_PAGER}
environment variable.

@option{--average} (@option{-A}) reports the average posting
value.

@option{--deviation} (@option{-D}) reports each posting's
deviation from the average.  It is only meaningful in the
@command{register} and @command{prices} reports.

@option{--percentage} (@option{-%}) shows account subtotals in the
@command{balance} report as percentages of the parent account.

@option{--totals} include running total information in the
@command{xml} report.

@option{--amount-data} (@option{-j}) changes the @command{register}
report so that it outputs nothing but the date and the value column,
and the latter without commodities.  This is only meaningful if the
report uses a single commodity.  This data can then be fed to other
programs, which could plot the date, analyze it, etc.

@option{--total-data} (@option{-J}) changes the @command{register}
report so that it outputs nothing but the date and totals column,
without commodities.

@option{--display EXPR} (@option{-d EXPR}) limits which postings
or accounts or actually displayed in a report.  They might still be
calculated, and be part of the running total of a register report, for
example, but they will not be displayed.  This is useful for seeing
last month's checking postings, against a running balance which
includes all posting values:

@example
ledger -d "d>=[last month]" reg checking
@end example

The output from this command is very different from the following,
whose running total includes only postings from the last month
onward:

@example
ledger -p "last month" reg checking
@end example

Which is more useful depends on what you're looking to know: the total
amount for the reporting range (@option{-p}), or simply a display
restricted to the reporting range (using @option{-d}).

@option{--date-format STR} (@option{-y STR}) changes the basic date
format used by reports.  The default uses a date like 2004/08/01,
which represents the default date format of @samp{%Y/%m/%d}.  To
change the way dates are printed in general, the easiest way is to put
@option{--date-format FORMAT} in the @ledgerprog@ initialization file
@file{~/.ledgerrc} (or the file referred to by @env{LEDGER_INIT}).

@option{--format STR} (@option{-F STR}) sets the reporting format for
whatever report ledger is about to make.  @xref{Format strings}.
There are also specific format commands for each report type:

@itemize
@item @option{--balance-format STR}
@item @option{--register-format STR}
@item @option{--print-format STR}
@item @option{--plot-amount-format STR} (-j @command{register})
@item @option{--plot-total-format STR} (-J @command{register})
@item @option{--equity-format STR}
@item @option{--prices-format STR}
@item @option{--wide-register-format STR} (-w @command{register})
@end itemize

@subsection Commodity reporting

These options affect how commodity values are displayed:

@option{--price-db FILE} sets the file that is used for recording
downloaded commodity prices.  It is always read on startup, to
determine historical prices.  Other settings can be placed in this
file manually, to prevent downloading quotes for a specific, for
example.  This is done by adding a line like the following:

@example
; Don't download quotes for the dollar, or timelog values
N $
N h
@end example

@option{--price-exp MINS} (@option{-L MINS}) sets the expected
freshness of price quotes, in minutes.  That is, if the last known
quote for any commodity is older than this value---and if
@option{--download} is being used---then the Internet will be
consulted again for a newer price.  Otherwise, the old price is still
considered to be fresh enough.

@option{--download} (@option{-Q}) causes quotes to be automagically
downloaded, as needed, by running a script named @command{getquote}
and expecting that script to return a value understood by ledger.  A
sample implementation of a @command{getquote} script, implemented in
Perl, is provided in the distribution.  Downloaded quote price are
then appended to the price database, usually specified using the
environment variable @env{LEDGER_PRICE_DB}.

There are several different ways that ledger can report the totals it
displays.  The most flexible way to adjust them is by using value
expressions, and the @option{-t} and @option{-T} options.  However,
there are also several ``default'' reports, which will satisfy most
users basic reporting needs:

@table @code
@item -O, --quantity
Reports commodity totals (this is the default)

@item -B, --basis
Reports the cost basis for all postings.

@item -V, --market
Reports the last known market value for all commodities.

@item -G --gain
Reports the net gain/loss for all commodities in the report that have
a price history.
@end table

@subsection Environment variables

Every option to ledger may be set using an environment variable.  If
an option has a long name such @option{--this-option}, setting the
environment variable @env{LEDGER_THIS_OPTION} will have the same
affect as specifying that option on the command-line.  Options on the
command-line always take precedence over environment variable
settings, however.

Note that you may also permanently specify option values by placing
option settings in the file @file{~/.ledgerrc}, for example:

@example
--cache /tmp/.mycache
--pager /bin/cat

@end example

@node Period expressions, Format strings, Options, Quick Reference
@section Period expressions

A period expression indicates a span of time, or a reporting interval,
or both.  The full syntax is:

@example
[INTERVAL] [BEGIN] [END]
@end example

The optional @var{INTERVAL} part may be any one of:

@example
every day
every week
every monthly
every quarter
every year
every N days     # N is any integer
every N weeks
every N months
every N quarters
every N years
daily
weekly
biweekly
monthly
bimonthly
quarterly
yearly
@end example

After the interval, a begin time, end time, both or neither may be
specified.  As for the begin time, it can be either of:

@example
from <SPEC>
since <SPEC>
@end example

The end time can be either of:

@example
to <SPEC>
until <SPEC>
@end example

Where @var{SPEC} can be any of:

@example
2004
2004/10
2004/10/1
10/1
october
oct
this week  # or day, month, quarter, year
next week
last week
@end example

The beginning and ending can be given at the same time, if it spans a
single period.  In that case, just use @var{SPEC} by itself.  In that
case, the period @samp{oct}, for example, will cover all the days in
october.  The possible forms are:

@example
<SPEC>
in <SPEC>
@end example

Here are a few examples of period expressions:

@example
monthly
monthly in 2004
weekly from oct
weekly from last month
from sep to oct
from 10/1 to 10/5
monthly until 2005
from apr
until nov
last oct
weekly last august
@end example

@node Format strings, Value expressions, Period expressions, Quick Reference
@section Format strings

Format strings may be used to change the output format of reports.
They are specified by passing a formatting string to the
@option{--format} (@option{-F}) option.  Within that string,
constructs are allowed which make it possible to display the various
parts of an account or posting in custom ways.

Within a format strings, a substitution is specified using a percent
character (@samp{%}).  The basic format of all substitutions is:

@example
%[-][MIN WIDTH][.MAX WIDTH]EXPR
@end example

If the optional minus sign (@samp{-}) follows the percent character,
whatever is substituted will be left justified.  The default is right
justified.  If a minimum width is given next, the substituted text
will be at least that wide, perhaps wider.  If a period and a maximum
width is given, the substituted text will never be wider than this,
and will be truncated to fit.  Here are some examples:

@example
%-P     a transaction's payee, left justified
%20P    The same, right justified, at least 20 chars wide
%.20P   The same, no more than 20 chars wide
%-.20P  Left justified, maximum twenty chars wide
@end example

The expression following the format constraints can be a single
letter, or an expression enclosed in parentheses or brackets.  The
allowable expressions are:

@table @code
@item %
Inserts a percent sign.

@item t
Inserts the results of the value expression specified by @option{-t}.
If @option{-t} was not specified, the current report style's value
expression is used.

@item T
Inserts the results of the value expression specified by @option{-T}.
If @option{-T} was not specified, the current report style's value
expression is used.

@item |
Inserts a single space.  This is useful if a width is specified, for
inserting a certain number of spaces.

@item _
Inserts a space for each level of an account's depth.  That is, if an
account has two parents, this construct will insert two spaces.  If a
minimum width is specified, that much space is inserted for each level
of depth.  Thus @samp{%5_}, for an account with four parents, will
insert twenty spaces.

@item (EXPR)
Inserts the amount resulting from the value expression given in
parentheses.  To insert five times the total value of an account, for
example, one could say @samp{%12(5*O)}.  Note: It's important to put
the five first in that expression, so that the commodity doesn't get
stripped from the total.

@item [DATEFMT]
Inserts the result of formatting a posting's date with a date
format string, exactly like those supported by @code{strftime}.  For
example: @samp{%[%Y/%m/%d %H:%M:%S]}.

@item S
Insert the pathname of the file from which the transaction's data was read.

@item B
Inserts the beginning character position of that transaction within the file.

@item b
Inserts the beginning line of that transaction within the file.

@item E
Inserts the ending character position of that transaction within the file.

@item e
Inserts the ending line of that transaction within the file.

@item D
By default, this is the same as @samp{%[%Y/%m%/d]}.  The date format
used can be changed at any time with the @option{-y} flag, however.
Using @samp{%D} gives the user more control over the way dates are
output.

@item d
This is the same as the @samp{%D} option, unless the transaction has an
effective date, in which case it prints
@samp{[ACTUAL_DATE=EFFECTIVE_DATE]}.

@item X
If a posting has been cleared, this inserts @samp{*} followed by a
space; otherwise nothing is inserted.

@item Y
This is the same as @samp{%X}, except that it only displays a state
character if all of the member postings have the same state.

@item C
Inserts the checking number for a transaction, in parentheses, followed by
a space; if none was specified, nothing is inserted.

@item P
Inserts the payee related to a posting.

@item a
Inserts the optimal short name for an account.  This is normally used
in balance reports.  It prints a parent account's name if that name
has not been printed yet, otherwise it just prints the account's name.

@item A
Inserts the full name of an account.

@item W
This is the same as @samp{%A}, except that it first displays the
posting's state @emph{if the transaction's posting states are not
all the same}, followed by the full account name.  This is offered as
a printing optimization, so that combined with @samp{%Y}, only the
minimum amount of state detail is printed.

@item o
Inserts the ``optimized'' form of a posting's amount.  This is
used by the print report.  In some cases, this inserts nothing; in
others, it inserts the posting amount and its cost.  It's use is
not recommend unless you are modifying the print report.

@item n
Inserts the note associated with a posting, preceded by two spaces
and a semi-colon, if it exists.  Thus, no none becomes an empty
string, while the note @samp{foo} is substituted as @samp{ ; foo}.

@item N
Inserts the note associated with a posting, if one exists.

@item /
The @samp{%/} construct is special.  It separates a format string
between what is printed for the first posting of a transaction, and
what is printed for all subsequent postings.  If not used, the
same format string is used for all postings.
@end table

@node Value expressions, File format, Format strings, Quick Reference
@section Value expressions

Value expressions are an expression language used by @ledgerprog@ to
calculate values used by the program for many different purposes:

@enumerate
@item
The values displayed in reports
@item
For predicates (where truth is anything non-zero), to determine which
postings are calculated (@option{-l}) or displayed (@option{-d}).
@item
For sorting criteria, to yield the sort key.
@item
In the matching criteria used by automated postings.
@end enumerate

Value expressions support most simple math and logic operators, in
addition to a set of one letter functions and variables.  A function's
argument is whatever follows it.  The following is a display predicate
that I use with the @command{balance} command:

@example
ledger -d /^Liabilities/?T<0:UT>100 balance
@end example

The effect is that account totals are displayed only if: 1) A
Liabilities account has a total less than zero; or 2) the absolute
value of the account's total exceeds 100 units of whatever commodity
contains.  If it contains multiple commodities, only one of them must
exceed 100 units.

Display predicates are also very handy with register reports, to
constrain which transactions are printed.  For example, the following
command shows only transactions from the beginning of the current month,
while still calculating the running balance based on all transactions:

@example
ledger -d "d>[this month]" register checking
@end example

This advantage to this command's complexity is that it prints the
running total in terms of all transactions in the register.  The following,
simpler command is similar, but totals only the displayed
postings:

@example
ledger -b "this month" register checking
@end example

@subsection Variables

Below are the one letter variables available in any value expression.
For the register and print commands, these variables relate to
individual postings, and sometimes the account affected by a
posting.  For the balance command, these variables relate to
accounts---often with a subtle difference in meaning.  The use of each
variable for both is specified.

@table @code
@item t
This maps to whatever the user specified with @option{-t}.  In a
register report, @option{-t} changes the value column; in a balance
report, it has no meaning by default.  If @option{-t} was not
specified, the current report style's value expression is used.

@item T
This maps to whatever the user specified with @option{-T}.  In a
register report, @option{-T} changes the totals column; in a balance
report, this is the value given for each account.  If @option{-T} was
not specified, the current report style's value expression is used.

@item m
This is always the present moment/date.
@end table

@subsubsection Posting/account details

@table @code
@item d
A posting's date, as the number of seconds past the epoch.  This
is always ``today'' for an account.

@item a
The posting's amount; the balance of an account, without
considering children.

@item b
The cost of a posting; the cost of an account, without its
children.

@item v
The market value of a posting, or an account without its children.

@item g
The net gain (market value minus cost basis), for a posting or an
account without its children.  It is the same as @samp{v-b}.

@item l
The depth (``level'') of an account.  If an account has one parent,
it's depth is one.

@item n
The index of a posting, or the count of postings affecting an
account.

@item X
1 if a posting's transaction has been cleared, 0 otherwise.

@item R
1 if a posting is not virtual, 0 otherwise.

@item Z
1 if a posting is not automated, 0 otherwise.
@end table

@subsubsection Calculated totals

@table @code
@item O
The total of all postings seen so far, or the total of an account
and all its children.

@item N
The total count of postings affecting an account and all its
children.

@item B
The total cost of all postings seen so far; the total cost of an
account and all its children.

@item V
The market value of all postings seen so far, or of an account and
all its children.

@item G
The total net gain (market value minus cost basis), for a series of
postings, or an account and its children.  It is the same as
@samp{V-B}.
@end table

@subsection Functions

The available one letter functions are:

@table @code
@item -
Negates the argument.

@item U
The absolute (unsigned) value of the argument.

@item S
Strips the commodity from the argument.

@item A
The arithmetic mean of the argument; @samp{Ax} is the same as
@samp{x/n}.

@item P
The present market value of the argument.  The syntax @samp{P(x,d)} is
supported, which yields the market value at time @samp{d}.  If no date
is given, then the current moment is used.
@end table

@subsection Operators

The binary and ternary operators, in order of precedence, are:

@enumerate
@item @samp{* /}
@item @samp{+ -}
@item @samp{! < > =}
@item @samp{& | ?:}
@end enumerate

@subsection Complex expressions

More complicated expressions are possible using:

@table @code
@item NUM
A plain integer represents a commodity-less amount.

@item @{AMOUNT@}
An amount in braces can be any kind of amount supported by ledger,
with or without a commodity.  Use this for decimal values.

@item /REGEXP/
@item W/REGEXP/
A regular expression that matches against an account's full name.  If
a posting, this will match against the account affected by the
posting.

@item //REGEXP/
@item p/REGEXP/
A regular expression that matches against a transaction's payee name.

@item ///REGEXP/
@item w/REGEXP/
A regular expression that matches against an account's base name.  If
a posting, this will match against the account affected by the
posting.

@item c/REGEXP/
A regular expression that matches against the transaction code (the text
that occurs between parentheses before the payee name).

@item e/REGEXP/
A regular expression that matches against a posting's note, or
comment field.

@item (EXPR)
A sub-expression is nested in parenthesis.  This can be useful passing
more complicated arguments to functions, or for overriding the natural
precedence order of operators.

@item [DATE]
Useful specifying a date in plain terms.  For example, you could say
@samp{[2004/06/01]}.
@end table