Query language

--where filters the records acted on by read, update, and delete. It is a small expression language, not SQL: there are no joins, no sub-queries, no parentheses, and no aggregations. Everything is a boolean expression over the columns of a single GTFS file.

Grammar

expression := filter | filter " OR " expression
filter     := term | term " AND " filter
term       := field operator value

operator   := "=" | "!=" | ">" | ">=" | "<" | "<=" | " LIKE "

AND binds tighter than OR. There is no way to override precedence — parentheses are not supported.

Operators

Operator	Meaning	Example
`=`	Equal	`stop_id=S01`
`!=`	Not equal	`route_type!=3`
`>`	Greater than (string-compared)	`stop_sequence>10`
`>=`	Greater or equal	`arrival_time>=06:00:00`
`<`	Less than	`date<20260101`
`<=`	Less or equal	`route_type<=4`
`LIKE`	SQL-style pattern match	`stop_name LIKE Gare%`

Comparison operators perform a plain string comparison. For numeric fields (like stop_sequence or route_type) this matches the intuitive order as long as values are zero-padded or unsigned; check your data before using < / > on free-form fields.

`LIKE` patterns

LIKE matches against a pattern where:

% stands for any sequence of characters (including empty).
_ stands for exactly one character.

Pattern	Matches
`Gare%`	`Gare Centrale`, `Gare du Nord`, `Gare`
`%Nord`	`Gare du Nord`, `Nord`
`%bus%`	Any value containing `bus`
`stop___`	`stop001`, `stopABC` — exactly 4+3 = 7 chars

Whitespace

Whitespace around operators is optional and does not change meaning:

stop_id=S01
stop_id = S01
stop_id   =   S01

Backtick-quoted values

When a value contains AND, OR, or whitespace that could be mistaken for a keyword, wrap it in backticks:

stop_name=`Gare du Nord AND Est`
route_long_name=`Express 747 OR 748`

Inside backticks, the content is taken verbatim. Backticks are not required for simple values.

Combining expressions

AND and OR let you compose filters. AND takes higher precedence, so

a=1 AND b=2 OR c=3

parses as (a=1 AND b=2) OR c=3.

Since parentheses are not supported, express a=1 AND (b=2 OR c=3) by splitting the work across commands or by narrowing it to the equivalent two-branch OR of ANDs:

a=1 AND b=2 OR a=1 AND c=3

Examples

Single-field filters

gapline read stops --where "stop_id=S01"
gapline read routes --where "route_type!=3"

Range on a numeric-looking field

gapline read stop-times --where "stop_sequence>10 AND stop_sequence<20"

Pattern match

gapline read stops --where "stop_name LIKE Gare%"
gapline read stops --where "stop_name LIKE %Nord"

Combining with OR

gapline read routes --where "route_type=3 OR route_type=1"

A value with a reserved keyword

gapline read stops --where 'stop_name=`Gare du Nord AND Est`'

Single quotes around the whole expression (in the shell) protect the backticks from your shell’s own history-expansion or command-substitution rules.

Errors

Common parser errors and what they mean:

Error	Cause
`invalid expression: ''`	`--where ""`. Pass an expression or drop the flag.
`unexpected logical operator without expressions`	`AND …`, `… OR`, or a dangling `… AND AND …`.
`empty field name`	`=value`. The left side of an operator is missing.
`empty value for field 'stop_id'`	`stop_id=`. The right side of an operator is missing.
`unknown operator in '…'`	Typo like `stop_id == S01` or `stop_id LIKES Gare%`.
`unknown field 'stop_naem'`	Field name is not a column of the target file. The error lists valid names.