FSQL - File System Query Language

FSQL is a tool for performing queries on the local file system with syntax similar to SQL.

Usage

FSQL will always launch as a REPL.
Having a single query provided from the command line is not viable, as there are many aspects of the language that may conflict with the shell's syntax (that's at least for bash). Workarounds might be doable, but would be too complex to implement and to understand when writing queries.

Basic select clause

The supported selections are:
name: file name.
date: file modification date.
size: file size (bytes).

select name from path/dir

Multiple selections

The columns will be delimited by a single tab character.
The order of selections is respected.

select name, date from path/to/dir

Recursive query

Will traverse the directory recursively.

select name recursive from path/to/dir

Join clause

The supported join types are: inner, left, right, outer (left + right), full.

select name from path/to/dir inner join path/to/dir2 on date

Where clause

FSQL supports simple predicates.
A predicate is a logical expression that dictates whether a file or directory will be included in the final result.

Selection

A selection in an expression will represent the respective information from the file.
The supported selections are: name, date, size.

Literals

There are 4 types of literals: string, date, size, regex.
A string literal may contain any characters.
A date literal must be a valid YYYY-MM-DD date.
A size literal must be a valid integer.
A regex literal must be a valid POSIX extended regular expression.

Any literal may or not be enclosed in double quotes. Escape characters are only allowed in quoted literals.
There are two special escape sequences: \" and \\, which evaluate to " and \ respectively.
Any other escape sequence is kept as is.
This is specially relevant for regex literals. Example: "a\<b\"c.d" is equivalent to the regex a\<b"c.d

Operators

Types

FSQL features a type checker for expressions.
Logical operators must have both operands of boolean type.
Relational operators must have operands of the same type, and a selection operand will dictate the type, defaulting to string.
The regex match operator must have a left operand of type string, and a right operand must be a regex literal.
When used with the regex match operator, the selections date and size are converted to string.

Examples

select date, name from path/to/dir where name == file && date >= 2015-12-30
select size, name from path/to/dir where size > 20000
select date, size, name from path/to/dir where name =~ .*test-[1-9]
select date, size, name from path/to/dir where name =~ "file-with-literal-plus-\+-sign\.txt"

Installation

Binary release

FSQL comes as a single executable file, that can be downloaded from the releases page.

Build from source

FSQL uses Stack: a modern, cross-platform build tool for Haskell code.
To build FSQL, you must have Stack installed.
With just 3 commands, it will download the compiler, build all dependencies and generate the final executable:

$ stack setup
$ stack build
$ stack install

License

Copyright © 2015-2018 gahag.
All rights reserved.

This software may be modified and distributed under the terms of the BSD license. See the LICENSE file for details.