# hl [![Build Status][ci-img]][ci] [![Coverage Status][cov-img]][cov] [![Release][release-img]][release] [![banner](docs/assets/banner.svg)](#screenshot) High-performance log viewer and processor that transforms logs in JSON and logfmt formats into a human-readable output. Built with efficiency in mind, it enables quick parsing and analysis of large log files with minimal overhead. ## Features overview * __[Automatic Pager Integration](#automatic-usage-of-pager)__: Automatically integrates with a pager for enhanced convenience, defaulting to [less](https://greenwoodsoftware.com/less/) if available, but fully supporting any compatible pager. * __Log Streaming Mode__: Enable log streaming with the `-P` flag, which disables the pager. * __[Field-Based Filtering](#filtering-by-field-values)__: Filter log records by key/value pairs using the `-f` option, with support for hierarchical keys. * __[Level Filtering](#quick-filtering-by-log-level)__: Easily filter logs by level with the `-l` option. * __[Timestamp Range Filtering](#filtering-by-time-range)__: Filter logs by timestamp range using the `--since` and `--until` options with intuitive formats: * RFC-3339 timestamp format. * Current configured timestamp output format (via the `-t` option or environment variable). * User-friendly shortcuts like `today`, `yesterday`, `friday`, or relative offsets such as `-3h` or `-14d`. * __[Field Visibility Control](#hiding-or-revealing-selected-fields)__: Quickly hide or reveal specific fields using the `-h` option. * __Empty Field Hiding__: Automatically hide empty fields with the `-e` flag. * __Field Expansion__: Control multi-line field and message formatting with the `-x` option: * `never`: Compact single-line output with escaped newlines. * `inline`: Preserve newlines as-is in the output. * `auto`: Automatically expand fields containing multi-line content. * `always`: Expand all fields into structured multi-line format. * __[High-Speed Message Sorting](#sorting-messages-chronologically)__: Achieve lightning-fast message sorting with automatic indexing via the `-s` flag. * Performs the initial scan at approximately 2 GiB/s, enabling rapid filtering by timestamp and level without re-scanning. * Efficiently handles hundreds of local files totaling hundreds of gigabytes. * Reindexes large, growing files at speeds up to roughly 10 GiB/s by skipping unmodified blocks. * __[Live Follow Mode](#sorting-messages-chronologically-with-following-the-changes)__: Use the `-F` flag for live, timestamp-sorted message updates across multiple sources, with a preview of recent messages via the `--tail` option. * __[Complex Query Support](#performing-complex-queries)__: Construct custom queries with logical conditions (AND/OR) and additional advanced filtering options. * __Non-JSON Prefix Handling__: Process logs with non-JSON prefixes using the `--allow-prefix` flag. * __Timezone Flexibility__: Displays timestamps in UTC by default while allowing effortless timezone switching with the `-Z` option or local timezone adjustments using the `-L` flag. * __Customizability and Themes__: Fully customizable through [configuration files](#configuration-files) and environment variables, with support for easy [theme switching](#selecting-current-theme) and custom [themes](#custom-themes). ## Performance comparison chart ### Performance comparison with [humanlog](https://github.com/humanlogio/humanlog), [hlogf](https://github.com/ssgreg/hlogf) and [fblog](https://github.com/brocode/fblog) on a 2.3 GiB log file ![performance chart](docs/assets/performance-chart.svg) * See [performance](#performance) section for more details. ## Installation options ### macOS * Install using [homebrew](https://brew.sh) on macOS ```sh brew install hl ```
Other options * Download and extract using `curl` and `tar` on macOS ```sh curl -sSfL https://github.com/pamburus/hl/releases/latest/download/hl-macos.tar.gz | tar xz ``` * Install using [cargo](https://www.rust-lang.org/tools/install) ```sh cargo install --locked --git https://github.com/pamburus/hl.git ``` * Download latest release from [download page](https://github.com/pamburus/hl/releases/latest)
### Linux * Download and extract using `curl` and `tar` on Linux (x86_64) ```sh curl -sSfL https://github.com/pamburus/hl/releases/latest/download/hl-linux-x86_64-musl.tar.gz | tar xz ``` * Install [hl package](https://archlinux.org/packages/extra/x86_64/hl/) from Arch Linux extra repository ```sh pacman -S hl ```
Other options * Download and extract using `curl` and `tar` on Linux (arm64/aarch64) ```sh curl -sSfL https://github.com/pamburus/hl/releases/latest/download/hl-linux-arm64-musl.tar.gz | tar xz ``` * Install using [cargo](https://www.rust-lang.org/tools/install) ```sh cargo install --locked --git https://github.com/pamburus/hl.git ```
### Windows * Install from [Scoop](https://scoop.sh) ```sh scoop bucket add pamburus https://github.com/pamburus/scoop-bucket.git scoop install hl ``` > [!TIP] > It is recommended to use [Windows Terminal](https://aka.ms/terminal) for better experience. > [!TIP] > To make mouse scrolling work in the [less](https://www.greenwoodsoftware.com/less/) pager, set the `LESS` environment variable to `-R --mouse`. > [!IMPORTANT] > Currently, `hl` does not provide a built-in pager and relies on external pagers such as [less](https://www.greenwoodsoftware.com/less/). > However, the [build for Windows]([https://github.com/jftuga/less-Windows]) referenced on the original [download page](https://www.greenwoodsoftware.com/less/download.html) and distributed in the [WinGet](https://winget.run/pkg/jftuga/less) package manager does not work as expected. > The authors state that they have not tested or verified this build and suggest that you use it at your own risk. > Unfortunately, this build breaks some ANSI escape sequences and does not work properly with `hl` and many other programs that use ANSI escape sequences for colors and styles. > It is recommended to install [less](https://www.greenwoodsoftware.com/less/) from the [Scoop](https://scoop.sh) or [Chocolatey](https://chocolatey.org/) package manager. > If you are using [Scoop](https://scoop.sh) and install `hl` by running `scoop install hl`, it already installs [less](https://www.greenwoodsoftware.com/less/) automatically as a dependency. Just make sure you do not have any other conflicting installations by running `where less` in cmd or `Get-Command less` in powershell. * Download latest release from [download page](https://github.com/pamburus/hl/releases/latest)
Other options * Install using [cargo](https://www.rust-lang.org/tools/install) ```sh cargo install --locked --git https://github.com/pamburus/hl.git ```
### NixOS * Run using [nix](https://nixos.org/download/) ```sh nix run github:pamburus/hl ``` or binary package ```sh nix run github:pamburus/hl#bin ``` or install with [nix profile](https://nix.dev/manual/nix/2.31/command-ref/new-cli/nix3-profile-add): ```sh nix profile add github:pamburus/hl ``` or binary package ```sh nix profile add github:pamburus/hl#bin ``` * Install the package from source using [nix-flakes](https://wiki.nixos.org/wiki/Flakes)
Example how to update nix configuration ```nix { inputs = { nixpkgs.url = "github:NixOS/nixpkgs/nixos-25.05"; hl.url = "github:pamburus/hl"; }; outputs = {nixpkgs, hl, ...}: let system = "x86_64-linux"; in { # this is just an example! nixosConfigurations.yourHost = nixpkgs.lib.nixosSystem { inherit system; modules = [ ({...}: { environment.systemPackages = [ hl.packages.${system} ]; }) ]; }; }; } ```
* Install the package with pre-built binaries using [nix-flakes](https://wiki.nixos.org/wiki/Flakes)
Example how to update nix configuration ```nix { inputs = { nixpkgs.url = "github:NixOS/nixpkgs/nixos-25.05"; hl.url = "github:pamburus/hl"; }; outputs = {nixpkgs, hl, ...}: let system = "x86_64-linux"; in { # this is just an example! nixosConfigurations.yourHost = nixpkgs.lib.nixosSystem { inherit system; modules = [ ({...}: { environment.systemPackages = [ hl.packages.${system}.bin ]; }) ]; }; }; } ```
## Examples ### Screenshot

screenshot

See other [screenshots](https://github.com/pamburus/hl-extra/blob/37b444fcd812563963631071af581445851aa86e/screenshot/README.md#current-mode) ## Features and usage ### Concatenation of multiple log files * Concatenate all log files Command ```sh hl *.log ``` Concatenates and displays all `*.log` files found in the current directory. ### Support for compressed (bzip2, gzip, xz, zstd) log files * Concatenate all log files including compressed log files Command ```sh hl $(ls -tr /var/log/example/*.{log,log.gz,log.zst,s}) ``` Concatenates and displays all `*.log`, `*.log.gz`, `*.log.zst` and `*.s` (will detect compression) files found in `/var/log/example/`. ### Automatic usage of pager * Use the default pager with the default parameters Command ```sh hl example.log ``` Automatically opens `less` pager with the default parameters. * Override options for default pager Command ```sh LESS=-SR hl example.log ``` Opens `less` pager with disabled line wrapping. * Use custom pager Command ```sh PAGER="most -w" hl example.log ``` Opens `most` pager with `-w` option. ### Quick filtering by log level * Errors only Command ```sh hl -l e ``` Displays only error log level messages. * Errors and warnings Command ```sh hl -l w ``` Displays only warning and error log level messages. * Errors, warnings and informational Command ```sh hl -l i ``` Displays all log messages except debug level messages. ### Using live log streaming * Command ```sh tail -f example.log | hl -P ``` Tracks changes in the example.log file and displays them immediately. Flag `-P` disables automatic using of pager in this case. ### Filtering by field values * Command ```sh hl example.log --filter component=tsdb ``` Displays only messages where the `component` field has the value `tsdb`. * Command ```sh hl example.log -f component!=tsdb -f component!=uninteresting ``` Displays only messages where the `component` field exists and has a value other than `tsdb` or `uninteresting`. * Command ```sh hl example.log -f provider~=string ``` Displays only messages where the `provider` field contains the `string` sub-string. * Command ```sh hl example.log -f 'provider!~=string' ``` Displays only messages where the `provider` field exists and does not contain the `string` sub-string. * Command ```sh hl example.log -f 'request.method?!=GET' ``` Displays only messages where the `request.method` field does not exist or exists and is not equal to `GET`. In JSON messages, this also matches composite fields, e.g., `{"request":{"method":"POST"}}`. * Command ```sh hl example.log -f 'span.[].name=sp0001' ``` Displays only messages where the `span` field is an array that contains an object with a `name` field equal to `sp0001`. * Command ```sh hl example.log -f 'span.[1].name=sp0001' ``` Displays only messages where the `span` field is an array with at least two elements, and the element at index 1 (i.e., the second element) is an object with a `name` field equal to `sp0001`. ### Performing complex queries * Command ```sh hl my-service.log --query 'level > info or status-code >= 400 or duration > 0.5' ``` Displays messages that either have a level higher than info (i.e. warning or error) or have a status code field with a numeric value >= 400 or a duration field with a numeric value >= 0.5. * Command ```sh hl my-service.log -q '(request in (95c72499d9ec, 9697f7aa134f, bc3451d0ad60)) or (method != GET)' ``` Displays all messages that have the 'request' field with one of these values, or the 'method' field with a value other than 'GET'. * Command ```sh hl my-service.log -q '.price?=3' ``` Displays messages where the `price` field equals `3` OR the `price` field is absent. The `?` modifier after a field name includes records that don't have that field. Without the `?` modifier, filtering on a missing field will skip the record. * Command ```sh hl my-service.log -q '.status?!=error' ``` Displays messages where the `status` field is not equal to `error` OR the `status` field is absent. This is useful to include records that may not have a status field at all. * Command ```sh hl my-service.log -q 'exists(.price)' ``` Displays only messages that have the `price` field, regardless of its value. The `exists()` operator tests for field presence without any value comparison. * Command ```sh hl my-service.log -q 'exists(msg) and msg~=warning' ``` Displays messages that have a `msg` field that exists AND contains the substring `warning`. This combines field existence checking with value matching. * Command ```sh hl my-service.log -q 'not exists(.internal)' ``` Displays messages that do NOT have an `internal` field, effectively filtering out records with that field. * Complete set of supported operators * Logical operators * Logical conjunction - `and`, `&&` * Logical disjunction - `or`, `||` * Logical negation - `not`, `!` * Comparison operators * Equal - `eq`, `=` * Not equal - `ne`, `!=` * Greater than - `gt`, `>` * Greater or equal - `ge`, `>=` * Less than - `lt`, `<` * Less or equal - `le`, `<=` * String matching operators * Sub-string check - (`contain`, `~=`), (`not contain`, `!~=`) * Wildcard match - (`like`), (`not like`) * Wildcard characters are: `*` for zero or more characters and `?` for a single character * Regular expression match - (`match`, `~~=`), (`not match`, `!~~=`) * Operators with sets * Test if a value is one of the values in a set - `in (v1, v2)`, `not in (v1, v2)` * Test if a value is one of the values in a set loaded from a file - `in @filename`, `not in @filename`, assuming that each element is a line in the file, which can be either a simple string or a JSON string * Test if a value is one of the values in a set loaded from stdin - `in @-`, `not in @-` * Field existence operators * Test if a field exists - `exists(.field)` or `exist(.field)` (both forms are supported) * Notes * __Include Absent Modifier (`?`)__: When appending `?` to a field name (e.g., `.field?=value`), the filter will match both: * Records where the field exists and matches the condition * Records where the field is absent (does not exist) This is useful in logfmt or similar formats where fields may be optional. Without the `?` modifier, records with a non-existent field are excluded from the results. * Special field names that are reserved for filtering by predefined fields regardless of the actual source field names used to load the corresponding value: `level`, `message`, `caller` and `logger`. * To address a source field with one of these names instead of predefined fields, add a period before its name, i.e., `.level` will perform a match against the "level" source field. * To address a source field by its exact name, use a JSON-formatted string, i.e. `-q '".level" = info'`. * To specify special characters in field values, also use a JSON-formatted string, i.e. ```sh hl my-service.log -q 'message contain "Error:\nSomething unexpected happened"' ``` ### Filtering by time range * Command ```sh hl example.log --since 'Jun 19 11:22:33' --until yesterday ``` Displays only messages that occurred after Jun 19 11:22:33 UTC of the current year (or the previous year if the current date is less than Jun 19 11:22:33) and before yesterday midnight. * Command ```sh hl example.log --since -3d ``` Displays only messages from the past 72 hours. * Command ```sh hl example.log --until '2021-06-01 18:00:00' --local ``` Displays only messages that occurred before 6 PM local time on June 1, 2021, and shows timestamps in local time. ### Hiding or revealing selected fields * Command ```sh hl example.log --hide provider ``` Hides field `provider`. * Command ```sh hl example.log --hide '*' --hide '!provider' ``` Hides all fields except `provider`. * Command ```sh hl example.log -h headers -h body -h '!headers.content-type' ``` Hides fields `headers` and `body` but shows a single sub-field `content-type` inside field `headers`. ### Sorting messages chronologically * Command ```sh hl -s *.log ``` Displays log messages from all log files in the current directory sorted in chronological order. ### Sorting messages chronologically with following the changes * Command ```sh hl --sync-interval-ms 500 -F <(kubectl logs -l app=my-app-1 -f) <(kubectl logs -l app=my-app-2 -f) ``` Runs without a pager in follow mode by merging messages from the outputs of these 2 commands and sorting them chronologically within a custom 500ms interval. * Command ```sh hl -F --tail 100 app1.log app2.log app3.log ``` Runs without a pager in follow mode, following the changes in three log files in the current directory and sorting them chronologically at a default interval of 100ms. Preloads 100 lines from the end of each file before filtering. ### Configuration files * Configuration files are automatically loaded if found in predefined platform-specific locations. | OS | System-Wide Location | User Profile Location | | ------- | ---------------------------------------- | ------------------------------------------------------- | | macOS | /etc/hl/config.{yaml,toml,json} | ~/.config/hl/config.{yaml,toml,json} | | Linux | /etc/hl/config.{yaml,toml,json} | ~/.config/hl/config.{yaml,toml,json} | | Windows | %PROGRAMDATA%\hl\config.{yaml,toml,json} | %USERPROFILE%\AppData\Roaming\hl\config.{yaml,toml,json} | * The path to the configuration file can be overridden using the `HL_CONFIG` environment variable or the `--config` command-line option. The order in which the configuration files are searched and loaded is as follows: 1. __The system-wide location.__ 2. __The user profile location.__ 3. __The location specified by the `HL_CONFIG` environment variable__ (unless the `--config` option is used). 4. __The locations specified by the `--config` option__ (can be specified multiple times). If a configuration file is found in multiple locations, the file in each subsequent location overrides only the parameters it contains. If `HL_CONFIG` or `--config` specifies `-` or an empty string, all default locations and any locations specified by previous `--config` options are discarded. The search for the configuration file locations starts over. To disable loading of configuration files and use the built-in defaults, `--config -` can be used. * All parameters in the configuration file are optional and can be omitted. In this case, default values are used. #### Default configuration file * [config.toml](etc/defaults/config.toml) ### Environment variables * Many parameters that are defined in command line arguments and configuration files can also be specified by environment variables. #### Precedence of configuration sources (from lowest priority to highest priority) * Configuration file * Environment variables * Command-line arguments #### Environment variables examples * `HL_TIME_FORMAT='%y-%m-%d %T.%3N'` overrides the time format specified in the configuration file. * `HL_TIME_ZONE=Europe/Berlin` overrides the time zone specified in the configuration file. * `HL_CONCURRENCY=4` overrides the concurrency limit specified in the configuration file. * `HL_PAGING=never` specifies the default value for the paging option, but it can be overridden by command line arguments. ### Themes #### Stock themes * [themes](etc/defaults/themes/) #### Selecting current theme * Using `theme` value in the configuration file. * Using environment variable, i.e. `HL_THEME=classic`, overrides the value specified in configuration file. * Using command-line argument, i.e. `--theme classic`, overrides all other values. #### Theme overlays Theme overlays allow you to apply multiple theme modifications on top of your base theme and main configured theme, enabling compositional theming. Overlays are merged in order: `@base` → configured theme → overlays (in list order). * Configure overlays in your configuration file using the `theme-overlays` setting: ```yaml theme: "uni" theme-overlays: ["@accent-italic"] ``` * Overlays are regular theme files that can customize specific aspects without replacing the entire theme * Overlays are applied in the specified order, allowing fine-grained control over theme composition * Empty array `[]` or omitting `theme-overlays` means no overlays are applied * Overlay themes are typically tagged with `overlay` and excluded from default theme listings (use `--list-themes=overlay` to view them) #### Selecting themes with preview To select themes with preview [fzf](https://github.com/junegunn/fzf) tool can be used like this: ```bash hl --list-themes | fzf --color='bg+:23,gutter:-1,pointer:210' --highlight-line --preview-window 'right,border-left,88%,<142(up,88%,border-bottom)' --preview="hl -t '%b %d %T' --input-info minimal -c --theme {} sample/*.log" ``` #### Custom themes For complete theme configuration reference, see __[Theme Configuration Guide](docs/theme/theme.md)__. * Custom themes are automatically loaded when found in a predefined platform-specific location. | OS | Location | | ------- | -------------------------------------------------------------------- | | macOS | ~/.config/hl/themes/*.{yaml,yml,toml,json} | | Linux | ~/.config/hl/themes/*.{yaml,yml,toml,json} | | Windows | %USERPROFILE%\AppData\Roaming\hl\themes\*.{yaml,yml,toml,json} | * __Structure__ * `version` (required): Must be `"1.0"` * `tags` (optional): Theme classification and filtering * Classification tags: `dark`, `light`, `16color`, `256color`, `truecolor` * Special tags: `base` (foundation themes, excluded from default listings), `overlay` (composition themes, excluded from default listings) * Use `--list-themes=base` or `--list-themes=overlay` to show themes with these tags * Theme names starting with `@` (e.g., `@base`, `@accent-italic`) are a naming convention; filtering is based on tags, not name prefixes * `styles` (optional): Reusable role-based styles that can inherit from each other * `elements` (optional): Visual styles for specific log elements * `levels` (optional): Per-level overrides for elements * `indicators` (optional): Sync indicator styling for `--follow` mode * __Example__ ```toml version = "1.0" tags = ["dark", "256color"] # Reusable styles with inheritance [styles] primary = { modes = ["-faint"] } secondary = { style = "primary", modes = ["faint"] } warning = { style = "primary", foreground = "yellow" } error = { style = "primary", foreground = "bright-red" } # Element-specific styles can reference roles [elements] message = { style = "primary", modes = ["bold"] } time = { style = "secondary" } level-inner = { style = "primary" } # Level-specific overrides [levels.warning] level-inner = { style = ["primary", "warning"] } message = { style = ["primary", "warning"] } [levels.error] level-inner = { style = ["primary", "error"] } message = { style = ["primary", "error"] } ``` * __Roles__ (predefined): `default`, `primary`, `secondary`, `strong`, `muted`, `accent`, `accent-secondary`, `message`, `syntax`, `status`, `key`, `value`, `level`, `trace`, `debug`, `info`, `warning`, `error` * __Elements__ (predefined): `input`, `input-number`, `input-number-inner`, `input-name`, `input-name-inner`, `time`, `level`, `level-inner`, `logger`, `logger-inner`, `caller`, `caller-inner`, `message`, `message-delimiter`, `field`, `key`, `array`, `object`, `string`, `number`, `boolean`, `boolean-true`, `boolean-false`, `null`, `ellipsis` * __Mode operations__: * `+mode` or `mode`: Add mode (e.g., `["+bold"]` or `["bold"]`) * `-mode`: Remove inherited mode (e.g., `["-faint"]`) * Last occurrence wins for conflicts (e.g., `["+bold", "-bold"]` removes bold) * __Inheritance chain__: `@base` theme → user theme's styles → element's `style` field → element's explicit properties * All themes inherit from built-in `@base` theme * Styles can reference other styles via `style` field * Elements can reference styles via `style` field * Explicit properties override inherited ones * __Color format__: * Keyword `default` for terminal default color * ASCII basic color names: `black`, `red`, `green`, `yellow`, `blue`, `magenta`, `cyan`, `white`, `bright-black`, `bright-red`, `bright-green`, `bright-yellow`, `bright-blue`, `bright-magenta`, `bright-cyan`, `bright-white` * 256-color palette code: `0` to `255` * RGB hex format: `#RRGGBB` (e.g., `#FFFF00` for bright yellow) * __Modes__: `bold`, `faint`, `italic`, `underline`, `slow-blink`, `rapid-blink`, `reverse`, `conceal`, `crossed-out` ### Used terminal color schemes #### iTerm2 * [One Dark Neo](https://gist.github.com/pamburus/0ad130f2af9ab03a97f2a9f7b4f18c68/746ca7103726d43b767f2111799d3cb5ec08adbb) * Built-in "Light Background" color scheme #### Alacritty * [One Dark Neo](https://gist.github.com/pamburus/e27ebf60aa17d126f5c879f06112edd6/a1e66d34a65b883f1cb8ec28820cc0c53233e3aa#file-alacritty-yml-L904) * Note: It is recommended to use `draw_bold_text_with_bright_colors: true` setting * [Light](https://gist.github.com/pamburus/e27ebf60aa17d126f5c879f06112edd6/a1e66d34a65b883f1cb8ec28820cc0c53233e3aa#file-alacritty-yml-L875) * Note: It is recommended to use `draw_bold_text_with_bright_colors: false` setting ### Complete set of options and flags ```text JSON and logfmt log converter to human readable representation Usage: hl [OPTIONS] [FILE]... Arguments: [FILE]... Files to process Options: --config Configuration file path [env: HL_CONFIG=] -s, --sort Sort entries chronologically -F, --follow Follow input streams and sort entries chronologically within time frame set by --sync-interval-ms option --tail Number of last entries to preload from each file in --follow mode [default: 10] --sync-interval-ms Synchronization interval for live streaming mode enabled by --follow option [default: 100] --paging Control pager usage (HL_PAGER or PAGER) [env: HL_PAGING=] [default: auto] [possible values: auto, always, never] -P Handful alias for --paging=never, overrides --paging option --help[=] Print help [possible values: short, long] -V, --version Print version Filtering Options: -l, --level Display entries with level >= [env: HL_LEVEL=] --since