hl

Log viewer which translates JSON logs into pretty human-readable representation. It is a faster alternative to humanlog and hlogf with several additional features.

Installation options

• Download latest release from download page

• Download and extract using curl and tar on Linux

  curl -sSfL https://github.com/pamburus/hl/releases/latest/download/hl-linux.tar.gz | tar xz
  

• Download and extract using curl and tar on macOS

  curl -sSfL https://github.com/pamburus/hl/releases/latest/download/hl-macos.tar.gz | tar xz
  

Examples

Screenshot

Features and usage

Concatenation of multiple log files

• Concatenate all log files

  Command

  $ hl $(ls -tr /var/log/example/*.log)
  

  Concatenates and humanizes all *.log files found in /var/log/example/.

Support for gzipped log files

• Concatenate all log files including gzipped log files

  Command

  $ hl $(ls -tr /var/log/example/*.{log,log.gz})
  

  Concatenates and humanizes all *.log and *.log.gz files found in /var/log/example/.

Automatic usage of pager

• Use default pager with default parameters

  Command

  $ hl example.log
  

  Automatically opens less pager with default parameters.

• Override options for default pager

  Command

  $ LESS=-SR hl example.log
  

  Opens less pager with disabled line wrapping.

• Use custom pager

  Command

  $ PAGER=bat hl example.log
  

  Opens bat pager.

Quick filtering by log level

• Errors only

  Command

  $ hl -l e
  

  Shows only messages with error log level.

• Errors and warnings

  Command

  $ hl -l w
  

  Shows only messages with warning and error log level.

• Errors, warnings and informational

  Command

  $ hl -l i
  

  Shows all log messages except debug level messages.

Using live log streaming

• Command

  $ tail -f example.log | hl -P
  

  Follows changes in example.log file and displays them immediately. Flag -P disables automatic using of pager in this case.

Filtering by field values

• Command

  $ hl example.log -f component=tsdb
  

  Shows only messages with field component having value tsdb.

• Command

  $ hl example.log -f component!=tsdb -f component!=uninteresting
  

  Shows only messages with field component having value other than tsdb or uninteresting.

• Command

  $ hl example.log -f provider~=string
  

  Shows only messages with field provider containing sub-string string.

Filtering by time range

• Command

  $ hl example.log --since 'Jun 19 11:22:33' --until yesterday
  

  Shows only messages occurred after Jun 19 11:22:33 UTC of the current year (or of the previous one if current date is less than Jun 19 11:22:33) and until yesterday midnight.

• Command

  $ hl example.log --since -3d
  

  Shows only messages for the last 72 hours.

• Command

  $ hl example.log --until '2021-06-01 18:00:00' --local
  

  Shows only messages occurred before 6 PM on 1st Jun 2021 in local time as well as show timestamps in local time.

Hiding or showing selected fields

• Command

  $ hl example.log --hide provider
  

  Hides field provider.

• Command

  $ hl example.log --show provider
  

  Hides all fields except provider.

• Command

  $ 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.

Configuration files

• Configuration file is loaded automatically if found at predefined platform-specific location.

  OS	Location
  macOS	~/.config/hl/config.yaml
  Linux	~/.config/hl/config.yaml
  Windows	%USERPROFILE%\AppData\Roaming\hl\config.yaml

• Any parameters in the configuration file are optional and may be omitted. In this case default values will be used.

Default configuration file

• config.yaml

Envrionment variables

• Many parameters which are defined in command-line arguments and configuration files may be specified by envrionment variables also.

Precedence of configuraton sources

• Configuration file
• Environment variables
• Command-line arguments

Examples

• HL_TIME_FORMAT='%y-%m-%d %T.%3N' overrides time format specified in configuration file.
• HL_TIME_ZONE=Europe/Moscow overrides time zone specified in configuration file.
• HL_CONCURRENCY=4 overrides concurrency limit specified in configuration file.
• HL_PAGING=never specified default value for paging option but it may be overriden by command-line arguments.

Themes

Stock themes

• 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.

Custom themes

• Custom themes are loaded automatically if found at predefined platform-specific location.

  OS	Location
  macOS	~/.config/hl/themes/*.yaml
  Linux	~/.config/hl/themes/*.yaml
  Windows	%USERPROFILE%\AppData\Roaming\hl\themes*.yaml

• Format description

  • Section elements contains styles for predefined elements.
  • Section levels contains optional overrides for styles defined in elements sections per logging level, which are [debug, info, warning, error].
  • Each element style contains optional background, foreground and modes parameters.
  • Example

    elements:
        <element>:
            foreground: <color>
            background: <color>
            modes: [<mode>, <mode>, ...]
    levels:
        <level>:
            <element>:
                foreground: <color>
                background: <color>
                modes: [<mode>, <mode>, ...]
  • Color format is one of
    • Keyword default specifies default color defined by the terminal.
    • ASCII basic color name, one of
      • 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, from 0 to 255.
    • RGB color in hex web color format, i.e. #FFFF00 for bright yellow color.
  • Modes is a list of additional styles, each of them is one of
    • bold
    • faint
    • italic
    • underline
    • slow-blink
    • rapid-blink
    • reverse
    • conseal
    • crossed-out

Complete set of options and flags

hl 0.11.0
JSON log converter to human readable representation

USAGE:
    hl [OPTIONS] [--] [FILE]...

ARGS:
    <FILE>...    Files to process

OPTIONS:
        --buffer-size <BUFFER_SIZE>                          Buffer size [env: HL_BUFFER_SIZE=] [default: "2 MiB"]
    -c                                                       Handful alias for --color=always, overrides --color option
    -C, --concurrency <CONCURRENCY>                          Number of processing threads [env: HL_CONCURRENCY=]
        --color <COLOR>                                      Color output options [env: HL_COLOR=] [default: auto] [possible values: auto, always, never]
    -e, --hide-empty-fields                                  Hide empty fields, applies for null, string, object and array fields only [env: HL_HIDE_EMPTY_FIELDS=]
    -E, --show-empty-fields                                  Show empty fields, overrides --hide-empty-fields option [env: HL_SHOW_EMPTY_FIELDS=]
    -f, --filter <FILTER>                                    Filtering by field values in one of forms [<key>=<value>, <key>~=<value>, <key>~~=<value>, <key>!=<value>, <key>!~=<value>, <key>!~~=<value>] where ~ denotes substring match and ~~ denotes regular expression match
    -h, --hide <HIDE>                                        Hide fields with the specified keys
    -H, --show <SHOW>                                        Hide all fields except fields with the specified keys
        --help                                               Print help information
        --interrupt-ignore-count <INTERRUPT_IGNORE_COUNT>    Number of interrupts to ignore, i.e. Ctrl-C (SIGINT) [env: HL_INTERRUPT_IGNORE_COUNT=] [default: 3]
    -l, --level <LEVEL>                                      Filtering by level [env: HL_LEVEL=] [possible values: error, warning, info, debug]
    -L, --local                                              Use local time zone, overrides --time-zone option
        --list-themes                                        List available themes and exit
        --max-message-size <MAX_MESSAGE_SIZE>                Maximum message size [env: HL_MAX_MESSAGE_SIZE=] [default: "64 MiB"]
    -P                                                       Handful alias for --paging=never, overrides --paging option
        --paging <PAGING>                                    Output paging options [env: HL_PAGING=] [default: auto] [possible values: auto, always, never]
    -r, --raw-fields                                         Disable unescaping and prettifying of field values
        --since <SINCE>                                      Filtering by timestamp >= the value (--time-zone and --local options are honored)
    -t, --time-format <TIME_FORMAT>                          Time format, see https://man7.org/linux/man-pages/man1/date.1.html [env: HL_TIME_FORMAT=] [default: "%y-%m-%d %T.%3N"]
        --theme <THEME>                                      Color theme [env: HL_THEME=] [default: one-dark-green]
    -u, --unhide <UNHIDE>                                    Unhide fields with the specified keys
        --until <UNTIL>                                      Filtering by timestamp <= the value (--time-zone and --local options are honored)
    -V, --version                                            Print version information
    -Z, --time-zone <TIME_ZONE>                              Time zone name, see column "TZ database name" at https://en.wikipedia.org/wiki/List_of_tz_database_time_zones [env: HL_TIME_ZONE=] [default: UTC]

Performance

• MacBook Pro (16-inch, 2019)
  • CPU - 2,4 GHz 8-Core Intel Core i9
  • OS - macOS 10.15.6
  • Data - ~1GiB log file, 4.150.000 lines
    • hl v0.6.8 ~ 1 second

      $ time hl prom-m2.log -c >/dev/null
      hl prom-m2.log -c > /dev/null  12.41s user 0.64s system 1430% cpu 0.912 total
      
    • hlogf v1.4.1 ~ 10 seconds

      $ time hlogf prom-m2.log --color= >/dev/null
      hlogf prom-m2.log --color= > /dev/null  9.91s user 1.22s system 101% cpu 10.970 total
      
    • humanlog v0.4.1 ~ 60 seconds

      $ time humanlog <prom-m2.log >/dev/null
      humanlog> reading stdin...
      humanlog < prom-m2.log > /dev/null  58.55s user 4.89s system 107% cpu 58.931 total
      
    

Future features

• Optional sorting of log messages by timestamp