Introduction ============ The Log File Navigator, **lnav**, is an advanced log file viewer for the terminal. It provides an :ref:`easy-to-use interface` for monitoring and analyzing your log files with little to no setup. Simply point **lnav** at your log files and it will automatically detect the :ref:`log_formats`, index their contents, and display a combined view of all log messages. You can navigate through your logs using a variety of :ref:`hotkeys`. :ref:`Commands` give you additional control over **lnav**'s behavior for doing things like applying filters, tagging messages, and more. You can then analyze your log messages using the :ref:`sql-ext`. .. figure:: lnav-intro-screen.png :align: center :alt: Screenshot of lnav showing a mix of syslog and web access_log messages. Screenshot of **lnav** viewing syslog and web access_log messages. Downloads --------- Binaries and source code for lnav can be downloaded from the `releases page `_. When building from source, follow the steps in :ref:`development`. Viewing Logs ------------ The arguments to **lnav** are the log files, directories, or URLs to be viewed. For example, to view all of the CUPS logs on your system: .. prompt:: bash lnav /var/log/cups The formats of the logs are determined automatically and indexed on-the-fly. See :ref:`log_formats` for a listing of the predefined formats and how to define your own. If no arguments are given, **lnav** will try to open the syslog file on your system: .. prompt:: bash lnav Setup ----- After starting **lnav**, you might want to set the :ref:`configuration options` mentioned below. Configuration in **lnav** is done using the :code:`:config` command. To change a configuration option, start by pressing :kbd:`:` to enter the command prompt. Then, type "config" followed by the option name and value. .. note:: Tab-completion is available for these configuration options and, in some cases, their values as well. Keymap ^^^^^^ The keymap defines the mapping from :ref:`hotkeys` to commands to execute. The default mapping is for "U.S." keyboards. The following command can be used to change the keymap: .. code-block:: lnav :config /ui/keymap The builtin keymaps are: :de: `German `_ :fr: `French `_ :sv: `Swedish `_ :uk: `United Kingdom `_ :us: `United States `_ To create or customize a keymap, consult the :ref:`keymaps` section. Theme ^^^^^ The visual styling of **lnav** can be customized using a theme. The following command can be used to the change the theme: .. code-block:: lnav :config /ui/theme The builtin themes are: `default `_, `dracula `_, `eldar `_, `grayscale `_, `monocai `_, `night-owl `_, `solarized-dark `_, and `solarized-light `_. To create or customize a theme, consult the :ref:`themes` section. Cursor Mode (v0.11.2+) ^^^^^^^^^^^^^^^^^^^^^^ The default mode for scrolling in **lnav** is to move the contents of the main view when the arrow keys are pressed. Any interactions, such as jumping to a search hit, are then focused on the top line in the view. Alternatively, you can enable "cursor" mode where there is a cursor line in the view that is moved by the arrow keys and other interactions. You can enable cursor mode with the following command: .. code-block:: lnav :config /ui/movement/mode cursor Log Formats ^^^^^^^^^^^ In order for **lnav** to understand your log files, it needs to told how to parse the log messages using a log format definition. There are many log formats builtin and **lnav** will automatically determine the best format to use. In case your log file is not recognized, consult the :ref:`log_formats` section for information on how to create a format. .. _development: Development ----------- Development of lnav is hosted on `GitHub `_. `Issues `_ should be used for bugs and feature requests. `Discussions `_ should be used for asking questions and sharing tips. Dependencies ^^^^^^^^^^^^ When compiling from source, the following dependencies are required: * `NCurses `_ * `PCRE2 `_ * `SQLite `_ * `ZLib `_ * `Bzip2 `_ * `Readline `_ * `libcurl `_ * `libarchive `_ Installation ^^^^^^^^^^^^ Check the `downloads page `_ to see if there are packages for your operating system. To compile from source, use the following commands: .. prompt:: bash ./configure make sudo make install