lnav

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_This is the source repository for **lnav**, visit [https://lnav.org](https://lnav.org) for a high level overview._

# LNAV -- The Logfile Navigator

The Logfile Navigator is a log file viewer for the terminal.  Given a
set of files/directories, **lnav** will:

- decompress as needed;
- detect their format;
- merge the files by time into a single view;
- tail the files, follow renames, find new files in directories;
- build an index of errors and warnings;
- [pretty-print JSON-lines](https://docs.lnav.org/en/latest/formats.html#json-lines).

Then, in the **lnav** TUI, you can:

- jump quickly to the previous/next error ([press `e`/`E`](https://docs.lnav.org/en/latest/hotkeys.html#spatial-navigation));
- search using regular expressions ([press `/`](https://docs.lnav.org/en/latest/hotkeys.html#spatial-navigation));
- highlight text with a regular expression ([`:highlight`](https://docs.lnav.org/en/latest/commands.html#highlight-pattern) command);
- filter messages using [regular expressions](https://docs.lnav.org/en/latest/usage.html#regular-expression-match) or [SQLite expressions](https://docs.lnav.org/en/latest/usage.html#sqlite-expression);
- pretty-print structured text ([press `P`](https://docs.lnav.org/en/latest/ui.html#pretty));
- view a histogram of messages over time ([press `i`](https://docs.lnav.org/en/latest/ui.html#hist));
- analyze messages using SQLite ([press `;`](https://docs.lnav.org/en/latest/sqlext.html))

## Screenshot

The following screenshot shows a mix of syslog and web access log
files.  Failed requests are shown in red.  Identifiers, like IP
address and PIDs are semantically highlighted.

[![Screenshot](docs/assets/images/lnav-front-page.png)](docs/assets/images/lnav-front-page.png)

## Why not **just** use `tail`/`grep`/`less`?

The standard Unix utilities are great for processing raw text lines,
however, they do not understand log messages.  Tail can watch
multiple files at a time, but it won't display messages in order by
time and you can't scroll backwards.  Grep will only find matching
lines, but won't return a full multi-line log message.  Less can only
display a single file at a time.  Also, none of t