lnav

advanced log file viewer that leverages semantic information from log files

TLDR

View log files

$ lnav path/to/log

View logs in a directory

$ lnav /var/log/

View remote log files via SSH

$ lnav ssh user@host:/var/log/syslog

Validate log format configuration

$ lnav -C path/to/log

Include rotated/archived logs

$ lnav -R /var/log/syslog

Run headless with command

$ lnav -n -c ":filter-in error" path/to/log

SYNOPSIS

lnav [-hHVCnqirRt] [-c CMD] [-f PATH] [-I PATH] [-d FILE] [-w FILE] [logfile1 logfile2 ...]

lnav is an advanced log file viewer that leverages semantic information from log files. It can interleave messages from multiple files, create time-based histograms, and provides efficient navigation through logs using hotkeys.

PARAMETERS

-h

Display help information

-H

Show internal help text

-V

Print version details

-n

Run in headless mode without UI

-c CMD

Execute command after loading files

-f PATH

Run commands from a configuration file

-I PATH

Add directory to configuration search path

-q

Quiet mode; suppress messages

-i

Install format files to user directory. Pass 'extra' to install the default set of third-party formats.

-u

Update installed format files from repositories

-a

Load all of the most recent log file types

-C

Validate configuration and log format files

-d FILE

Output debug messages to file

-r

Recursively load files from directories

-R

Include rotated and archived log files

-t

Add timestamps to stdin data

-w FILE

Write stdin content to file

CONFIGURATION

~/.lnav/formats/

Directory for user-defined log format files (JSON format definitions).

~/.lnav/configs/

Directory for user configuration files.

CAVEATS

Press "?" for online help while running, and "q" to exit. lnav automatically detects and parses many common log formats (syslog, Apache, strace, etc.). Custom formats can be defined in JSON configuration files. Use ":filter-in" and ":filter-out" commands to filter log lines interactively.

HISTORY

lnav was created to provide an advanced log file navigator with automatic format detection, syntax highlighting, and efficient navigation for system administrators and developers.