lnav/test/expected/test_text_file.sh_e088ea61a5382458cc48a2607e2639e52b0be1da.out

Screenshot

The following screenshot shows a syslog file. Log lines are displayed
with highlights. Errors are red and warnings are yellow.

Screenshot[1][2]

 ▌[1] - file://{top_srcdir}/docs/assets/images/lnav-syslog-thumb.png 
 ▌[2] - file://{top_srcdir}/docs/assets/images/lnav-syslog.png       

Features

 • Log messages from different files are collated together
   into a single view
 • Automatic detection of log format
 • Automatic decompression of GZip and BZip2 files
 • Filter log messages based on regular expressions
 • Use SQL to analyze your logs
 • And more...

Installation

Download a statically-linked binary for Linux/MacOS from the release
page[1]

 ▌[1] - https://github.com/tstack/lnav/releases/latest#release-artifacts 

Usage

The only file installed is the executable,  lnav .  You can execute it
with no arguments to view the default set of files:

 ▌$ lnav                                  

You can view all the syslog messages by running:

 ▌$ lnav /var/log/messages*               

Usage with  systemd-journald 

On systems running  systemd-journald , you can use  lnav  as the
pager:

 ▌$ journalctl | lnav                     

or in follow mode:

 ▌$ journalctl -f | lnav                  

Since  journalctl 's default output format omits the year, if you are
viewing logs which span multiple years you will need to change the
output format to include the year, otherwise  lnav  gets confused:

 ▌$ journalctl -o short-iso | lnav        

It is also possible to use  journalctl 's json output format and  lnav
will make use of additional fields such as PRIORITY and _SYSTEMD_UNIT:

 ▌$ journalctl -o json | lnav             

In case some MESSAGE fields contain special characters such as ANSI
color codes which are considered as unprintable by journalctl,
specifying  journalctl 's  -a  option might be preferable in order to
output those messages still in a non-binary representation:

 ▌$ journalctl -a -o json | lnav          

If using systemd v236 or newer, the output fields can be limited to
the ones actually recognized by  lnav  for increased efficiency:

 ▌$ journalctl -o json --output-fields=MESSAGE,PRIORITY,_PID,SYSLOG_IDENTIFIER,_SYSTEMD_UNIT | lnav    

If your system has been running for a long time, for increased
efficiency you may want to limit the number of log lines fed into  lnav
, e.g. via  journalctl 's  -n  or  --since=...  options.

In case of a persistent journal, you may want to limit the number of
log lines fed into  lnav  via  journalctl 's  -b  option.

Support

Please file issues on this repository or use the discussions section.
The following alternatives are also available:

 • support@lnav.org[1]
 • Discord[2]
 • Google Groups[3]

 ▌[1] - mailto:support@lnav.org          
 ▌[2] - https://discord.gg/erBPnKwz7R    
 ▌[3] - https://groups.google.com/g/lnav 

Links

 • Main Site[1]
 • Documentation[2] on Read the Docs
 • Internal Architecture[3]

 ▌[1] - https://lnav.org                                 
 ▌[2] - https://docs.lnav.org                            
 ▌[3] - file://{top_srcdir}/ARCHITECTURE.md 

Contributing

 • Become a Sponsor on GitHub[1]

 ▌[1] - https://github.com/sponsors/tstack 

Building From Source

Prerequisites

The following software packages are required to build lnav:

 • gcc/clang  - A C++14-compatible compiler.
 • libpcre2   - The Perl Compatible Regular Expression v2
   (PCRE2) library.
 • sqlite     - The SQLite database engine.  Version 3.9.0
   or higher is required.
 • ncurses    - The ncurses text UI library.
 • readline   - The readline line editing library.
 • zlib       - The zlib compression library.
 • bz2        - The bzip2 compression library.
 • libcurl    - The cURL library for downloading files
   from URLs.  Version 7.23.0 or higher is required.
 • libarchive - The libarchive library for opening archive
   files, like zip/tgz.
 • wireshark  - The 'tshark' program is used to interpret
   pcap files.

Build

Lnav follows the usual GNU style for configuring and installing
software:

Run  ./autogen.sh  if compiling from a cloned repository.

 ▌$ ./configure                           
 ▌$ make                                  
 ▌$ sudo make install                     

See Also

Angle-grinder[1] is a tool to slice and dice log files on the
command-line. If you're familiar with the SumoLogic query language,
you might find this tool more comfortable to work with.

 ▌[1] - https://github.com/rcoh/angle-grinder