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READMElast updated: Mon 02/12/18 at 07:09:46 AM by
LNAV -- The Logfile Navigator
The log file navigator, lnav, is an enhanced log file viewer that takes advantage of any semantic information that can be gleaned from the files being viewed, such as timestamps and log levels. Using this extra semantic information, lnav can do things like interleaving messages from different files, generate histograms of messages over time, and providing hotkeys for navigating through the file. It is hoped that these features will allow the user to quickly and efficiently zero in on problems.
The following software packages are required to build lnav:
- gcc/clang - A C++14-compatible compiler.
- libpcre - The Perl Compatible Regular Expression (PCRE) 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.
Lnav follows the usual GNU style for configuring and installing software:
$ ./configure $ make $ sudo make install
./autogen.sh before running any of the above commands when
compiling from a cloned repository.
It should compile fine in Cygwin.
Alternatively, you can get the generated binary from AppVeyor artifacts.
Remember that you still need the lnav dependencies under Cygwin, here is a quick way to do it:
setup-x86_64.exe -q -P libpcre1 -P libpcrecpp0 -P libsqlite3_0 -P libstdc++6
Currently, the x64 version seems to be working better than the x86 one.
The only file installed is the executable,
lnav. You can execute it
with no arguments to view the default set of files:
You can view all the syslog messages by running:
$ lnav /var/log/messages*
On systems running
systemd-journald, you can use
lnav as the pager:
$ journalctl | lnav
or in follow mode:
$ journalctl -f | lnav
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
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
The following screenshot shows a syslog file. Log lines are displayed with highlights. Errors are red and warnings are yellow.
The lnav website can be found at: