mirror of
https://github.com/tstack/lnav
synced 2024-11-09 19:10:52 +00:00
147 lines
4.9 KiB
Markdown
147 lines
4.9 KiB
Markdown
---
|
|
layout: page
|
|
title: Features
|
|
permalink: /features
|
|
---
|
|
|
|
* TOC
|
|
{:toc}
|
|
|
|
## Single Log View
|
|
|
|
All log file contents are merged into a single view based on message timestamps.
|
|
You no longer need to manually correlate timestamps across multiple windows or
|
|
figure out the order in which to view rotated log files. The color bars on the
|
|
left-hand side help to show which file a message belongs to.
|
|
|
|
|
|
|
|
## Automatic Log Format Detection
|
|
|
|
The log message format is automatically determined by lnav while scanning your
|
|
files. The following are some of the [formats that are built in by default](https://docs.lnav.org/en/latest/formats.html):
|
|
|
|
* Common Web Access Log format
|
|
* W3C Extended Log File Format
|
|
* logfmt
|
|
* CUPS page_log
|
|
* Syslog
|
|
* Glog
|
|
* VMware ESXi/vCenter Logs
|
|
* dpkg.log
|
|
* uwsgi
|
|
* "Generic" - Any message that starts with a timestamp
|
|
* Strace
|
|
* sudo
|
|
|
|
If your log file format is JSON-lines or can be matched by a PCRE regular
|
|
expression, you can define your own format in a
|
|
[JSON file](https://docs.lnav.org/en/latest/formats.html#defining-a-new-format).
|
|
|
|
GZIP'ed and BZIP2'ed files are also detected automatically and decompressed on-the-fly.
|
|
|
|
## Filters
|
|
|
|
Display only lines that match or do not match a set of regular expressions.
|
|
Useful for removing extraneous log lines that you are not interested in.
|
|
|
|
## Timeline View
|
|
|
|
The timeline view shows a histogram of messages over time. The number of
|
|
warnings and errors are highlighted in the display so that you can easily see
|
|
where problems have occurred. Once you have found a period of time that is of
|
|
interest, a key-press will take you back to the log message view at the
|
|
corresponding time.
|
|
|
|
|
|
|
|
## Pretty-Print View
|
|
|
|
The pretty-print view will reformat structured data, like XML or JSON, so that
|
|
it is easier to read. Simply press SHIFT+P in the log view to have all the
|
|
currently displayed lines pretty-printed.
|
|
|
|
The following screenshot shows an XML blob with no indentation:
|
|
|
|
|
|
|
|
After pressing SHIFT+P, the XML is pretty-printed for easier viewing:
|
|
|
|
|
|
|
|
## Query Logs Using SQL
|
|
|
|
Log files are directly used as the backing for SQLite virtual tables. This
|
|
means you can perform queries on messages without having to load the data into
|
|
an SQL database. For example, the screenshot below shows the result of
|
|
running the following query against an Apache access_log file:
|
|
|
|
```sql
|
|
SELECT c_ip, count(*), sum(sc_bytes) AS total FROM access_log
|
|
GROUP BY c_ip ORDER BY total DESC;
|
|
```
|
|
|
|
|
|
|
|
## "Live" Operation
|
|
|
|
Searches are done as you type; new log lines are automatically loaded and
|
|
searched as they are added; filters apply to lines as they are loaded; and, SQL
|
|
queries are checked for correctness as you type.
|
|
|
|
## Themes
|
|
|
|
The UI can be [customized through themes](https://lnav.readthedocs.io/en/latest/config.html#theme-definitions).
|
|
|
|
|
|
|
|
## Syntax Highlighting
|
|
|
|
Errors and warnings are colored in red and yellow, respectively. Highlights are
|
|
also applied to: SQL keywords, XML tags, file and line numbers in Java
|
|
backtraces, and quoted strings. The search and SQL query prompt are also
|
|
highlighted as you type, making it easier to see errors and matching brackets.
|
|
|
|
|
|
|
|
## Tab-completion
|
|
|
|
The command prompt supports tab-completion for almost all operations. For
|
|
example, when doing a search, you can tab-complete words that are displayed on
|
|
screen rather than having to do a copy & paste.
|
|
|
|
|
|
|
|
## Custom Keymaps
|
|
|
|
[Hotkeys can be customized](https://lnav.readthedocs.io/en/latest/config.html#keymap-definitions)
|
|
to run lnav commands or scripts.
|
|
|
|
## Sessions
|
|
|
|
Session information is saved automatically and restored when you are viewing the
|
|
same set of files. The current location in files, bookmarks, and applied filters
|
|
are all saved as part of the session.
|
|
|
|
## Headless Mode
|
|
|
|
The log processing features of lnav can be used in scripts if you have a canned
|
|
set of operations or queries that you want to perform regularly. You can enable
|
|
headless mode with the '-n' switch on the command-line and then use the '-c'
|
|
flag to specify the commands or queries you want to execute. For example, to get
|
|
the top 10 client IP addresses from an apache access log file and write the
|
|
results to standard out in CSV format:
|
|
|
|
```console
|
|
$ lnav -n \
|
|
-c ';SELECT c_ip, count(*) AS total FROM access_log GROUP BY c_ip ORDER BY total DESC LIMIT 10' \
|
|
-c ':write-csv-to -' \
|
|
access.log
|
|
|
|
c_ip,total
|
|
10.208.110.176,2989570
|
|
10.178.4.102,11183
|
|
10.32.110.197,2020
|
|
10.29.165.250,443
|
|
```
|