diff options
Diffstat (limited to 'docs/source/data.rst')
| -rw-r--r-- | docs/source/data.rst | 193 |
1 files changed, 193 insertions, 0 deletions
diff --git a/docs/source/data.rst b/docs/source/data.rst new file mode 100644 index 0000000..a7352e1 --- /dev/null +++ b/docs/source/data.rst @@ -0,0 +1,193 @@ + +.. _data-ext: + +Extracting Data +=============== + +**Note**: This feature is still in **BETA**, you should expect bugs and +incompatible changes in the future. + +Log messages contain a good deal of useful data, but it's not always easy to get +at. The log parser built into **lnav** is able to extract data as described by +:ref:`log_formats` as well as discovering data in plain text messages. This data +can then be queried and processed using the SQLite front-end that is also +incorporated into **lnav**. As an example, the following Syslog message from +:code:`sudo` can be processed to extract several key/value pairs:: + + Jul 31 11:42:26 Example-MacBook-Pro.local sudo[87024]: testuser : TTY=ttys004 ; PWD=/Users/testuser/github/lbuild ; USER=root ; COMMAND=/usr/bin/make install + +The data that can be extracted by the parser is viewable directly in **lnav** +by pressing the 'p' key. The results will be shown in an overlay like the +following:: + + Current Time: 2013-07-31T11:42:26.000 Original Time: 2013-07-31T11:42:26.000 Offset: +0.000 + Known message fields: + ├ log_hostname = Example-MacBook-Pro.local + ├ log_procname = sudo + ├ log_pid = 87024 + Discovered message fields: + ├ col_0 = testuser + ├ TTY = ttys004 + ├ PWD = /Users/testuser/github/lbuild + ├ USER = root + └ COMMAND = /usr/bin/make install + +Notice that the parser has detected pairs of the form '<key>=<value>'. The data +parser will also look for pairs separated by a colon. If there are no clearly +demarcated pairs, then the parser will extract anything that looks like data +values and assign them keys of the form 'col_N'. For example, two data values, +an IPv4 address and a symbol, will be extracted from the following log +message:: + + Apr 29 08:13:43 sample-centos5 avahi-daemon[2467]: Registering new address record for 10.1.10.62 on eth0. + +Since there are no keys for the values in the message, the parser will assign +'col_0' for the IP address and 'col_1' for the symbol, as seen here:: + + Current Time: 2013-04-29T08:13:43.000 Original Time: 2013-04-29T08:13:43.000 Offset: +0.000 + Known message fields: + ├ log_hostname = sample-centos5 + ├ log_procname = avahi-daemon + ├ log_pid = 2467 + Discovered message fields: + ├ col_0 = 10.1.10.62 + └ col_1 = eth0 + +Now that you have an idea of how the parser works, you can begin to perform +queries on the data that is being extracted. The SQLite database engine is +embedded into **lnav** and its `Virtual Table +<http://www.sqlite.org/vtab.html>`_ mechanism is used to provide a means to +process this log data. Each log format has its own table that can be used to +access all of the loaded messages that are in that format. For accessing log +message content that is more free-form, like the examples given here, the +**logline** table can be used. The **logline** table is recreated for each +query and is based on the format and pairs discovered in the log message at +the top of the display. + +Queries can be performed by pressing the semi-colon (;) key in **lnav**. After +pressing the key, the overlay showing any known or discovered fields will be +displayed to give you an idea of what data is available. The query can be any +`SQL query <http://sqlite.org/lang.html>`_ supported by SQLite. To make +analysis easier, **lnav** includes many extra functions for processing strings, +paths, and IP addresses. See :ref:`sql-ext` for more information. + +As an example, the simplest query to perform initially would be a "select all", +like so: + +.. code-block:: sql + + SELECT * FROM logline + +When this query is run against the second example log message given above, the +following results are received:: + + log_line log_part log_time log_idle_msecs log_level log_hostname log_procname log_pid col_0 col_1 + + 292 p.0 2013-04-11T16:42:51.000 0 info localhost avahi-daemon 2480 fe80::a00:27ff:fe98:7f6e eth0 + 293 p.0 2013-04-11T16:42:51.000 0 info localhost avahi-daemon 2480 10.0.2.15 eth0 + 330 p.0 2013-04-11T16:47:02.000 0 info localhost avahi-daemon 2480 fe80::a00:27ff:fe98:7f6e eth0 + 336 p.0 2013-04-11T16:47:02.000 0 info localhost avahi-daemon 2480 10.1.10.75 eth0 + 343 p.0 2013-04-11T16:47:02.000 0 info localhost avahi-daemon 2480 10.1.10.75 eth0 + 370 p.0 2013-04-11T16:59:39.000 0 info localhost avahi-daemon 2480 10.1.10.75 eth0 + 377 p.0 2013-04-11T16:59:39.000 0 info localhost avahi-daemon 2480 10.1.10.75 eth0 + 382 p.0 2013-04-11T16:59:41.000 0 info localhost avahi-daemon 2480 fe80::a00:27ff:fe98:7f6e eth0 + 401 p.0 2013-04-11T17:20:45.000 0 info localhost avahi-daemon 4247 fe80::a00:27ff:fe98:7f6e eth0 + 402 p.0 2013-04-11T17:20:45.000 0 info localhost avahi-daemon 4247 10.1.10.75 eth0 + + 735 p.0 2013-04-11T17:41:46.000 0 info sample-centos5 avahi-daemon 2465 fe80::a00:27ff:fe98:7f6e eth0 + 736 p.0 2013-04-11T17:41:46.000 0 info sample-centos5 avahi-daemon 2465 10.1.10.75 eth0 + 781 p.0 2013-04-12T03:32:30.000 0 info sample-centos5 avahi-daemon 2465 10.1.10.64 eth0 + 788 p.0 2013-04-12T03:32:30.000 0 info sample-centos5 avahi-daemon 2465 10.1.10.64 eth0 + 1166 p.0 2013-04-25T10:56:00.000 0 info sample-centos5 avahi-daemon 2467 fe80::a00:27ff:fe98:7f6e eth0 + 1167 p.0 2013-04-25T10:56:00.000 0 info sample-centos5 avahi-daemon 2467 10.1.10.111 eth0 + 1246 p.0 2013-04-26T06:06:25.000 0 info sample-centos5 avahi-daemon 2467 10.1.10.49 eth0 + 1253 p.0 2013-04-26T06:06:25.000 0 info sample-centos5 avahi-daemon 2467 10.1.10.49 eth0 + 1454 p.0 2013-04-28T06:53:55.000 0 info sample-centos5 avahi-daemon 2467 10.1.10.103 eth0 + 1461 p.0 2013-04-28T06:53:55.000 0 info sample-centos5 avahi-daemon 2467 10.1.10.103 eth0 + + 1497 p.0 2013-04-29T08:13:43.000 0 info sample-centos5 avahi-daemon 2467 10.1.10.62 eth0 + 1504 p.0 2013-04-29T08:13:43.000 0 info sample-centos5 avahi-daemon 2467 10.1.10.62 eth0 + +Note that **lnav** is not returning results for all messages that are in this +syslog file. Rather, it searches for messages that match the format for the +given line and returns only those messages in results. In this case, that +format is "Registering new address record for <IP> on <symbol>", which +corresponds to the parts of the message that were not recognized as data. + +More sophisticated queries can be done, of course. For example, to find out the +frequency of IP addresses mentioned in these messages, you can run: + +.. code-block:: sql + + SELECT col_0,count(*) FROM logline GROUP BY col_0 + +The results for this query are:: + + col_0 count(*) + + 10.0.2.15 1 + 10.1.10.49 2 + 10.1.10.62 2 + 10.1.10.64 2 + 10.1.10.75 6 + 10.1.10.103 2 + 10.1.10.111 1 + fe80::a00:27ff:fe98:7f6e 6 + +Since this type of query is fairly common, **lnav** includes a "summarize" +command that will compute the frequencies of identifiers as well as min, max, +average, median, and standard deviation for number columns. In this case, you +can run the following to compute the frequencies and return an ordered set of +results:: + + :summarize col_0 + + +Recognized Data Types +--------------------- + +When searching for data to extract from log messages, **lnav** looks for the +following set of patterns: + + +Strings + Single and double-quoted strings. Example: "The quick brown fox." + +URLs + URLs that contain the '://' separator. Example: http://example.com + +Paths + File system paths. Examples: /path/to/file, ./relative/path + +MAC Address + Ethernet MAC addresses. Example: c4:2c:03:0e:e4:4a + +Hex Dumps + A colon-separated string of hex numbers. Example: e8:06:88:ff + +Date/Time + Date and time stamps of the form "YYYY-mm-DD" and "HH:MM:SS". + +IP Addresses + IPv4 and IPv6 addresses. Examples: 127.0.0.1, fe80::c62c:3ff:fe0e:e44a%en0 + +UUID + The common formatting for 128-bit UUIDs. Example: + 0E305E39-F1E9-4DE4-B10B-5829E5DF54D0 + +Version Numbers + Dot-separated version numbers. Example: 3.7.17 + +Numbers + Numbers in base ten, hex, and octal formats. Examples: 1234, 0xbeef, 0777 + +E-Mail Address + Strings that look close to an e-mail address. Example: gary@example.com + +Constants + Common constants in languages, like: true, false, null, None. + +Symbols + Words that follow the common conventions for symbols in programming + languages. For example, containing all capital letters, or separated + by colons. Example: SOME_CONSTANT_VALUE, namespace::value |