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508 lines
22 KiB
Plaintext
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lnav - A fancy log file viewer
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DESCRIPTION
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-----------
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The log file navigator, lnav, is an enhanced log file viewer that
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takes advantage of any semantic information that can be gleaned from
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the files being viewed, such as timestamps and log levels. Using this
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extra semantic information, lnav can do things like interleaving
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messages from different files, generate histograms of messages over
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time, and providing hotkeys for navigating through the file. It is
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hoped that these features will allow the user to quickly and
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efficiently zero in on problems.
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OPTIONS
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-------
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Lnav takes a list of files to view and/or you can use the flag
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arguments to load well-known log files, such as the syslog or apache
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log files. The flag arguments are:
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-s Load the most recent syslog messages file. (Default)
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-a Load all of the most recent log file types.
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-r Load older rotated log files as well.
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When using the flag arguments, lnav will look for the files relative
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to the current directory and its parent directories. In other words,
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if you are working within a directory that has the well-known log
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files, those will be preferred over any others.
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Any files given on the command-line are scanned to determine their log
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file format and to create an index for each line in the file. You do
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not have to manually specify the log file format. The currently
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supported formats are: syslog, apache, strace, tcsh history, and
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generic log files with timestamps.
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Lnav will also display data piped in on the standard input. The
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following options are available when doing so:
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-t Prepend timestamps to the lines of data being read in
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on the standard input.
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-w file Write the contents of the standard input to this file.
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DISPLAY
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-------
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The main part of the display shows the log lines from the files interleaved
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based on time-of-day. New lines are automatically loaded as they are appended
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to the files and, if you are viewing the bottom of the files, lnav will scroll
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down to display the new lines, much like 'tail -f'.
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On color displays, the lines will be highlighted as follows:
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* Errors will be colored in red;
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* warnings will be yellow;
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* boundaries between days will be underlined; and
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* various color highlights will be applied to: IP addresses, SQL keywords,
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XML tags, file and line numbers in Java backtraces, and quoted strings.
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To give you an idea of where you are in the file spatially, the right
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side of the display has a proportionally sized 'scrollbar' that
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indicates your current position in the file.
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Above and below the main body are status lines that display:
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* the current time;
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* the name of the file the top line was pulled from;
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* the log format for the top line;
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* the current view;
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* the line number for the top line in the display;
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* the total number of warnings and errors;
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* the number of search hits, which updates as more are found; and
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* the number of lines not displayed because of filtering.
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Finally, the last line on the display is where you can enter search
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patterns and execute internal commands, such as converting a
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unix-timestamp into a human-readable date. The command-line is by
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the readline library, so the usual set of keyboard shortcuts can
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be used.
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The body of the display is also used to display other content, such
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as: the help file, histograms of the log messages over time, and
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SQL results. The views are organized into a stack so that any time
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you activate a new view with a key press or command, the new view
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is pushed onto the stack. Pressing the same key again will pop the
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view off of the stack and return you to the previous view. Note
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that you can always use 'q' to pop the top view off of the stack.
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KEY BINDINGS
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------------
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To help navigate through the file there are many hotkeys that should
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make it easy to zero-in on a specific section of the file or scan
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through the file.
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? View/leave this help message.
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q Leave the current view or quit the program when in
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the log file view.
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home Move to the top of the file.
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end Move to the end of the file. If the view is already
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at the end, it will move to the last line.
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space/pgdn Move down a page.
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b/bs/pgup Move up a page.
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j/cr/down-arrow Move down a line.
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k/up-arrow Move up a line.
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h/left-arrow Move to the left.
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l/right-arrow Move to the right.
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e/E Move to the next/previous error.
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w/W Move to the next/previous warning.
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n/N Move to the next/previous search hit.
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f/F Move to the next/previous file. In the log view, this
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moves to the next line from a different file. In the
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text view, this rotates the view to the next file.
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>/< Move horizontally to the next/previous search hit.
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s Toggle "scrubbing" of log lines in the log view. Log
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formats that support scrubbing will try to eliminate
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redundant information on a single line. For example, the
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year part of a timestamp or the log level text.
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t Switch to/from the text file view. The text file view is
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for any files that are not recognized as log files.
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o/O Move forward/backward 60 minutes from the current
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position in the log file.
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d/D Move forward/backward 24 hours from the current
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position in the log file.
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1-6/Shift 1-6 Move to the next/previous n'th ten minute of the
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hour. For example, '4' would move to the first
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log line in the fortieth minute of the current
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hour in the log. And, '6' would move to the next
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hour boundary.
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0/Shift 0 Move to the next/previous day boundary.
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m Mark/unmark the line at the top of the display.
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The line will be highlighted with reverse video to
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indicate that it is a user bookmark. You can use
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the 'u' hotkey to iterate through marks you have
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added.
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M Mark/unmark all the lines between the top of the
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display and the last line marked/unmarked.
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J Mark/unmark the next line after the previously
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marked line.
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K Like 'J' except it toggles the mark on the
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previous line.
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c Copy the marked text to the X11 selection buffer or OS X
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clipboard.
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C Clear all marked lines.
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u/U Move forward/backward through any user bookmarks
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you have added using the 'm' key.
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T Toggle the display of the "time offset" column that shows
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the time elapsed since the beginning of the logs or the
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offset from the previous bookmark.
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i View/leave a histogram of the log messages over
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time. The histogram counts the number of
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displayed log lines for each bucket of time. The
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bars are layed out horizontally with colored
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segments representing the different log levels.
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You can use the 'z' hotkey to change the size of
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the time buckets (e.g. ten minutes, one hour, one
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day).
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I Switch between the log and histogram views while
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keeping the time displayed at the top of each view
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in sync. For example, if the top line in the log
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view is "11:40", hitting 'I' will switch to the
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histogram view and scrolled to display "11:00" at
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the top (if the zoom level is hours).
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z/Shift Z Zoom in or out one step in the histogram view.
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/<regexp> Start a search for the given regular expression.
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The search is live, so when there is a pause in
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typing, the currently running search will be
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canceled and a new one started. History is
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maintained for your searches so you can rerun them
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easily. If there is an error encountered while
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trying to interpret the expression, the error will
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be displayed in red on the status line. While the
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search is active, the 'hits' field in the status
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line will be green, when finished it will turn
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back to black.
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Note: The regular expression format used by is PCRE
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(Perl-Compatible Regular Expressions). For example,
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if you wanted to search for ethernet device names,
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regardless of their ID number, you can type:
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eth\d+
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You can find more information about Perl regular
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expressions at:
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http://perldoc.perl.org/perlre.html
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:<command> Execute an internal command. The commands are
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listed below. History is also supported in this
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context as well as tab-completion for commands and
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some arguments. The result of the command
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replaces the command you typed.
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;<sql> Execute an SQL query. Most supported log file
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formats provide a sqlite virtual table backend
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that can be used in queries. See the SQL section
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below for more information.
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CTRL+] Abort command-line entry started with '/', ':', or ';'.
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y/Y Move forward/backward through the log view based on the
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"log_line" column in the SQL result view.
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v Switch to/from the SQL result view.
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V Switch between the log and SQL result views while
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keeping the top line number in the log view in
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sync with the log_line column in the SQL view.
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For example, doing a query that selects for
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"log_idle_msecs" and "log_line", you can move the
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top of the SQL view to a line and hit 'V' to switch
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to the log view and move to the line number that was
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selected in the "log_line" column.
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TAB/Shift+TAB In the SQL result view, cycle through the columns that
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are graphed. Initially, all number values are displayed
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in a stacked graph. Pressing TAB will change the display
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to only graph the first column. Repeatedly pressing TAB
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will cycle through the columns until they are all graphed
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again.
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p Enable or disable the display of the fields that the
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log message parser knows about or has discovered.
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This overlay is temporarily enabled when the semicolon
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key (;) is pressed so that it is easier to write queries.
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X Close the current text file or log file.
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CTRL-R Reset the session state. This will save the current
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session state (filters, highlights) and then reset the
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state to the factory default.
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r/R Restore the next/previous session. The current session is
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saved and then the new state is restored.
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F2 Toggle mouse support.
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MOUSE SUPPORT (experimental)
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----------------------------
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If you are using Xterm, or a compatible terminal, you can use the mouse to
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mark lines of text and move the view by grabbing the scrollbar.
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NOTE: You need to manually enable this feature by setting the LNAV_EXP
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environment variable to "mouse".
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COMMANDS
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--------
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help Switch to this help text view.
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adjust-log-time <date>
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Change the time of the top log line to the given time.
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All other log lines in the same file will also be
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adjusted using the same offset. After the adjustment,
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the displayed timestamp will be rewritten to the new
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time and highlighted with a magenta color.
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This command is useful for lining up log files that
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have timestamps from different machines.
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unix-time <secs-or-date>
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Convert a unix-timestamp in seconds to a
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human-readable form or vice-versa.
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BEWARE OF TIMEZONE DIFFERENCES.
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current-time Print the current time in human-readable form and
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as a unix-timestamp.
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goto <line#|N%> Go to the given line number or N percent into the
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file.
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highlight <regex> Highlight strings that match the given regular
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expression.
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filter-in <regex> Only display lines that match the given regular
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expression. This command can be used multiple
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times to add more lines to the display. The number
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of lines that are filtered out will be shown in the
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bottom status bar as 'Not Shown'.
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filter-out <regex>
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Do not display lines that match the given regular
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expression. This command can be used multiple
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times to remove more lines from the display. If a
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'filter-in' expression is also active, it takes
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priority and the filter-out will remove lines that
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were matched by the 'filter-in'. The number
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of lines that are filtered out will be shown in the
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bottom status bar as 'Not Shown'.
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disable-filter <regex>
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Disable an active 'filter-in' or 'filter-out'
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expression.
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enable-filter <regex>
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Enable a inactive 'filter-in' or 'filter-out'
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expression.
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disable-word-wrap Disable word wrapping in the log and text file views.
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enable-word-wrap Enable word wrapping in the log and text file views.
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open <filename>[:<line>]
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Open the given file within lnav and, if it is a
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text file, switch to the text view and jump to
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the given line number.
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close Close the current text file or log file. You can also
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close the current file by pressing 'X'.
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graph <regex> Graph the value of numbers in the file(s) over
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time. The given regular expression should capture
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the number to be displayed. For example:
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my stats: (\d+\.\d+)
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Will graph all the "stats" values found in the
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file. XXX This is still mostly a toy...
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append-to <file> Append any marked lines to the given file.
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write-to <file> Write any marked lines to the given file.
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session <cmd> Add the given command to the session file
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(~/.lnav/session). Any commands listed in the session file
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are executed on startup. Only the highlight, word-wrap, and
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filter-related commands can be added to the session file.
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create-logline-table <table-name>
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Create an SQL table using the top line of the log view
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as a template. See the "SQL QUERIES" and "DYNAMIC LOG
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LINE TABLE" sections below for more information.
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delete-logline-table <table-name>
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Delete an SQL table created by the 'create-logline-table'
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command.
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SQL QUERIES (experimental)
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-----------
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Lnav has support for performing SQL queries on log files using the
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Sqlite3 "virtual" table feature. For all supported log file types,
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lnav will create tables that can be queried using the subset of SQL
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that is supported by Sqlite3. For example, to get the top ten URLs
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being accessed in any loaded Apache log files, you can execute:
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;select cs_uri_stem, count(*) as total from access_log
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group by cs_uri_stem order by total desc limit 10;
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The query result view shows the results as text and graphs any number
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values found in the result, much like the histogram view.
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The builtin set of log tables are listed below. Note that only the
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log messages that match a particular format can be queried by a
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particular table. You can find the file format and table name for
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the top log message by looking in the upper right hand corner of the
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log file view.
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The log table names are as follows:
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access_log Apache common access log format
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syslog_log Syslog format
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glog_log Google glog format
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strace_log Strace log format
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generic_log 'Generic' log format. This table contains messages
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from files that have a very simple format with a
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leading timestamp followed by the message.
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The columns available for the top log line in the view will
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automatically be displayed after pressing the semicolon (;) key.
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All log tables contain at least the following columns:
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log_line The line number in the file, starting at zero.
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log_time The time of the log entry.
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log_idle_msecs The amount of time, in milliseconds, between the
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current log message and the previous one.
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log_level The log level (e.g. info, error, etc...).
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log_path The full path to the file.
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log_text The raw line of text. Note that this column is
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not included in the result of a 'select *', but
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it does exist.
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The following tables include the basic columns as listed above and
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include a few more columns since the log file format is more
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structured.
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syslog_log
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log_hostname The hostname the message was received from.
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log_procname The name of the process that sent the message.
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log_pid The process ID of the process that sent the message.
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access_log (The column names are the same as those in the
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Microsoft LogParser tool.)
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c_ip The client IP address.
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cs_username The client user name.
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cs_method The HTTP method.
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cs_uri_stem The stem portion of the URI.
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cs_uri_query The query portion of the URI.
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cs_version The HTTP version string.
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sc_status The status number returned to the client.
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sc_bytes The number of bytes sent to the client.
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cs_referrer The URL of the referring page.
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cs_user_agent The user agent string.
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strace_log (Currently, you need to run strace with the
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"-tt -T" options so there are timestamps for
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each function call.)
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funcname The name of the syscall.
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result The result code.
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duration The amount of time spent in the syscall.
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arg0 - arg9 The arguments passed to the syscall.
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These tables are created dynamically and not stored in memory or on
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disk. If you would like to persist some information from the tables,
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you can attach another database and create tables in that database.
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For example, if you wanted to save the results from the earlier
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example of a top ten query into the "/tmp/topten.db" file, you can do:
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;attach database "/tmp/topten.db" as topten;
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;create table topten as select cs_uri_stem, count(*) as total
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from access_log group by cs_uri_stem order by total desc
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limit 10;
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DYNAMIC LOG LINE TABLE (experimental)
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----------------------
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(NOTE: This feature is still very new and not completely reliable yet,
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use with care.)
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For log formats that lack message structure, lnav can parse the log
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message and attempt to extract any data fields that it finds. This
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feature is available through the "logline" log table. This table is
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dynamically created and defined based on the message at the top of
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the log view. For example, given the following log message from "sudo",
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lnav will create the "logline" table with columns for "TTY", "PWD",
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"USER", and "COMMAND":
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May 24 06:48:38 Tim-Stacks-iMac.local sudo[76387]: stack : TTY=ttys003 ;
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PWD=/Users/stack/github/lbuild ; USER=root ;
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COMMAND=/bin/echo Hello, World!
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Queries executed against this table will then only return results for
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other log messages that have the same format. So, if you were to
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execute the following query while viewing the above line, you might
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get the following results:
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;select USER,COMMAND from logline;
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USER | COMMAND
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---- | -------------------------
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root | /bin/echo Hello, World!
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mal | /bin/echo Goodbye, World!
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The log parser works by examining each message for key/value pairs
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separated by an equal sign (=) or a colon (:). For example, in the
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previous example of a "sudo" message, the parser sees the "USER=root"
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string as a pair where the key is "USER" and the value is "root".
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If no pairs can be found, then anything that looks like a value is
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extracted and assigned a numbered column. For example, the following
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line is from "dhcpd":
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Sep 16 22:35:57 drill dhcpd: DHCPDISCOVER from 00:16:ce:54:4e:f3 via hme3
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In this case, the lnav parser recognizes that "DHCPDISCOVER", the MAC
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address and the "hme3" device name are values and not normal words. So,
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it builds a table with three columns for each of these values. The
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regular words in the message, like "from" and "via", are then used to
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find other messages with a similar format.
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If you would like to execute queries against log messages of different
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formats at the same time, you can use the 'create-logline-table' command
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to permanently create a table using the top line of the log view as a
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template.
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