Splunk Quick Reference Guide
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QUICK REFERENCE GUIDE Concepts Events An event is a set of values associated with a timestamp. It is a single entry of data and can have one or multiple lines. An event can be a text document, a configuration file, an entire stack trace, and so on. This is an example of an event in a web activity log: 10.14.0.172 - - [01/ Mar/2015:12:05:27 -0700] “GET / trade/app?action=logout HTTP/1.1” 200 2953 You can also define transactions to search for and group together events that are conceptually related but span a duration of time. Transactions can represent a multistep business-related activity, such as all events related to a single customer session on a retail website. Host, Source, and Source Type A host is the name of the physical or virtual device where an event originates. The host field provides an easy way to find all data originating from a specific device. A source is the name of the file, directory, data stream, or other input from which a particular event originates. Sources are classified into source types, which can be either well known formats or formats defined by the user. Some common source types are HTTP web server logs and Windows event logs. Events with the same source types can come from different sources. For example, events from the file source=/var/log/messages and from a syslog input port source=UDP:514 often share the source type, sourcetype=linux_ syslog Fields At search-time, indexed events that match a specified search string can be categorized into event types. Indexes When data is added, Splunk software parses the data into individual events, extracts the timestamp, applies line-breaking rules, and stores the events in an index. You can create new indexes for different inputs. By default, data is stored in the "main" index. Events are retrieved from one or more indexes during a search. Index-Time and Search-Time During index-time processing, data is read from a source on a host and is classified into a source type. Timestamps are extracted, and the data is parsed into individual events. Line-breaking rules are applied to segment the events to display in the search results. Each event is written to an index on disk, where the event is later retrieved with a search request. When a search starts, referred to as search-time, indexed events are retrieved from disk. Fields are extracted from the raw text for the event. Core Features Search Search is the primary way users navigate data in Splunk software. You can write a search to retrieve events from an index, use statistical commands to calculate metrics and generate reports, search for specific conditions within a rolling time window, identify patterns in your data, predict future trends, and so on. You transform the events using the Splunk Search Process Language (SPL™). Searches can be saved as reports and used to power dashboards. Reports Fields are searchable name and value pairings that distinguish one event from another. Not all events have the same fields and field values. Using fields, you can write tailored searches to retrieve the specific events that you want. When Splunk software processes events at index-time and search-time, the software extracts fields based on configuration file definitions and userdefined patterns. Reports are saved searches and pivots. You can run reports on an ad hoc basis, schedule reports to run on a regular interval, or set a scheduled report to generate alerts when the results meet particular conditions. Reports can be added to dashboards as dashboard panels. Use the Field Extractor tool to automatically generate and validate field extractions at searchtime. Regular expressions are automatically generated to extract fields. You can extract fields from events where values are separated by spaces, commas, or other characters. Dashboards are made up of panels that contain modules such as search boxes, fields, and data visualizations. Dashboard panels are usually connected to saved searches or pivots. They can display the results of completed searches, as well as data from real-time searches. Tags and Event Types Tags are aliases for particular field values. You can assign one or more tags to any field name/ value combination, including event types, hosts, sources, and source types. Use tags to group related field values together, or to track abstract field values such as IP addresses or ID numbers by giving them more descriptive names. Dashboards Alerts Alerts are triggered when search results meet specific conditions. You can use alerts on historical and real-time searches. Alerts can be configured to trigger actions such as sending alert information to designated email addresses or posting alert information to a web resource. Additional Features (Splunk Enterprise only) Data Model A data model is a hierarchically-organized collection of datasets that Pivot uses to generate reports. Data model objects represent individual datasets, which the data model is composed of. Pivot Pivot refers to the table, chart, or other visualization you create using the Pivot Editor. You can map attributes defined by data model objects to data visualizations, without manually writing the searches. Pivots can be saved as reports and used to power dashboards. Apps Apps are a collection of configurations, knowledge objects, and customer designed views and dashboards. Apps extend the Splunk environment to fit the specific needs of organizational teams such as Unix or Windows system administrators, network security specialists, website managers, business analysts, and so on. A single Splunk Enterprise or Splunk Cloud installation can run multiple apps simultaneously. Distributed Search A distributed search provides a way to scale your deployment by separating the search management and presentation layer from the indexing and search retrieval layer. You use search to facilitate horizontal scaling for enhanced performance, to control access to indexed data, and to manage geographically dispersed data. Splunk Components Forwarders A Splunk instance that forwards data to another Splunk instance is referred to as a forwarder. Indexer An indexer is the Splunk instance that indexes data. The indexer transforms the raw data into events and stores the events into an index. The indexer also searches the indexed data in response to search requests. The search peers are indexers that fulfill search requests from the search head. Search Head In a distributed search environment, the search head is the Splunk instance that directs search requests to a set of search peers and merges the results back to the user. If the instance does only search and not indexing, it is usually referred to as a dedicated search head. Search Processing Language A Splunk search is a series of commands and arguments. Commands are chained together with a pipe "|" character to indicate that the output of one command feeds into the next command on the right. search | command1 arguments1 | command2 arguments2 | ... At the start of the search pipeline is an implied search command to retrieve events from the index. Search requests are written with keywords, quoted phrases, boolean expressions, wildcards, field name/value pairs, and comparison expressions. The AND operator is implied between search terms. For example: Subsearches A subsearch runs its own search and returns the results to the parent command as the argument value. The subsearch is run first and is contained in square brackets. For example, the following search uses a subsearch to find all syslog events from the user that had the last login error: Command Description chart/ timechart Returns results in a tabular output for (time-series) charting. dedup Removes subsequent results that match a specified criterion. eval Calculates an expression. See COMMON EVAL FUNCTIONS. fields Removes fields from search results. head/tail Returns the first/last N results. lookup Adds field values from an external source. rename Renames a field. Use wildcards to specify multiple fields. Use Fast Mode to increase the speed of searches by reducing the event data that they return. rex Specifies regular expression named groups to extract fields. Search as specifically as you can. For example, fatal_error not *error* search Filters results to those that match the search expression. sort Sorts the search results by the specified fields. stats Provides statistics, grouped optionally by fields. See COMMON STATS FUNCTIONS. table Specifies fields to keep in the result set. Retains data in tabular format. top/rare Displays the most/least common values of a field. transaction Groups search results into transactions. where Filters search results using eval expressions. Used to compare two different fields. sourcetype=syslog [ search login error | return 1 user ] Optimizing Searches The key to fast searching is to limit the data that needs to be pulled off disk to an absolute minimum. Then filter that data as early as possible in the search so that processing is done on the minimum data necessary. sourcetype=access_combined error | top 5 uri Partition data into separate indexes, if you will rarely perform searches across multiple types of data. For example, put web data in one index, and firewall data in another. This search retrieves indexed web activity events that contain the term "error". For those events, it returns the top 5 most common URI values. Limit the time range to only what is needed. For example -1h not -1w, or earliest=-1d. Search commands are used to filter unwanted events, extract more information, calculate values, transform, and statistically analyze the indexed data. Think of the search results retrieved from the index as a dynamically created table. Each indexed event is a row. The field values are columns. Each search command redefines the shape of that table. For example, search commands that filter events will remove rows, search commands that extract fields will add columns. Time Modifiers You can specify a time range to retrieve events inline with your search by using the latest and earliest search modifiers. The relative times are specified with a string of characters to indicate the amount of time (integer and unit) and an optional "snap to" time unit. The syntax is: [+|-]@ The search "error earliest=-1d@d latest=-h@h" retrieves events containing "error" that occurred yesterday snapping to the beginning of the day (00:00:00) and through to the most recent hour of today, snapping on the hour. The snap to time unit rounds the time down. For example, if it is 11:59:00 and you snap to hours (@h), the time used is 11:00:00 not 12:00:00. You can also snap to specific days of the week using @w0 for Sunday, @w1 for Monday, and so on. Common Search Commands Filter out results as soon as possible before calculations. Use field-value pairs, before the first pipe. For example, ERROR status=404 |… instead of ERROR | search status=404… Or use filtering commands such as where. Filter out unnecessary fields as soon as possible in the search. Postpone commands that process over the entire result set (non-streaming commands) as late as possible in your search. Some of these commands are: dedup, sort, and stats. Use post-processing searches in dashboards. Use summary indexing, report acceleration, and data model acceleration features. www.splunk.com docs.splunk.com Splunk Inc. 250 Brannan Street San Francisco, CA 94107 Copyright © 2015 Splunk Inc. All rights reserved. Splunk, Splunk>, Listen to Your Data, The Engine for Machine Data, Hunk, Splunk Cloud, Splunk Light, SPL and Splunk MINT are trademarks and registered trademarks of Splunk Inc. in the United States and other countries. All other brand names, product names, or trademarks belong to their respective owners. Item # SPLUNK-Reference-Guide-Pages-117 Common Eval Functions The eval command calculates an expression and puts the resulting value into a field (e.g. “...| eval force = mass * acceleration”). The following table lists some of the functions used with the eval command. You can also use basic arithmetic operators (+ - * / %), string concatenation (e.g., ‘...| eval name = last . “,” . last’), and Boolean operations (AND OR NOT XOR < > <= >= != = == LIKE). Function Description Examples abs(X) Returns the absolute value of X. abs(number) case(X,"Y",…) Takes pairs of arguments X and Y, where X arguments are Boolean expressions. When evaluated to TRUE, the arguments return the corresponding Y argument. case(error == 404, "Not found", error == 500,"Internal Server Error", error == 200, "OK") ceil(X) Ceiling of a number X. ceil(1.9) Identifies IP addresses that belong to a particular subnet. cidrmatch("10.14.0.172/25",ip) Returns the first value that is not null. coalesce(null(), "Returned val", null()) cos(X) Calculates the cosine of X. n=cos(0) exact(X) exact(3.14*num) exp(X) Evaluates an expression X using double precision floating point arithmetic. Returns ex. if(X,Y,Z) If X evaluates to TRUE, the result is the second argument Y. If X evaluates to FALSE, the result evaluates to the third argument Z. if(error==200, "OK", "Error") isbool(X) Returns TRUE if X is Boolean. isbool(field) Returns TRUE if X is an integer. isint(field) Returns TRUE if X is NULL. isnull(field) Returns TRUE if X is a string. isstr(field) This function returns the character length of a string X. len(field) cidrmatch("X",Y) coalesce(X,…) isint(X) isnull(X) isstr() len(X) exp(3) like(X,"Y") Returns TRUE if and only if X is like the SQLite pattern in Y. like(field, "addr%") log(X,Y) Returns the log of the first argument X using the second argument Y as the base. Y defaults to 10. log(number,2) lower(X) Returns the lowercase of X. lower(username) ltrim(X,Y) Returns X with the characters in Y trimmed from the left side. Y defaults to spaces and tabs. ltrim(" ZZZabcZZ ", " Z") match(X,Y) Returns if X matches the regex pattern Y. match(field, "^\d{1,3}\.\d$") Returns the maximum. max(delay, mydelay) Returns the MD5 hash of a string value X. md5(field) max(X,…) md5(X) min(X,…) Returns the minimum. mvcount(X) min(delay, mydelay) Returns the number of values of X. mvcount(multifield) mvfilter(X) Filters a multi-valued field based on the Boolean expression X. mvfilter(match(email, "net$")) mvindex(X,Y,Z) Returns a subset of the multivalued field X from start position (zero-based) Y to Z (optional). mvindex(multifield, 2) mvjoin(X,Y) Given a multi-valued field X and string delimiter Y, and joins the individual values of X using Y. mvjoin(address, ";") now() Returns the current time, represented in Unix time. null() now() This function takes no arguments and returns NULL. null() nullif(X,Y) Given two arguments, fields X and Y, and returns the X if the arguments are different. Otherwise returns NULL. nullif(fieldA, fieldB) random() Returns a pseudo-random number ranging from 0 to 2147483647. random() relative_ time(X,Y) Given epochtime time X and relative time specifier Y, returns the epochtime value of Y applied to X. relative_time(now(),"-1d@d") replace(X,Y,Z) Returns a string formed by substituting string Z for every occurrence of regex string Y in string X. Returns date with the month and day numbers switched, so if the input was 4/30/2015 the return value would be 30/4/2009: replace(date, "^(\d{1,2})/ (\d{1,2})/", "\2/\1/") Common Eval Functions (continued) Function Description Examples round(X,Y) Returns X rounded to the amount of decimal places specified by Y. The default is to round to an integer. round(2.555, 2) rtrim(X,Y) Returns X with the characters in Y trimmed from the right side. If Y is not specified, spaces and tabs are trimmed. rtrim(" ZZZZabcZZ ", " Z") searchmatch(X) Returns true if the event matches the search string X. searchmatch("foo AND bar") Returns X as a multi-valued field, split by delimiter Y. sqrt(X) split(address, ";") Returns the square root of X. sqrt(9) strftime(X,Y) Returns epochtime value X rendered using the format specified by Y. strftime(_time, "%H:%M") strptime(X,Y) Given a time represented by a string X, returns value parsed from format Y. strptime(timeStr, "%H:%M") substr(X,Y,Z) Returns a substring field X from start position (1-based) Y for Z (optional) characters. substr("string", 1, 3) time() Returns the wall-clock time with microsecond resolution. time() tonumber(X,Y) Converts input string X to a number, where Y (optional, defaults to 10) defines the base of the number to convert to. tonumber("0A4",16) tostring(X,Y) Returns a field value of X as a string. If the value of X is a number, it reformats it as a string. If X is a Boolean value, reformats to "True" or "False". If X is a number, the second argument Y is optional and can either be "hex" (convert X to hexadecimal), "commas" (formats X with commas and 2 decimal places), or "duration" (converts seconds X to readable time format HH:MM:SS). This example returns: foo=615 and foo2=00:10:15: … | eval foo=615 | eval foo2 = tostring(foo, “duration”) typeof(X) Returns a string representation of the field type. This example returns: “NumberStringBoolInvalid”: typeof(12)+ typeof(“string”)+ urldecode(X) Returns the URL X decoded. urldecode("http%3A%2F%2Fwww.splunk. com%2Fdownload%3Fr%3Dheader") validate (X,Y,…) Given pairs of arguments, Boolean expressions X and strings Y, returns the string Y corresponding to the first expression X that evaluates to False and defaults to NULL if all are True. validate(isint(port), "ERROR: Port is not an integer", port >= 1 AND port <= 65535, "ERROR: Port is out of range") split(X,"Y") Common Stats Functions avg(X) count(X) dc(X) earliest(X) latest(X) max(X) median(X) min(X) mode(X) perc (Y) range(X) stdev(X) stdevp(X) sum(X) sumsq(X) values(X) var(X) Common statistical functions used with the chart, stats, and timechart commands. Field names can be wildcarded, so avg(*delay) might calculate the average of the delay and xdelay fields. Returns the average of the values of field X. Returns the number of occurrences of the field X. To indicate a specific field value to match, format X as eval(field="value"). Returns the count of distinct values of the field X. Returns the chronologically earliest seen value of X. Returns the chronologically latest seen value of X. Returns the maximum value of the field X. If the values of X are non-numeric, the max is found from alphabetical ordering. Returns the middle-most value of the field X. Returns the minimum value of the field X. If the values of X are non-numeric, the min is found from alphabetical ordering. Returns the most frequent value of the field X. Returns the X-th percentile value of the field Y. For example, perc5(total) returns the 5th percentile value of a field "total". Returns the difference between the max and min values of the field X. Returns the sample standard deviation of the field X. Returns the population standard deviation of the field X. Returns the sum of the values of the field X. Returns the sum of the squares of the values of the field X. Returns the list of all distinct values of the field X as a multi-value entry. The order of the values is alphabetical. Returns the sample variance of the field X. Search Examples Reporting (cont.) Filter Results Filter results to only include those with “fail” in their raw text and status=0. … | search fail status=0 Remove duplicates of results with the same host value. … | dedup host Keep only search results whose "_raw" field contains IP addresses in the non-routable class A (10.0.0.0/8). … | regex _raw="(?.*) To: (? .*)" Save the running total of "count" in a field called "total_count". … | accum count as total_count … | delta count as countdiff … | rename _ip as IPAddress Return the maximum "delay" by "size", where "size" is broken down into a maximum of 10 equal sized buckets. … | chart max(delay) by size bins=10 For each event where "count" exists, compute the difference between count and its previous value and store the result in "countdiff". Return max(delay) for each value of foo. … | chart max(delay) over foo Rename the "_ip" field as "IPAddress". Return max(delay) for each value of foo split by the value of bar. … | chart max(delay) over foo by bar Count the events by "host" … | stats count by host Search Examples (continued) Lookup Tables (Splunk Enterprise only) Multi-Valued Fields For each event, use the lookup table usertogroup to locate the matching “user” value from the event. Output the group field value to the event. … | lookup usertogroup user OUTPUT group Combine the multiple values of the recipients field into a single value. … | nomv recipients Read in the usertogroup lookup table that is defined in the transforms.conf file. … | inputlookup usertogroup Separate the values of the "recipients" field into multiple field values, displaying the top recipients. … | makemv delim="," recipients | top recipients … | outputlookup users.csv … | mvexpand recipients Write the search results to the lookup file “users.csv”. Create new results for each value of the multivalue field "recipients". Find the number of recipient values. … | eval to_count = mvcount(recipients) Find the first email address in the recipient field. … | eval recipient _ first = mvindex(recipient,0) Find all recipient values that end in .net or .org. … | eval netorg_ recipients = mvfilter match(recipient,"\.net$") OR match(recipient,"\.org$")) Find the index of the first recipient value match “\.org$” … | eval orgindex = mvfind(recipient, "\.org$") Regular Expressions (Regexes) Regular Expressions are useful in multiple areas: search commands regex and rex; eval functions match() and replace(); and in field extraction. Regex Note Example Explanation \s white space \d\s\d digit space digit \S not white space \d\S\d digit nonwhitespace digit \d digit \d\d\d-\d\d\d\d\d\d SSN \D not digit \D\D\D three non-digits \w word character (letter, number, or _) Common Date and Time Formatting Use these values for eval functions strftime() and strptime(), and for timestamping event data. Regex Example Explanation %H 24 hour (leading zeros) (00 to 23) %I 12 hour (leading zeros) (01 to 12) %M Minute (00 to 59) %S Second (00 to 61) %N subseconds with width (%3N = millisecs, %6N = microsecs, %9N = nanosecs) \w\w\w three word chars \W not a word character \W\W\W three non-word chars [...] any included character [a-z0-9#] any char that is a thru z, 0 thru 9, or # [^...] no included character [^xyz] any char but x, y, or z %p AM or PM %Z Time zone (EST) %z Time zone offset from UTC, in hour and minute: +hhmm or -hhmm. (-0500 for EST) %s Seconds since 1/1/1970 (1308677092) %d Day of month (leading zeros) (01 to 31) %j Day of year (001 to 366) %w Weekday (0 to 6) %a Abbreviated weekday (Sun) %A Weekday (Sunday) %b Abbreviated month name (Jan) %B Month name (January) %m Month number (01 to 12) %y Year without century (00 to 99) %Y Year (2015) %Y-%m-%d 2014-12-31 %y-%m-%d 14-12-31 %b %d, %Y Jan 24, 2015 %B %d, %Y January 24, 2015 q|%d %b '%y = %Y-%m-%d| q|25 Feb '15 = 2015-02-25| * zero or more \w* zero or more words chars + one or more \d+ integer ? zero or one \d\d\d-?\d\d?\d\d\d\d SSN with dashes being optional or \w|\d word or digit character named extraction (?P \ d\d\d-\d\d\d\d\d\d) pull out a SSN and assign to 'ssn' field (?: ... ) logical or atomic grouping (?:[a-zAZ]|\d) alphabetic character OR a digit ^ start of line ^\d+ line begins with at least one digit $ end of line \d+$ line ends with at least one digit {...} number of repetitions \d{3,5} between 3-5 digits \ escape \[ escape the [ character | (?P...) Time Days Months Years Examples
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