Splunk® Enterprise

Getting Data In

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Monitor files and directories

Splunk Enterprise has three file input processors: monitor, MonitorNoHandle, and upload.

For the most part, you can use monitor to add nearly all your data sources from files and directories. However, you might want to use upload to add one-time inputs, such as an archive of historical data.

On Windows systems, you can use MonitorNoHandle to monitor files which the system rotates automatically. MonitorNoHandle works only on Windows systems.

You can add inputs to monitor or upload using any of these methods:

You can add inputs to MonitorNoHandle using either the CLI or inputs.conf.

You can use the data preview feature to see how Splunk Enterprise will index a file's data. See "Overview of data preview" for details.

How monitor works in Splunk Enterprise

Specify a path to a file or directory and the Splunk Enterprise monitor processor consumes any new data written to that file or directory. This is how you can monitor live application logs such as those coming from Java 2 Platform Enterprise Edition (J2EE) or .NET applications, Web access logs, and so on. Splunk Enterprise continues to monitor and index the file or directory as new data appears. You can also specify a mounted or shared directory, including network file systems, so long as Splunk Enterprise can read from the directory. If the specified directory contains subdirectories, Splunk Enterprise recursively examines them for new files.

Splunk Enterprise checks for the file or directory specified in a monitor configuration on start and restart. If the file or directory is not present on start, Splunk Enterprise continues to check for it every 24 hours from the time of the last restart. Splunk Enterprise also scans subdirectories of monitored directories continuously. To add new inputs without restarting Splunk Enterprise, use Splunk Web or the CLI. If you want Splunk Enterprise to find potential new inputs automatically, use the crawl CLI command.

When using monitor, note the following:

  • On most file systems, files can be read even as they are being written to. However, Windows file systems have the ability to prevent files from being read while they are being written, and some Windows programs might use these modes, though most do not. If you need to read files while they are being written to, you can use the MonitorNoHandle input.
  • Files or directories can be included or excluded via whitelists and blacklists.
  • Upon restart, Splunk Enterprise continues processing files where it left off.
  • Splunk Enterprise decompresses archive files before it indexes them. It can handle these common archive file types: tar, gz, bz2, tar.gz, tgz, tbz, tbz2, zip, and z.
  • If you add new data to an existing archive file, Splunk Enterprise will re-index the entire file, not just the new data in the file. This can result in duplication of events.
  • Splunk Enterprise detects log file rotation and does not process renamed files it has already indexed (with the exception of .tar and .gz archives; for more information see "Log file rotation" in this manual).
  • The entire dir/filename path must not exceed 1024 characters.
  • Disabling or deleting a file-based input using the command line or System does not stop the input's files from being indexed. Rather, it stops files from being checked again, but all the initial content will be indexed. To stop all in-process data, you must restart the Splunk Enterprise server.
  • Splunk Enterprise does not index files with a .splunk filename extension. This is because Splunk Enterprise expects files with that extension to be metadata information files. If you need to index files with a .splunk extension, use the add oneshot CLI command.

Monitor inputs may overlap. So long as the stanza names are different, Splunk Enterprise treats them as independent stanzas and files matching the most specific stanza will be treated in accordance with its settings.

Why use upload or batch?

To index a static file once, select Upload a local file or Index a file on the Splunk server in Splunk Web. The file will not be monitored on an ongoing basis.

You can also use the CLI add oneshot or spool commands for the same purpose. See "Use the CLI" for details.

Use the batch input type in inputs.conf to load files once and destructively. By default, the Splunk batch processor is located in $SPLUNK_HOME/var/spool/splunk. If you move a file into this directory, Splunk indexes it and then deletes it.

Note: For best practices on loading file archives, see "How to index different sized archives" on the Community Wiki.

Why use MonitorNoHandle?

This Windows-only input allows you to read files on Windows systems as Windows writes to them. It does this by using a kernel-mode filter driver to capture raw data as it gets written to the file. Use this input stanza on files which get locked open for writing. You can use this input stanza on a file which the system locks open for writing, such as the Windows DNS server log file.

Note: You can only monitor single files with MonitorNoHandle. You can not monitor directories. If a file you choose to monitor already exists, Splunk does not index its current contents, only new information that comes into the file as it gets written to.

Last modified on 22 May, 2015
What Splunk Enterprise does with your data (and how to make it do it better)
Use Splunk Web

This documentation applies to the following versions of Splunk® Enterprise: 6.0, 6.0.1, 6.0.2, 6.0.3, 6.0.4, 6.0.5, 6.0.6, 6.0.7, 6.0.8, 6.0.9, 6.0.10, 6.0.11, 6.0.12, 6.0.13, 6.0.14, 6.0.15, 6.1, 6.1.1, 6.1.2, 6.1.3, 6.1.4, 6.1.5, 6.1.6, 6.1.7, 6.1.8, 6.1.9, 6.1.10, 6.1.11, 6.1.12, 6.1.13, 6.1.14

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