[[command-line-flags]]
=== Command-line flags

Logstash has the following flags. You can use the `--help` flag to display this information.

[source,shell]
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-f, --config CONFIGFILE
 Load the Logstash config from a specific file, directory, or a wildcard. If
 given a directory or wildcard, config files will be read from the directory in
 alphabetical order.

-e CONFIGSTRING
 Use the given string as the configuration data. Same syntax as the config file.
 If not input is specified, 'stdin { type => stdin }' is default. If no output
 is specified, 'stdout { codec => rubydebug }}' is default.

-w, --filterworkers COUNT
 Sets the number of pipeline workers (threads) to run for filter and output
 processing (default: half the number of cores).
 If you find that events are backing up, or that the CPU is not saturated, consider increasing
 this number to better utilize machine processing power.

-b, --pipeline-batch-size SIZE
 This parameter defines the maximum number of events an individual worker thread will collect
 before attempting to execute its filters and outputs. Larger batch sizes are generally more 
 efficient, but come at the cost of increased memory overhead. You may have to increase the 
 JVM heap size by setting the `LS_HEAP_SIZE` variable to effectively use the option.

-u, --pipeline-batch-delay DELAY_IN_MS
 When creating pipeline event batches, how long to wait while polling for the next event. 

-l, --log FILE
 Log to a given path. Default is to log to stdout

--verbose
 Increase verbosity to the first level (info), less verbose.

--debug
 Increase verbosity to the last level (trace), more verbose.

-V, --version
  Display the version of Logstash.

-p, --pluginpath
  A path of where to find plugins. This flag can be given multiple times to include
  multiple paths. Plugins are expected to be in a specific directory hierarchy:
  'PATH/logstash/TYPE/NAME.rb' where TYPE is 'inputs' 'filters', 'outputs' or 'codecs'
  and NAME is the name of the plugin.

-t, --configtest
  Checks configuration and then exit. Note that grok patterns are not checked for
  correctness with this flag.
  Logstash can read multiple config files from a directory. If you combine this
  flag with `--debug`, Logstash will log the combined config file, annotating the
  individual config blocks with the source file it came from.

-h, --help
  Print help
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