rare

Rare is a fast, realtime regex-extraction, and aggregation into common formats such as histograms, numerical summaries, tables, and more!

Rare is composed of three parts in the pipeline:

1. Extraction (Matching)
2. Expression Building
3. Aggregation

Extraction (Matching)

Extraction is denoted with -m (match) and is the process of reading a line in a file or set of files and parsing it with a regular expression into the match-groups denoted by the regex.

If the regex doesn't match, the line is discarded (a non-match)

These match groups are then fed into the next stage, the expression.

Read more at:

• extractor

Expressions

Expressions -e take the match groups, and other pieces of information, and build a string-based key. The match groups can be operated on by helpers to build the string-key (eg arithmatic, json parsing, simple logic).

The result of this key will act as the key for the aggregation stage.

Optional ignore expression(s) can be supplied with -i which will cause the match to be ignored if the expression evaluates to be truthy.

Read more at:

• expressions

Aggregation

The last stage is the aggregation and realtime presentation. This takes the key built in the expression stage and uses it to aggregate on. Different aggregators display the data in different ways.

Aggregator types:

• filter is grep-like, in that each line will be processed and the extracted key will be output directly to stdout
• histogram will count instances of the extracted key
• table will count the key in 2 dimensions
• bargraph will create either a stacked or non-stacked bargraph based on 2 dimensions
• analyze will use the key as a numeric value and compute mean/median/mode/stddev/percentiles

For more details, see aggregators, run rare --help for usage, or look at some examples