11. Text Processing, Regular Expressions, and JSON

This chapter turns Unix text tools into analysis tools for logs, command output, structured fields, and JSON data.

• Search: Find relevant records.

• Regex: Describe text patterns.

• Fields: Extract columns and delimited values.

• JSON: Use jq for structured output.

• Counts: Summarize repeated users, IPs, and events.

Chapter Video

Linux Crash Course - The grep Command (14:57) by Learn Linux TV

Hosted on YouTube; property of its original creator, embedded here for educational reference only.

Learning Objectives

By the end of this chapter, you will be able to:

1. Search and filter text with grep and regular expressions.

2. Extract fields with cut, awk, and related tools.

3. Transform text with sed and pipelines.

4. Parse JSON with jq.

5. Count and summarize repeated log events.

Chapter Flow

1. Searching & Filtering

2. Data Tools

3. awk, sed, and Regex

4. JSON with jq

Glossary

#	Term	Explanation
1	grep	Search tool for matching lines.
2	regular expression	Pattern language for text.
3	field	Part of a record separated by a delimiter.
4	delimiter	Character separating fields.
5	awk	Field-oriented text processor.
6	sed	Stream editor.
7	sort	Tool for ordering lines.
8	uniq	Tool for adjacent duplicate lines.
9	jq	Command-line JSON processor.
10	log parsing	Extracting useful records from logs.