Text Processing

grep, sed, and awk are the "three text-processing swords": grep matches, sed rewrites in place, and awk extracts and aggregates by column. This reference collects each tool's highest-frequency forms and keeps the classic pipeline chain (grep to filter, sed to substitute, awk to summarize), for anyone who lives in logs, configs, and CSV.

An awk reference covering built-in variables such as NR and NF, conditionals and loops, per-column extraction and aggregation, string functions, and typical patterns for processing logs and CSV.

Batch-editing configs, redacting logs, and in-place replacement with a backup are sed's territory — the "rewrite" partner to awk's "aggregate". This reference covers substitution, deletion, insert/append, addressing by range, extended regex, and the -i in-place edit with -i.bak backup.