sed and awk: editing and fields of a stream

Articles

• Glob patterns and brace expansion — Shell substitutions — * ? [] {} — and how they differ from regular expressions.
• cut — cut fields out of lines — The cut command takes fields out of every line by a delimiter (-d and -f) or characters by position (-c).
• sed and awk — editing and fields in a text stream — sed edits and deletes lines by pattern, awk splits lines into fields and computes over them, line by line.
• Regular expressions — patterns for grep, sed and awk — A pattern that many strings match: characters, classes like [0-9], repeats * and +, anchors ^ and $. grep searches lines by it, sed replaces text, awk selects lines.
• diff and patch — comparing and applying changes — Comparing files and applying patches: diff two configs, see what changed, apply a patch.