sed - Stream Editor with Interactive Preview

The sed module extends the classic stream editor by adding an interactive preview mode. Users can test their regex substitutions and see context differences (ctrl-s) in real-time before modifying files.

When to Activate

• When the user wants to perform text search and replace operations.
• When an interactive preview of regex effects is needed to avoid errors.
• When performing bulk line deletions or insertions in files.
• When using extended regular expressions for complex text manipulation.

Core Principles & Rules

• Preview First: Encourage using the --fzfapp mode to verify changes visually.
• Context Differences: Use ctrl-s within the interactive app to view diffs.
• In-place Safety: Use -i carefully, preferably with a backup suffix.

Patterns & Examples

Interactive Preview

# Interactively test and preview regex changes on a file
x sed --fzfapp test.txt

Basic Substitution

# Replace 'world' with 'universe' in a piped string
echo "hello world" | x sed 's/world/universe/'

Global Replace

# Replace all occurrences of 'foo' with 'bar' in a file
x sed 's/foo/bar/g' file.txt

Checklist

• Confirm if the user needs an interactive preview or direct execution.
• Verify the regex pattern for search and replace.
• Check if the file should be modified in-place or output to stdout.