The sed (stream editor) command combines search and transform in one command. You can match patterns in text using RegEx like grep. But instead of highlighting matches, it is used to transform matches.

Create a file for demonstration:

cat > unix-philosophy.txt << EOF
Write programs that do one thing and do it well.
Write programs to work together.
Write programs to handle text streams, because that is a universal interface.
EOF

Use sed to change the text.

cat unix-philosophy.txt | sed 's/Write/Vibe code/'

It’s a joke

Or we can let sed read the file directly.

sed 's/Write/Vibe code/' unix-philosophy.txt

Output to a file.

sed 's/Write/Vibe code/' unix-philosophy.txt > mcp-manifest.txt

Or change the file directly.

sed -i 's/text/json/' mcp-manifest.txt

We can make it quite when a match is found.

sed '/work/q' unix-philosophy.txt

Delete a word.

sed 's/well//' mcp-manifest.txt

Or delete a line.

sed '/well/d' mcp-manifest.txt

Some transforms can be combined.

sed 's/Write/Vibe code/ ; /well/d' unix-philosophy.txt

Text can be appended.

sed 'aIt''s a joke' mcp-manifest.txt

You can learn more about sed here.