sed

sed: stream editor
use it to filter and modify text, e.g. in-place within text-files.

example file, tonics.txt:

Delicious tonic combinations:
1. Ginger, Carrot, Apple
2. Orange, Ginger, Lime
3. Ginger, Pineapple, Blood orange
4. Whey protein, Banana, Ginger
5. Oat milk, Ginger

example: replace Ginger with Lemon from tonics.txt, without overwriting the file
sed 's/Ginger/Lemon/' tonics.txt

example: replace file inplace:
sed -i 's/Ginger/Lemon/' tonics.txt

delete word
sed 's/Ginger//' tonics.txt

delimiters

if one of the characters you want to replace is a forward slash, /,
use a different delimiter.

example:
find /etc -type f > paths.txt

cat paths.txt

deletion:
sed 's./etc..' paths.txt

replacement:
sed 's./etc.something-else.' paths.txt

example: echo "Code Vault" | sed 's/Vault/Hive/'