shell - Insert text before a certain line using Bash

Question

How can I insert a set of lines (about 5) into a file at the first place a string is found?

For example:

BestAnimals.txt

dog
cat
dolphin
cat

$ "Insert giraffe to BestAnimals.txt before cat" > NewBestAnimals.txt

NewBestAnimals.txt

dog
giraffe 
cat
dolphin
cat

Answer 1

If using gnu sed:

$ cat animals
dog
cat
dolphin
cat

$ sed  "/cat/ { N; s/cat
/giraffe
&/ }" animals
dog
giraffe
cat
dolphin
cat

1. match a line with (/cat/)
2. continue on next line (N)
3. substitute the matched pattern with the insertion and the matched string, where & represent the matched string.