文字列の一部を置き換えする(sed)

#!/bin/sh
#str_replace.sh

text="The quick brown fox jumps over the lazy fox."
echo $text | sed 's/fox/DOG/'
echo $text | sed 's/fox/DOG/g'
#oで始まる単語をafterに変更する
echo $text | sed 's/\<o[^ ]*/after/'

$ ./str_replace.sh 
The quick brown DOG jumps over the lazy fox.
The quick brown DOG jumps over the lazy DOG.
The quick brown fox jumps after the lazy fox.