shell sed替换文本

code

macname@localhost Desktop % cat content 
fox jumps over the lazy dog. 
fox jumps over the lazy dog. 
fox jumps over the lazy dog. 
fox jumps over the lazy dog.
macname@localhost Desktop % 
macname@localhost Desktop % sed 's/dog/cat/' content
fox jumps over the lazy cat. 
fox jumps over the lazy cat. 
fox jumps over the lazy cat. 
fox jumps over the lazy cat.
macname@localhost Desktop % 
macname@localhost Desktop % cat content 
fox jumps over the lazy dog. 
fox jumps over the lazy dog. 
fox jumps over the lazy dog. 
fox jumps over the lazy dog.
macname@localhost Desktop %