Question

I need to replace pattern matching line with yet another string.

Example

line1
line2
the serial port is ttyS0
line4

I need to replace line containing ttyS0 as

line1
line2
You have to use usb interface
line4

How can I do that in sed (or grep)

I tried sed 's/ttyS0/You have to use usb interface/' myfile . But it replaces only the matching words from the line. I want to replace the complete line.

Answer 1

Like this:

sed 's/.*ttyS0.*/You have to use usb interface/' myfile