grep regular expression returns full line

Question

Im trying to print everything after a keyword using grep but the command returns the whole line. Im using the following:

grep -P (\skeyword\s)(.*)

an example line is:

abcdefg         keyword   hello, how are you.

The result should be hello, how are you but instead it gives the full line. Am I doing something wrong here?

Answer 1

You need to use -o ( only matching ) parameter and \\K ( discards the previously matched characters ) or a positive lookbehind.

grep -oP '\skeyword\s+\K.*' file

\\K keeps the text matched so far out of the overall regex match. \\s+ matches one or more space characters.

Example:

$ echo 'abcdefg         keyword   hello, how are you.' | grep -oP '\skeyword\s+\K.*'
hello, how are you.

Answer 2

By default, Grep prints lines that match. To print only matching expressions try the '-o' option.