filter each line of linux bash output by regexp [closed]

Question

I want to filter the output of arbitrary output e.g. cat or objdump to only display lines which contain "pattern".

Is there a one-liner UNIX/Linux command to do this?

e.g. cat filepath | xargs grep 'pattern' -l is not working for me

Answer 1

cat file | grep pattern 

You could also just use grep pattern file if it's a static file.

Answer 2

Better to use grep -e or egrep(this allows for extended regular expressions). Then you can do more robust things with regex:

 cat my_phonebook | egrep "[0-9]{10}" 

To show all 10 digit phone numbers in a file.

If you toss in a -o, only the numbers get returned (instead of the before and after content on the line).