How to pass command output as multiple arguments to another command

Question

I want to pass each output from a command as multiple argument to a second command, e.g.:

grep "pattern" input

returns:

file1
file2
file3

and I want to copy these outputs, e.g:

cp file1  file1.bac
cp file2  file2.bac
cp file3  file3.bac

How can I do that in one go? Something like:

grep "pattern" input | cp $1  $1.bac

Answer 1

You can use xargs:

grep 'pattern' input | xargs -I% cp "%" "%.bac"

Answer 2

You can use $() to interpolate the output of a command. So, you could use kill -9 $(grep -hP '^\d+$' $(ls -lad /dir/*/pid | grep -P '/dir/\d+/pid' | awk '{ print $9 }')) if you wanted to.