перенаправить стандартный выход
$ ./command file1 file2 file3 | sed "s/^/Robot says: /"
stderr file2
Robot says: stdout file1
Robot says: stdout file3
Newbie
$ ./command file1 file2 file3 | sed "s/^/Robot says: /"
stderr file2
Robot says: stdout file1
Robot says: stdout file3# Redirect to stdout, so it comes through the pipe
$ echo "no changes" >&1 | sed "s/no/some/"
some changes
# Redirect to stderr, so it does not come through
$ echo "no changes" >&2 | sed "s/no/some/"
no changes