I have two files: fileA: date >> /root/kvno.out kvno serverXXX\$ >> /root/kvno.out fileB: foobar I need to create a new file, fileC, with the same contents as fileA, except with the string XXX being replaced with the contents of fileB: date >> /root/kvno.out kvno serverfoobar\$ >> /root/kvno.out I'd like to do this using sed. I tried some of the examples I found but I only get the contents of fileB in fileC.