I need help from anyone out there. I have three files (one about 400 lines, one about 13000 lines and one about 13450 lines). The two smaller files are included somewhere within the larger file, however I am trying to isolate the 50 lines that do not appear in either of the first two files. I've tried a combination of joins and cmps but I can't seem to figure out how to isolate the 50 lines that don't appear in the other two files. Can any of you help? thanks!

I would think sort and diff should do it: sort file1 > file1s sort file2 file3 > file23s diff file1s file23s |   grep '^\<' |   cut -c3- Or, for this awk solution, file2 and file3 should be the smallest 2 files since they have to fit in a memory array: awk 'BEGIN{ while ((getline < "file2") > 0)    list[$0] = 1 while ((getline < "file3") > 0)    list[$0] = 1} !list[$0]' file1 > file1.only