If a user is splitting a large file into pieces only to use several of them, it will be efficient to just specify the indexes of files to output.
Take an extreme case for example. "a_large_file" has 12823371193 lines. "csplit a_large_file 823371193 823371293" will have three output files: xx00 with 823371192 lines, xx01 with 100 lines, and xx02 with the rest. If a user is only interested in xx01, it will be desirable to do "csplit a_large_file 823371193 823371293 -o 1."
