在Linux / bash下拆分文件及其行

I have a rather large file (150 million lines of 10 chars). I need to split it in 150 files of 2 million lines, with each output line being alternatively the first 5 characters or the last 5 characters of the source line. I could do this in Perl rather quickly, but I was wondering if there was an easy solution using bash. Any ideas?I have a rather large file (150 million lines o