Split file by vector of line numbers

Question

I have a large file, about 10GB. I have a vector of line numbers which I would like to use to split the file. Ideally I would like to accomplish this using command-line utilitie

Answer 1

Very slightly different from James's and kvantour's solutions: passing the vector to awk as a "file"

vec="2 5"

awk '
    NR == FNR {nr[$1]; next}
    FNR == 1 {filenum = 1; f = FILENAME "." filenum}
    FNR in nr {
        close(f)
        f = FILENAME "." ++filenum
    }
    {print > f}
' <(printf "%s\n" $vec) file

$ ls -l file file.*
-rw-r--r-- 1 glenn glenn 48 Jul 17 10:02 file
-rw-r--r-- 1 glenn glenn  7 Jul 17 10:09 file.1
-rw-r--r-- 1 glenn glenn 23 Jul 17 10:09 file.2
-rw-r--r-- 1 glenn glenn 18 Jul 17 10:09 file.3