How to split a file and keep the first line in each of the pieces?

Question

Given: One big text-data file (e.g. CSV format) with a \'special\' first line (e.g., field names).

Wanted: An equivalent of the cor

Answer 1

You can use [mg]awk:

awk 'NR==1{
        header=$0; 
        count=1; 
        print header > "x_" count; 
        next 
     } 

     !( (NR-1) % 100){
        count++; 
        print header > "x_" count;
     } 
     {
        print $0 > "x_" count
     }' file

100 is the number of lines of each slice. It doesn't require temp files and can be put on a single line.