How to dynamically pass values in awk

Question

I'm trying to split a csv file with too many rows into chunks of user defined no. of rows, using the following script using awk but its not generating any output, the file is created but its blank. Pls Can anyone point out what's missing...

# !/bin/bash
File=filename.csv
count=`awk 'END {print NR}' $File`
i=2
j=5000
k=$j
while [ $j -le $count ]
  do
    awk 'NR==1 {print $0}' $File > output"$i".csv
    awk 'NR==$i, NR==$j {print $0}' $File > output"$i".csv
    i=`expr $j + 1`
    j=`expr $i + $k`
    if [ $j -gt $count ]
      then
        j=$count
        k=`expr 0 - 1`
    elif [ $j -eq $count]
      then
        break
    fi
done

Answer 1

If you really want to use awk then how about

awk -v c=5000 '
    BEGIN{getline; head=$0; f = -1}
    {if (f != int((NR-2)/c)) {f+=1; fl=sprintf("%03d.csv", f); print head > fl}; print $0 > fl}
    ' filename.csv

As for your script.....

#!/bin/bash
File=filename.csv
count=$(awk 'END {print NR}' $File) # syntax
i=2
j=5000
k=$j
while [ $j -le $count ]
  do
    awk 'NR==1 {print $0}' $File > output"$i".csv
    # you cannot pass shell variables directly into awk, use -v
    # and append >> don't overwrite >
    awk -v st=$i -v fi=$j 'NR==st, NR==fi {print $0}' $File >> output"$i".csv 
    i=`expr $j + 1`
    j=`expr $i + $k`
    if [ $j -gt $count ]
      then
        j=$count
        k=-1
    elif [ $j -eq $count ] # needed a space before the ]
      then
        break
    fi
done