Shell Programming and Scripting

awk -v head="$(head -1 file)" '
function nf() {
        x = sprintf("F%02d", ++ofc)
        print head >x
        cnt = 0
}
.................
.................
.................
' file

BEGIN {lpf=5000} NR==1 {head = $0; nf()}

#!/bin/ksh
IAm=${0##*/}
if [ $# -gt 2 ] || [ $# -lt 1 ]
then    printf "Usage: %s file [lines_per_file]\n" "$IAm" >&2
        exit 1
fi
file=${1}
lpf=${2:-5000}  # Set lines to be included in each output file.
awk -v lpf="${lpf}" '
function nf(fn) {
        x = sprintf("F%02d", fn)
}
NR == 1 {
        # Save header from 1st line.
        h = $0
        next
}
NR > 2 {if(cnt == 0) {
                # Get next output file and add the header line.
                nf(++ofc)
                print h > x
                cnt = 2 # Reserve space for trailer line to be added later.
        }
        # Add previous input line to current output file.
        print last > x
        cnt++
}
{       # Save current line.  Do not print it yet so we can skip the last line.
        # When we hit EOF, last will contain the trailer to be added to all of
        # the output files.
        last = $0
}
cnt >= lpf && ! /^ *3/ {
        # If we have a full file and current line does not start with a 3,
        # close current output file and clear output line count.
        close(x)
        cnt = 0
}
END {   # Add trailer line to all output files.
        while(ofc) {
                nf(ofc--)
                print last >> x
                close(x)
        }
}' "$file"