Shell Programming and Scripting

awk -v ft=$ftmp '/>/{x=ft"."++i; next} {print > x;}' p.dat

cat p.dat
  1
  1
  1
>
  2 
  2
  2
>
  3 
  3 
  3
>
  4
  4
  4
>
  5
  5
  5
>
  6
  6
  6

awk -v ft=$ftmp '{i=i++%3+1;  i2=(i==1)?i2+1:i2; print > ft"."i2"."i}' RS="\n>\n"  p.dat

#!/bin/ksh
cnt=3
Usage="Usage: $(basename $0) [-n cnt] file..."
# Split input file(s) into files named file.X.Y where X and Y reset to 1
# and 1, respectively, for each file operand.  A new file is created
# when a line in an input file starts with a <greater-than> character
# (">").  Lines starting with a <greater-than> character are not
# included in any of the output files, but all other lines are copied 
# unchanged into the corresponding output file.  When a new file is
# created, Y is incremented until it exceeds cnt (which defaults to 3 if
# the -n option is not given on the command line.  When Y exceeds cnt, X
# is incremented and Y is reset to 1.
while getopts n: opt
do      case $opt in
        (n)     cnt="$OPTARG";;
        (?)     echo "$Usage" >&2
                exit 1
        esac
done
shift $(($OPTIND - 1))
if [ $# -lt 1 ]
then    echo "$(basename $0): At least one file operand is required." >&2
        echo "$Usage" >&2
        exit 2
fi
awk -v cnt=$cnt '
FNR == 1 {
        # This is the first record of a new input file.
        # If this is not the first input file, close the last output file for
        # the previous input file.
        if(NR != FNR) close(fn)
        # Create output filename based on input filename.
        x = y = 1
        fn = FILENAME "." x "." y
}
/^>/ {  # Close current output file
        close(fn)
        if(y == cnt) {
                y = 1
                x++
        } else  y++
        fn = FILENAME "." x "." y
        next
}
{       print > fn
}' "$@"