head and tail a stream

headtail

#!/usr/bin/env python

import argparse
import sys
import collections

parser = argparse.ArgumentParser(description='Show the first 10, and last 10 lines of a file.')
parser.add_argument('infile', nargs='?', default=sys.stdin,
                    help='Input file. Defauts to stdin if not provided.')
parser.add_argument('outfile', nargs='?', default=sys.stdout,
                    help='Output file. Defauts to stdout if not provided.')
parser.add_argument('--head-lines', '-n', type=int, default=10,
                    help='Number of head lines to display.')
parser.add_argument('--tail-lines', '-t', type=int, default=10,
                    help='Number of tail lines to display.')
args = parser.parse_args()

tail_lines = collections.deque([], args.tail_lines)
for i, l in enumerate(args.infile.readlines()):
    if i < args.head_lines:
        args.outfile.writelines([l])
    else:
        tail_lines.append(l)
args.outfile.writelines(tail_lines)