Simple implementation of the tail command in Python

tail.py

'''
Basic tail command implementation
Usage:

tail.py filename numlines

'''

import sys
import linecache

if len(sys.argv) !=3:
    print 'Usage: tail.py <file> <nlines>'
    sys.exit(1)

# filename and number of lines requested
fname, nlines = sys.argv[1:]
nlines = int(nlines)

# count the total number of lines
tot_lines = len(open(fname).readlines())

# use line cache module to read the lines
for i in range(tot_lines - nlines + 1, tot_lines+1):
    print linecache.getline(sys.argv[1],i),

tail_2.py

""" This is a more efficient version, since it does not read the entire
file
"""

import sys
import os

bufsize = 8192

lines = int(sys.argv[1])
fname = sys.argv[2]
fsize = os.stat(fname).st_size

iter = 0
with open(sys.argv[2]) as f:
    if bufsize > fsize:
        bufsize = fsize-1
    data = []
    while True:
        iter +=1
        f.seek(fsize-bufsize*iter)
        data.extend(f.readlines())
        if len(data) >= lines or f.tell() == 0:
            print(''.join(data[-lines:]))
            break

This is great, but you don't need the # -*- coding: utf-8 -*- line in Python 3

Python 3.8 asyncio version,

#! /usr/bin/env python
# -*- coding: utf-8 -*-
...

@therumbler TIL, thanks! I've been using the same "new file" template for years. Time to update!

Tail in Lua: https://gist.github.com/blasti/a1f2fd90f0f6933fe5583ea6777a374a