show file content like Linux `cat` command but only show specified line

cat_line.py

#!/usr/bin/python
# -*- coding: utf-8 -*-
from __future__ import print_function

import argparse
import os
import linecache
import sys


description= '''show file content like Linux `cat` command but only show specified lines'''
parser = argparse.ArgumentParser(description=description)

parser.add_argument('-b', '--begin', type=int, help='begin range of lines (default: 1)')
parser.add_argument('-e', '--end', type=int, help='end range of lines (default: lines count of file)')
parser.add_argument('file', type=str, nargs='?', help='the file path')

args = parser.parse_args()
begin = getattr(args, 'begin', None)
end = getattr(args, 'end', None)
_file = getattr(args, 'file', None)

c_error = '\x1b[6;37;41m'
c_end = '\x1b[0m'
c_warning = '\x1b[7;30;43m'

def file_lines(path, begin, end=None):
    lines = []
    # way 1
    i = begin
    '''
    with open(path) as f:
        for index, line in enumerate(f):
            if begin <= index + 1 <= end:
                if i <= end:
                    lines.append(line)
                    i += 1
                else:
                    break
    '''
    # way 2
    #'''
    while True:
        line = linecache.getline(path, i)
        if isinstance(end, int):
            if i > end:
                break
        else:
            if line == '':
                break
        i += 1
        lines.append(line)
    #'''
    return lines

if _file is None:
    parser.print_help()
else:
    if os.path.exists(_file):
        if begin is None:
            begin = 1
        if isinstance(end, int):
            if begin > end:
                print('Error: {0}`begin` is greater than `end`{1}'.format(c_error, c_end))
                sys.exit(0)
        lines = file_lines(_file, begin, end)
        print(''.join(lines), end='')
    else:
        print('Error: {0}file `{1}` not exist{2}'.format(c_error, _file, c_end))
        print('{0}{1}{2}'.format(c_warning, '=' * 60, c_end))
        parser.print_help()

usage example in terminal:

# assign execution permission
chmod a+x ./cat_line.py

• example 1

  ./cat_line.py /usr/share/mime/types -b 3 -e 5
  # will print from line 3 to line 5 (line: 3, 4, 5)

  output:

  application/atom+xml
  application/dicom
  application/ecmascript
  

• example 2

  ./cat_line.py /usr/share/mime/types -b 743
  # will print from line 743 to the left all lines of file

  output:

  x-content/video-svcd
  x-content/video-vcd
  x-content/win32-software
  x-epoc/x-sisx-app