python 文件分割 脚本

!/usr/bin/python

"""
################################################################################
split a file into a set of parts; join.py puts them back together;
this is a customizable version of the standard Unix split command-line
utility; because it is written in Python, it also works on Windows and
can be easily modified; because it exports a function, its logic can
also be imported and reused in other applications;
################################################################################
"""

import sys, os
kilobytes = 1024
megabytes = kilobytes * 1000
chunksize = int(1.4 * megabytes) # default: roughly a floppy

def split(fromfile, todir, chunksize=chunksize):
if not os.path.exists(todir): # caller handles errors
os.mkdir(todir) # make dir, read/write parts
else:
for fname in os.listdir(todir): # delete any existing files
os.remove(os.path.join(todir, fname))
partnum = 0
input = open(fromfile, 'rb') # use binary mode on Windows
while True: # eof=empty string from read
chunk = input.read(chunksize) # get next part <= chunksize
if not chunk: break
partnum += 1
filename = os.path.join(todir, ('part%04d' % partnum))
fileobj = open(filename, 'wb')
fileobj.write(chunk)
fileobj.close() # or simply open().write()
input.close()
assert partnum <= 9999 # join sort fails if 5 digits
return partnum

if name == 'main':
if len(sys.argv) == 2 and sys.argv[1] == '-help':
print('Use: split.py [file-to-split target-dir [chunksize]]')
else:
if len(sys.argv) < 3:
interactive = True
fromfile = input('File to be split? ') # input if clicked
todir = input('Directory to store part files? ')
else:
interactive = False
fromfile, todir = sys.argv[1:3] # args in cmdline
if len(sys.argv) == 4: chunksize = int(sys.argv[3])
absfrom, absto = map(os.path.abspath, [fromfile, todir])
print('Splitting', absfrom, 'to', absto, 'by', chunksize)

    try:
        parts = split(fromfile, todir, chunksize)
    except:
        print('Error during split:')
        print(sys.exc_info()[0], sys.exc_info()[1])
    else:
        print('Split finished:', parts, 'parts are in', absto)
    if interactive: input('Press Enter key') # pause if clicked