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#!/usr/bin/env python
# -*- coding: utf-8-with-signature-unix; fill-column: 77 -*-
# -*- indent-tabs-mode: nil -*-
# This file is part of pyutil; see README.rst for licensing terms.
import os, sys
from random import randrange
import argparse
def main():
CHUNKSIZE=2**20
parser = argparse.ArgumentParser(prog="randfile", description="Create a file of pseudorandom bytes (not cryptographically secure).")
parser.add_argument('-b', '--num-bytes', help="how many bytes to write per output file (default 20)", type=int, metavar="BYTES", default=20)
parser.add_argument('-f', '--output-file-prefix', help="prefix of the name of the output file to create and fill with random bytes (default \"randfile\"", metavar="OUTFILEPRE", default="randfile")
parser.add_argument('-n', '--num-files', help="how many files to write (default 1)", type=int, metavar="FILES", default=1)
parser.add_argument('-F', '--force', help='overwrite any file already present', action='store_true')
parser.add_argument('-p', '--progress', help='write an "x" for every file completed and a "." for every %d bytes' % CHUNKSIZE, action='store_true')
args = parser.parse_args()
for i in xrange(args.num_files):
bytesleft = args.num_bytes
outputfname = args.output_file_prefix + "." + str(i)
if args.force:
f = open(outputfname, "wb")
else:
flags = os.O_WRONLY|os.O_CREAT|os.O_EXCL | (hasattr(os, 'O_BINARY') and os.O_BINARY)
fd = os.open(outputfname, flags)
f = os.fdopen(fd, "wb")
zs = [0]*CHUNKSIZE
ts = [256]*CHUNKSIZE
while bytesleft >= CHUNKSIZE:
f.write(''.join(map(chr, map(randrange, zs, ts))))
bytesleft -= CHUNKSIZE
if args.progress:
sys.stdout.write(".") ; sys.stdout.flush()
zs = [0]*bytesleft
ts = [256]*bytesleft
f.write(''.join(map(chr, map(randrange, zs, ts))))
if args.progress:
sys.stdout.write("x") ; sys.stdout.flush()
if __name__ == "__main__":
main()
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