"interval cat": print every n-th character received on stdin

intcat.py

#!/usr/bin/env python

# intcat = interval cat:
#   Prints a human-readable character for every n-th character received on stdin.
#   Throughput depends heavily on n (faster for larger n).

n = 1000000

import sys, os

try:
    sys.stdout = os.fdopen(sys.stdout.fileno(), 'w', 0) # disable stdout buffering

    # string.printable, minus the newline characters
    printable = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ!"#$%&\'()*+,-./:;<=>?@[\\]^_`{|}~ '

    while True:
        s = sys.stdin.read(n)

        if s == '': # encountered EOF
            print
            sys.exit(0)

        ch = s[0]

        if not ch in printable:
            ch = printable[ord(ch)%len(printable)]

        sys.stdout.write(ch)

except KeyboardInterrupt:
    sys.exit(0)