Python script that takes lines of text containing byte hex values, and appends a printable representation of the bytes to each line. It's similar to xxd, but it takes already dumped bytes instead of the original binary data. Example: "70 79 74 68 6f 6e" -> "70 79 74 68 6f 6e python"

bytes2ascii.py

#!/usr/bin/env python

import fileinput
import re

# pattern to match lines of hex byte values
PATTERN = re.compile("^[a-zA-Z0-9]{1,2}( [a-zA-Z0-9]{1,2})*$")

# margin between bytes and text
MARGIN = 2
# expected number of bytes for which the text is aligned
MINBYTES = 16
# expected width of a line of bytes
MINLINELEN = MINBYTES * 3 - 1

# translate hex byte string to printable character
def translate(bytestr):
  value = int(bytestr, 16)
  if 32 <= value <= 127:
    return chr(value)
  else:
    return "."

for line in fileinput.input():
  # eat newline
  line = line.strip()
  if PATTERN.match(line):
    # translate the bytes
    text = "".join(map(translate, line.split(" ")))
    # calculate the margin
    linelen = max(MINLINELEN, len(line))
    # append to the original line
    line += (" " * (linelen - len(line) + MARGIN))
    line += text
  print line