dmesg.py

#!/usr/bin/python3

__doc__ = """

Small utility script that will log the contents output by dmesg to a file.

./dmesg.py [append]

The option append set to append will make the script only append to
/var/log/dmesg.log, without it, or set to loop, the script will also rotate
and compress log files. Option append set to loop, makes the script loop
forever, appending.

"""

import glob, os, sys, time

def sorting(a):
  return int(a.split('.')[2])

def increment_filename(filename):
  number = int(filename.split('.')[2])
  number += 1
  return "/var/log/dmesg.log." + str(number) + ".gz"

append = loop = False

try:
  append = sys.argv[1]
  if append == 'loop':
    loop = True
    append = True
  elif append == 'append':
    append = True
except IndexError:
  pass

if not append or loop:
  dmesg_files = glob.glob("/var/log/dmesg.log.*.gz")
  if len(dmesg_files) > 0:
    dmesg_files = sorted(dmesg_files, key=sorting, reverse=True)
    print(dmesg_files)
    for filename in dmesg_files:
      os.rename(filename, increment_filename(filename))
  dmesg_file_old = glob.glob("/var/log/dmesg.log.0")
  if dmesg_file_old:
    os.rename("/var/log/dmesg.log.0", "/var/log/dmesg.log.1")
    os.system("gzip -9 /var/log/dmesg.log.1")
  dmesg_file = glob.glob("/var/log/dmesg.log")
  if dmesg_file:
    os.rename("/var/log/dmesg.log", "/var/log/dmesg.log.0")
while True:
  os.system("dmesg -cHPT >> /var/log/dmesg.log 2>&1")
  os.system("/bin/sync")
  if not loop: break
  time.sleep(5)