Produce coloured log output in adb logcat style

This script is intended to be used for producing coloured logfile output, in similar fashion to adb logcat, which highlights each log line with a different colour, based on its loglevel.

The script looks for log lines that start with <timestamp> <name> <loglevel>, where the log level must be one of DEBUG, INFO, WARNING, ERROR or CRITICAL, written in capital letters, and colours the line accordingly. Any other lines are left untouched (default terminal colour). The intended logfile output should be produced by Python, e.g.:

import logging
logformat = logging.Formatter("%(asctime)s %(name)s %(levelname)s %(message)s")

The script can be used as a tail -f replacement. If no input is provided on stdin, it will by default follow the given file:

user@server ~# colortail /var/log/someservice.log

The script will show the last 80 lines of the file and follow it, or keep trying if the file is not yet accessible. I.e. same as tail -n 80 -F.

Or it can accept piped input:

user@server ~# colortail < /var/log/someservice.log
user@server ~# cat somefile.log | colortail

Samples

A logfile with <timestamp> <additional> <producer name> <log level> <message>:

A logfile with <timestamp> <producer name> <log level> <thread> <message>, showing all possible log levels and their colours: