I\'m not sure if it was asked, but I couldn\'t find anything like this.
My program uses a simple .txt file for log purposes, It just creates/opens a file and appends
Look at popular logfiles like /var/log/syslog on Unix to get ideas:
MMM DD HH:MM:SS hostname process[pid]: message
Example out of my syslog:
May 11 12:58:39 raphaelm anacron[1086]: Normal exit (1 job run)
But to give you the perfect answer we'd need more information about what you are logging, how much and how you want to read the logs.
If this is a program, you might investigate apache logging libraries (http://logging.apache.org/) Out of the box, they'll give you a decent logging format out of the box. They're also customizable, so you can simplify your parsing job.
If this is a script, see some of the other answers.