Jeremy
Depending on what you are trying to accomplish probably the best solution is to send the log messages to a syslog server (the command is logging and have the syslog server put the messages into a file.
In IOS you can send messages to several places: by default messages are sent to the console, and you can also send them to logging buffered (these messages are maintained in memory on the router - you access them by show logging - they are lost if the router reboots) and you can also send messages to a syslog server and you can send messages to monitor (you get these by terminal monitor if you are telnetted to the router).
If you want to use the messages from show logging, it is possible to copy and paste them into a text file which you could then process as you wish.
HTH
Rick
HTH
Rick