Mac OS X log files
Mac OS X logs warnings and error messages, among other things, to various text files. The events in the logs will have a date and time stamp. The contents of these log files can help narrow down when, where, and why problems occur, so they are an important troubleshooting aid that were not available on Mac OS 9.
System log
The main system log is found simply by opening the Console application. It is found in the "Utilities" folder inside the computer's "Applications" folder.
Printing logs
The CUPS printing subsystem in Mac OS X 10.2 and later keeps its logs in the following location:
/var/log/cups/error_log
Crash logs
When individual applications like Microsoft Word or Apple Mail crash, the operating system will create a crash log. These log files are organized by application and stored in:
~/Library/Logs/
The crash logs can be opened in the Console utility, or displayed in the Apple System Profiler program.
Crash logs may be useful to technical staff. They can be invaluable to vendors wishing to fix problems in programs, as well.
Kernel panic log
A kernel panic is a very rare event in Mac OS X. In Mac OS X 10.2, you will see the following information on your screen if you have a kernel panic:
If your computer is suffering from a repeatable kernel panic that forces you to reboot the system, an examination of the kernel panic log is in order. You definitely should seek to fix the problem, because a regular kernel panic is most certainly not normal on a Mac OS X system.
The majority of the kernel panic problems we have seen have been traceable to the following sources:
- bad memory (RAM) installed in the computer -- focus on RAM that was added after you purchased the computer
- add-on devices that plug into the computer -- focus on those that require their own software drivers, such as card readers for digital cameras, scanners, printers, PCI cards, and so on
- too many devices connected to or installed in the computer -- potentially leading to conflicts, especially if the devices draw too much power (collectively or individually), which may be avoided by using quality powered USB or FireWire hubs, or removing unnecessary cards from the PCI bus
There is no hard and fast rule we have found for kernel panics -- although replacing RAM has been the highest probability fix we have seen so far -- so take the above list as a set of guidelines to begin your troubleshooting.
The Console application can open the kernel panic log. The Apple System Profiler will also display the kernel panic log. Mac OS X 10.2 and later save the kernel panic log at:
/Library/Logs/panic.log
If you do not have a file named panic.log in this location, you may be running Mac OS X 10.1.x (which does not save panic logs), the file may have been deleted, or you may not have had a kernel panic at all.
For an in-depth description of kernel panics, refer to Apple Technical Note TN2063: Understanding and Debugging Kernel Panics.
