I had a problem with my iMac today, everytime I tried to login it would get as far as showing me my desktop and the dock and then it would crash back to the login screen.

I found the following in the /var/log/system.log:

crashdump: Crash report written to: /Users/robin/Library/Logs/CrashReporter/loginwindow.crash.log

Having a look inside that file didnt really tell me much. So I tried to find the Darwin equivelant of strace or truss. There doesnt seem to be one, however I found fs_usage. This program will log all filesystem access after you run it, until you tell it to quit.

To debug this way you need to ssh into the problem mac from another machine, and on the command line (as root) run:

# fs_usage -w

If you use a bash shell you can capture the output to a file with:

# fs_usage -w > fs_usage.out 2>&1

Then try to login again, of course it will fail again, but this time we have captured all file system access in the fs_usage.out file or in our scroll back buffer.

You probably want to tell fs_usage to quit before you continure, press Ctrl-C.

Looking through this file I searched up from the bottom for the last line containing my username. I found this:

/Users/robin/Library/Preferences/com.apple.scheduler.plist

I went to have a look in that file. All .plist files in OsX are xml configuration files, but this one didnt containt xml it contained binary junk.

I moved this file to a different file name and tried to login again.

All working, thank god we have unix underneath!

Ells found this looks like it is very useful when debugging server side scripts and webserver problems.

Fond this page, annoying banner ads but quite good javascript info.

Found a nice large services file here (Long since dead).

I can never find the entity I’m looking for, but then i found this; HTML 4.0 Entities

Found Espresso Blog, nice osX to moveable type posting ute.

Found this a page (long since broken!). Which is useful for adding a serial console at boot. After the change to the config file you do not need to re-run grub-install because it reads the config file at boot.

should turn up on the useful.things/osx/

Sun machines with solaris have a nasty tendancy to halt when you remove the keyboard or the serial cable while they are running.

This behaviour can be stopped by editing /etc/default/kbd and changing the value of KEYBOARD_ABORT to disable.