Can I use a Terminal command to switch to a specific space in OS X 10.6?

If you have assigned keyboard shortcuts for switching between Spaces in System Preferences, you can trigger them using AppleScript:

osascript -e 'tell application "System Events" to key code 124 using control down'

This will effectively press Control-Right. Left is 123, Up is 126, and Down is 125.

These are the key codes for the number keys:

1 18
2 19
3 20
4 21
5 23
6 22
7 26
8 28
9 25
0 29

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Just assign an alias to that osascript call or wrap it in a shell function.