If you have problems with your PC locking or going to sleep, caffeine will keep it awake. It works by simulating a keypress once every 59 seconds, so your machine thinks you're still working at the keyboard, so won't lock the screen or activate the screensaver.

The icon is shown above - it's the leftmost one in the task tray, and this is all you see. Double-clicking the icon empties the coffee pot (that's what the icon is) and temporarily disables the program. Double-clicking it again refills the pot, and will keep your machine awake.

By default the app starts enabled, and works every 59 seconds. There are seven command line switches you can use to alter this behaviour:

• xx - where xx is a number which sets the number of seconds between simulated keypresses. This must be the first text on the commandline
• -startoff - application starts disabled.
• -exitafter:xx - application will terminate after xx minutes
• -activefor:xx - application will become inactive after xx minutes
• -appexit - terminates current running instance of application
• -appon - makes the current running instance of the application active
• -appoff - makes the current running instance of the application inactive
• -replace - closes the current running instance, replacing it
• -noicon - does not show a task tray icon
• -useshift - simulate the shift key instead of the right context-menu key

Windows 98: Caffeine works by simulating right context-menu key down and up events every 59 seconds.
Windows 2000/XP: Caffeine works by simulating a right context-menu up event every 59 seconds.

Of all the key presses available, right context-menu is probably the least intrusive, and least likely to interfere with your work.

Versions

v1.2 - 15th March 08
Command line switches added to set the interval and to start disabled

v1.3 - 3rd February 09
Command line switches added to terminate the app after x minutes, disable the app after x minutes, and enable or disable the currently running instance of the app

v1.35 - 28th May 09
Simulated keypress changed from shift to the right context menu key (at the suggestion of Kevin Kleinfelter) as this is likely to be less intrusive.

v1.4 - 18th July 09
New command line options:

• -replace
• -noicon
• -useshift

caffeine.zip (13k)