=== pm-utils === What is pm-utils? * Pm-utils provides simple shell command line tools to suspend and hibernate computer that can be used to run vendor, distribution, or user supplied scripts on suspend and resume. Why do we need it? * All the main distributions are re-implementing the same functionality to support common power management operations. pm-utils provides a standardized distribution agnostic layout and interface for common power management tasks, which frees software and hardware vendors from having to maintain distribution-specific suspend/resume functionality. * Suspend/resume functionality can be easily modified by installing files into the /etc/pm/sleep.d directory. These files, known as hooks, can perform specific tasks on suspend/resume, such as: - enabling and disabling standby LED's on laptop hardware - enabling suspend GUI's like suspend2 - re-enabling video - starting and stopping services that can't cope with suspending - re-syncing the time with ntp - removing and modprobing modules when needed - setting grub to be the default target for a hibernate-resume - other wacky things that need doing on specific systems How do hooks work? * You put an executable file in /etc/pm/sleep.d. When suspend or hibernate is called, several things happen: 1) The files in /etc/pm/config.d/* are evaluated in C sort order. These files can be provided by individual packages outside of pm-utils, and contain globally available configuration settings for pm-utils and the hooks. 2) Each of the hooks in /etc/pm/sleep.d/* are executed in C sort order, with a command line argument of either "suspend" or "hibernate". 3) The system suspends or hibernates. 4) Some event happens to wake the machine up 5) Each of /etc/pm/sleep.d/* are executed in reverse C sort order, with a command line argument of "resume" or "thaw". * For more detailed information on how hooks work and how to write one, read HOWTO.hooks . * For information on how to debug pm-utils, read README.debugging. That's it!