i think your question is distro-specific, or at least it differs between sysvinit and systemd - which is the two main technique of starting up. For Fedora Core 17 beta (my system), it is running systemd: http://lwn.net/Articles/458789/ and here it shows all the good points about systemd: http://0pointer.de/blog/projects/why.html (noting the shutdown features if u are focusing on the shutdown part). more info: https://fedoraproject.org/wiki/Systemd [PDF] Beyond Init: systemd - LinuxKongress 2010 www.linux-kongress.org/2010/slides/systemd-poettering.pdf But as mentioned in document above, /dev/initctl is still supported, which is the traditional means of shutting down. In Ubuntu (which uses sysvinit, and shutting down is via /dev/initctl), u can get the source code for poweroff via: "apt-get source upstart" and then start navigating through the source code. Within util/shutdown.c you can see following: * struct request: * * This is the structure passed across /dev/initctl. **/ struct request { int magic; int cmd; int runlevel; int sleeptime; char data[368]; }; /** * sysvinit_shutdown: * * Attempt to shutdown a running sysvinit /sbin/init using its /dev/initctl * socket. **/ static void sysvinit_shutdown (void) { struct sigaction act; struct request request; int fd; /* Fill in the magic values */ memset (&request, 0, sizeof (request)); request.magic = 0x03091969; request.sleeptime = 5; request.cmd = 1; /* Select a runlevel based on the event name */ There goes all the magic....or some part of it.... On Mon, May 14, 2012 at 7:31 PM, Asutosh Das <das.asutosh@gmail.com> wrote:
Hi List I have a query about the linux shutdown or reboot process.
Please can you let me know if the below sequence is correct:
When reboot command is given on the shell:
1. all user-space process is frozen (by sending some signal ?? ) 2. all file-systems are remounted as read-only - (sysrq handler does this ?? ) 3. all drivers, whose shutdown handlers have been defined, are called in the reverse order in which these drivers were initialized.
I am not sure what happens after this.
TIA.
-- Thanks & Regards ~/asd
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