examples/shutdown-1.0: an example of reboot which does not signal init
For one, my inits know nothing about the concept of "shutting down the system". Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko
parent
e09c426456
commit
c21dfaf836
30
examples/shutdown-1.0/README
Normal file
30
examples/shutdown-1.0/README
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# Replaces traditional overdesigned shutdown mechanism.
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#
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# No communication with init is necessary:
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# just ask all processes to exit.
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# Then unmount everything. Then reboot or power off.
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# Install /sbin/ symlinks named halt, reboot, poweroff
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# (and also possibly shutdown) to e.g.
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# /app/shutdown-1.0/script/shutdown:
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#
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ln -s /app/shutdown-1.0/script/shutdown /sbin/halt
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ln -s /app/shutdown-1.0/script/shutdown /sbin/reboot
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ln -s /app/shutdown-1.0/script/shutdown /sbin/poweroff
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#
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# shutdown spawns do_shutdown in new session, redirected to /dev/null,
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# tells user that shutdown is in progress, and sleeps
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# (for cosmetic reasons: do not confuse user by letting him
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# type more commands in this terminal).
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#
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# do_shutdown tries to switch to a VT console.
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# Then, (only if -r) it spawns a hardshutdown child, to reboot
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# unconditionally in 30 seconds if something later goes seriously bad.
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# Then it runs stop_tasks, writing to /var/log/reboot/YYYYMMDDhhmmss.log,
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# then it runs stop_storage.
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# Then it commands kernel to halt/reboot/poweroff, if requested.
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# Then it sleeps forever.
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#
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# Build the hardshutdown binary:
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#
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cd script && ./hardshutdown.make.sh
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54
examples/shutdown-1.0/script/do_shutdown
Executable file
54
examples/shutdown-1.0/script/do_shutdown
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#!/bin/sh
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# We are called with stdin/out/err = /dev/null
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resetgracetime=60
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logfile="/var/log/reboot/`date '+%Y%m%d%H%M%S'`.log"
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mkdir -p /var/log/reboot
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PATH=/sbin:/bin
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say() {
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printf "\r%s\n\r" "$*"
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}
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# Since there is a potential for various fuckups during umount,
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# we start delayed hard reboot here which will forcibly
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# reboot hung box in a remote datacenter a thousand miles away ;)
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if test "$1" = "-r"; then
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./hardshutdown -r "$resetgracetime" &
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fi
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# Now, (try to) switch away from X and open a console. I've seen reboots
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# hung on open("/dev/console"), therefore we do it _after_ hardshutdown
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exec >/dev/console 2>&1
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if test "$1" = "-r"; then
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say "* `date '+%H:%M:%S'` Scheduled hard reboot in $resetgracetime seconds"
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fi
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say "* `date '+%H:%M:%S'` Stopping tasks (see /var/log/reboot/* files)"
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# log reboot event to file. %Y%m%d%H%M%S: YYYYMMDDHHMMSS
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./stop_tasks >"$logfile" 2>&1
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# Dying X tends to leave us at semi-random vt. Try to fix that,
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# but if it doesn't work, proceed anyway.
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exec >/dev/null 2>&1
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chvt 1 & sleep 1
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exec >/dev/console 2>&1
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command -v ctrlaltdel >/dev/null && {
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say "* `date '+%H:%M:%S'` Setting Ctrl-Alt-Del to 'hard'"
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ctrlaltdel hard
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}
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say "* `date '+%H:%M:%S'` Stopping storage devices"
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# we can't log this: we are about to unmount everything!
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./stop_storage "$@"
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# If we have cmdline params, start hardshutdown with them
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test "$*" && ./hardshutdown "$@"
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# Just sleep endlessly...
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say "* `date '+%H:%M:%S'` You may now power off or press Ctrl-Alt-Del to reboot"
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while true; do sleep 32000; done
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168
examples/shutdown-1.0/script/hardshutdown.c
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168
examples/shutdown-1.0/script/hardshutdown.c
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/* Including <unistd.h> makes sure that on a glibc system
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* <features.h> is included, which again defines __GLIBC__
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*/
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#include <unistd.h>
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#include <stdio.h> /* puts */
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#include <time.h> /* nanosleep */
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#include <errno.h>
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#include <stdlib.h>
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#include <string.h>
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/*
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* Magic values required to use _reboot() system call.
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*/
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#define LINUX_REBOOT_MAGIC1 0xfee1dead
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#define LINUX_REBOOT_MAGIC2 672274793
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#define LINUX_REBOOT_MAGIC2A 85072278
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#define LINUX_REBOOT_MAGIC2B 369367448
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/*
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* Commands accepted by the _reboot() system call.
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*
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* RESTART Restart system using default command and mode.
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* HALT Stop OS and give system control to ROM monitor, if any.
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* CAD_ON Ctrl-Alt-Del sequence causes RESTART command.
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* CAD_OFF Ctrl-Alt-Del sequence sends SIGINT to init task.
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* POWER_OFF Stop OS and remove all power from system, if possible.
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* RESTART2 Restart system using given command string.
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*/
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#define LINUX_REBOOT_CMD_RESTART 0x01234567
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#define LINUX_REBOOT_CMD_HALT 0xCDEF0123
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#define LINUX_REBOOT_CMD_CAD_ON 0x89ABCDEF
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#define LINUX_REBOOT_CMD_CAD_OFF 0x00000000
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#define LINUX_REBOOT_CMD_POWER_OFF 0x4321FEDC
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#define LINUX_REBOOT_CMD_RESTART2 0xA1B2C3D4
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#define USE_LIBC
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#ifdef USE_LIBC
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/* libc version */
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#if defined __GLIBC__ && __GLIBC__ >= 2
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# include <sys/reboot.h>
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# define REBOOT(cmd) reboot(cmd)
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#else
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extern int reboot(int, int, int);
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# define REBOOT(cmd) reboot(LINUX_REBOOT_MAGIC1,LINUX_REBOOT_MAGIC2,(cmd))
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#endif
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static int my_reboot(int cmd)
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{
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return REBOOT(cmd);
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}
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#else /* no USE_LIBC */
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/* direct syscall version */
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#include <linux/unistd.h>
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#ifdef _syscall3
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_syscall3(int, reboot, int, magic, int, magic_too, int, cmd);
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#else
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/* Let us hope we have a 3-argument reboot here */
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extern int reboot(int, int, int);
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#endif
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static int my_reboot(int cmd)
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{
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return reboot(LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2, cmd);
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}
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#endif
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static void do_reboot(void)
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{
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my_reboot(LINUX_REBOOT_CMD_RESTART);
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}
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static void do_poweroff(void)
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{
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my_reboot(LINUX_REBOOT_CMD_POWER_OFF);
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}
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static void do_halt(void)
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{
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my_reboot(LINUX_REBOOT_CMD_HALT);
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}
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static void usage(void)
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{
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puts(
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"Usage: hardshutdown -h|-r|-p [NN]\n"
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" NN - seconds to sleep before requested action"
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);
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exit(1);
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}
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enum action_t {
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SHUTDOWN, // do nothing
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HALT,
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POWEROFF,
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REBOOT
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};
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int main(int argc, char *argv[])
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{
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struct timespec t = {0,0};
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enum action_t action = SHUTDOWN;
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int c, i;
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char *prog, *ptr;
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//if (*argv[0] == '-') argv[0]++; /* allow shutdown as login shell */
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prog = argv[0];
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ptr = strrchr(prog,'/');
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if (ptr)
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prog = ptr+1;
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for (c=1; c < argc; c++) {
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if (argv[c][0] >= '0' && argv[c][0] <= '9') {
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t.tv_sec = strtol(argv[c], NULL, 10);
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continue;
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}
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if (argv[c][0] != '-') {
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usage();
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return 1;
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}
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for (i=1; argv[c][i]; i++) {
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switch (argv[c][i]) {
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case 'h':
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action = HALT;
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break;
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case 'p':
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action = POWEROFF;
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break;
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case 'r':
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action = REBOOT;
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break;
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default:
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usage();
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return 1;
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}
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}
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}
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if (action==SHUTDOWN) {
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usage();
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return 1;
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}
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chdir("/");
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while (nanosleep(&t,&t)<0)
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if (errno!=EINTR) break;
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switch (action) {
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case HALT:
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do_halt();
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break;
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case POWEROFF:
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do_poweroff();
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break;
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case REBOOT:
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do_reboot();
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break;
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default: /* SHUTDOWN */
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break;
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}
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return 1;
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}
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8
examples/shutdown-1.0/script/hardshutdown.make.sh
Executable file
8
examples/shutdown-1.0/script/hardshutdown.make.sh
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#!/bin/sh
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gcc -Wall -Os -o hardshutdown hardshutdown.c
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strip hardshutdown
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#or:
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#diet gcc -Wall -o hardshutdown hardshutdown.c
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#elftrunc hardshutdown
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64
examples/shutdown-1.0/script/shutdown
Executable file
64
examples/shutdown-1.0/script/shutdown
Executable file
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#!/bin/sh
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PATH=/sbin:/usr/sbin:/bin:/usr/bin
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# Usually, /sbin/ has symlinks named halt, reboot, poweroff
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# (and also possibly shutdown) to e.g.
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# /app/shutdown-1.0/script/shutdown (this file).
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cd /app/shutdown-1.0/script || exit 1
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test -x ./do_shutdown || exit 1
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test -x ./hardshutdown || exit 1
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# "reboot -f" -> "shutdown -f -r" -> "hardshutdown -r" -> immediate reboot
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# "reboot" -> "shutdown -r" -> "do_shutdown -r"
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# ^^^^^^^^^^^^^^^^^^ similarly for halt, poweroff.
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# "shutdown" -> "do_shutdown" (everything killed/unmounted, but kernel not asked to do any poweroff etc)
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force=""
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test x"$1" = x"-f" && {
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force="-f"
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shift
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}
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test ! "$*" && test x"${0##*/}" = x"halt" && exec "$0" $force -h
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test ! "$*" && test x"${0##*/}" = x"reboot" && exec "$0" $force -r
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test ! "$*" && test x"${0##*/}" = x"poweroff" && exec "$0" $force -p
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# We have something else than allowed parameters?
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test x"$*" = x"" || test x"$*" = x"-h" || test x"$*" = x"-r" || test x"$*" = x"-p" || {
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echo "Syntax: $0 [-f] [-h/-r/-p]"
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exit 1
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}
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# Emergency shutdown?
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test "$force" && {
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exec ./hardshutdown "$@"
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exit 1
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}
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# Normal shutdown
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# We must have these executables on root fs
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# (mount/umount aren't checked, all systems are ok versus that):
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test -x /bin/killall5 -o -x /sbin/killall5 || exit 1
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test -x /bin/ps -o -x /sbin/ps || exit 1
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test -x /bin/date -o -x /sbin/date || exit 1
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test -x /bin/xargs -o -x /sbin/xargs || exit 1
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test -x /bin/wc -o -x /sbin/wc || exit 1
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test -x /bin/cat -o -x /sbin/cat || exit 1
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test -x /bin/sort -o -x /sbin/sort || exit 1
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i="`ulimit -n`"
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echo -n "Closing file descriptors $i-3... "
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while test "$i" -ge 3; do
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eval "exec $i>&-"
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i=$((i-1))
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done
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echo "Shutting down. Please stand by..."
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# setsid & /dev/null:
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# make it a process leader & detach it from current tty.
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# Why /dev/null and not /dev/console?
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# I have seen a system which locked up while opening /dev/console
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# due to the bug (?) in keyboard driver.
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setsid env - PATH="$PATH" ./do_shutdown "$@" </dev/null >/dev/null 2>&1 &
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while true; do read junk; done
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81
examples/shutdown-1.0/script/stop_storage
Executable file
81
examples/shutdown-1.0/script/stop_storage
Executable file
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#!/bin/sh
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# Do unmount/remount-ro. Wait.
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# KILL everybody. Wait.
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# Repeat.
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umountcnt=2
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writeout=0 # increase if your kernel doesn ot guarantee writes to complete
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# No /usr - we are expecting all binaries to be accessible
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# from root fs alone
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PATH=/sbin:/bin
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say() {
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printf "\r%s\n\r" "$*"
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}
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showps() {
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# sleep 1 ensures that xargs will have time to start up
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# this makes pslist less prone to random jitter
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pslist=`{ sleep 1; ps -A -o comm=; } | sort | xargs`
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pscnt=$(( `say "$pslist" | wc -w` + 0 ))
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if test x"$VERBOSE" = x; then
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say "* `date '+%H:%M:%S'` $pscnt processes"
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else
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say "* `date '+%H:%M:%S'` Processes ($pscnt): $pslist"
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fi
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}
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say "<*> `date '+%Y-%m-%d %H:%M:%S'` Executing '$0 $*'"
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showps
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i="$umountcnt"
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while test "$i" -gt 0; do
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say "* `date '+%H:%M:%S'` Unmounting filesystems"
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umount -a -n -r -f
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# In case we unmounted proc...
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test -e /proc/version || mount -t proc none /proc
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# Remounting / RO isn't necessary when /etc/mtab is linked to /proc/mounts:
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# already done. But let's be more paranoid here...
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say "* `date '+%H:%M:%S'` Remounting root filesystem read-only"
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mount -n -o remount,ro /
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say "* `date '+%H:%M:%S'` Freeing loop devices"
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for a in /dev/loop*; do
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test -b "$a" && losetup -d "$a"
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done
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say "* `date '+%H:%M:%S'` Syncing"
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sync
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say "* `date '+%H:%M:%S'` Executing: killall5 -KILL"
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killall5 -9
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showps
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i=$((i-1))
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done
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say "* `date '+%H:%M:%S'` Filesystem status (/proc/mounts)"
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cat /proc/mounts \
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| {
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bad=false
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while read dev mntpoint fstype opt n1 n2; do
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case "$fstype" in
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( proc | sysfs | usbfs | devpts | rpc_pipefs | binfmt_misc | autofs | rootfs | tmpfs | ramfs )
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say "$dev $mntpoint $fstype $opt $n1 $n2"
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continue
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;;
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esac
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if test "${opt:0:2}" = "rw"; then
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say "$dev $mntpoint $fstype $opt $n1 $n2 - RW!"
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bad=true
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else
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say "$dev $mntpoint $fstype $opt $n1 $n2"
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fi
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done
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if $bad; then
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say "ERROR: we have filesystems mounted RW! Press <Enter> (^J)..."
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read junk </dev/console
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#sh </dev/console >&0 2>&0 # debug
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fi
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}
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# Disk cache writeout
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sleep "$writeout"
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70
examples/shutdown-1.0/script/stop_tasks
Executable file
70
examples/shutdown-1.0/script/stop_tasks
Executable file
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#!/bin/sh
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# We are trying to be nice.
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# TERM everybody. Give them some time to die.
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# KILL might make some filesystems non-unmountable,
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# so we'll do it in stop_storage instead.
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killcnt=30
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PATH=/sbin:/usr/sbin:/bin:/usr/bin
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echo "<*> `date '+%Y-%m-%d %H:%M:%S'` Executing '$0 $*'"
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showps() {
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# sleep 1 ensures that xargs will have time to start up.
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# This makes pslist less prone to random jitter.
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pslist=`{ sleep 1; ps -A -o comm=; } | sort | xargs`
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pscnt=$(( `echo "$pslist" | wc -w` + 0 ))
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if test x"$VERBOSE" = x; then
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echo "* `date '+%H:%M:%S'` $pscnt processes"
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else
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echo "* `date '+%H:%M:%S'` Processes ($pscnt): $pslist"
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fi
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}
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# Sync.
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# Rationale: sometimes buggy root processes can
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# hang the system when killed (X for example may have problems
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# with restoring text mode on a poorly supported hardware).
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# These are bugs and must be fixed, but until then users will lose
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# dirty data on shutdown! Let's make that less likely.
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sync &
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# Send SIGTERMs. If list of processes changes, proceed slower.
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# If it has stabilised (all who wanted to, exited), proceed faster.
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showps
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i="$killcnt"
|
||||
while test "$i" -gt 0; do
|
||||
echo "* `date '+%H:%M:%S'` Sending CONT, TERM" #, HUP"
|
||||
# I've seen "killall5 2.86" which doesn't grok signal names!
|
||||
killall5 -18
|
||||
killall5 -15
|
||||
#killall5 -1 # HUP: because interactive bash does not die on TERM...
|
||||
# but init will reread /etc/inittab on HUP and my /etc is on non root fs!
|
||||
# -> umounts will complain.
|
||||
oldpslist="$pslist"
|
||||
showps
|
||||
if test x"$pslist" = x"$oldpslist"; then
|
||||
i=$((i-8))
|
||||
fi
|
||||
i=$((i-2))
|
||||
done
|
||||
|
||||
echo "* `date '+%H:%M:%S'` Turning off swap"
|
||||
swapoff -a
|
||||
cat /proc/swaps | grep -v ^Filename | cut -d ' ' -f1 \
|
||||
| while read -r line; do
|
||||
test "$line" && {
|
||||
echo swapoff "$line"
|
||||
swapoff "$line"
|
||||
}
|
||||
done
|
||||
|
||||
echo "* /proc/swaps:"
|
||||
cat /proc/swaps
|
||||
echo "* /proc/mounts:"
|
||||
cat /proc/mounts
|
||||
echo "* ps -A e:"
|
||||
ps -A e
|
||||
echo "* top -bn1:"
|
||||
top -bn1
|
||||
Loading…
Reference in New Issue
Block a user