update: 2016/02/19
reference:
1. 樹莓派硬體看門狗（Watchdog）：當機時自動重新開機 - G. T. Wang
2. ssmtp to send emails – Raspberry Pi Projects
A. Sending Email From Your System with sSMTP
1. 安裝套件:
$ sudo apt-get install ssmtp
$ sudo apt-get install mailutils
2. 編輯設定檔:
$ sudo nano /etc/ssmtp/ssmtp.conf
#
# Config file for sSMTP sendmail
#
# The person who gets all mail for userids < 1000
# Make this empty to disable rewriting.
#root=postmaster
root=lanlixxxx@gmail.com
# The place where the mail goes. The actual machine name is required no
# MX records are consulted. Commonly mailhosts are named mail.domain.com
#mailhub=mail
mailhub=smtp.gmail.com:587
# Where will the mail seem to come from?
#rewriteDomain=
# The full hostname
hostname=raspberrypi
# Auth
AuthUser=pythonicxxxx@gmail.com
AuthPass=pythonxxxx
# Are users allowed to set their own From: address?
# YES - Allow the user to specify their own From: address
# NO - Use the system generated From: address
FromLineOverride=YES
UseSTARTTLS=YES
3. 降低寄發郵件的安全性設定: (AuthUser)
> GMail 低安全性應用程式 - 帳戶設定
$ echo "Hello world email body" | mail -s "Test Subject" lanlixxxx@gmail.com
5. 寄發 "附加檔案" 測試郵件:
$ sudo apt-get install mpack
$
mpack -s "Test" somefile.txt lanlixxxx@gmail.com-----------------------------------------------------------------------------------------------
B. 安裝 watchdog
1. 啟用 bcm2708_wdog 核心模組
$ sudo nano /etc/modules
# /etc/modules: kernel modules to load at boot time.
#
# This file contains the names of kernel modules that should be loaded
# at boot time, one per line. Lines beginning with "#" are ignored.
i2c-dev
bcm2708_wdog
2. 立即啟用：
$ sudo modprobe bcm2708_wdog
3. 安裝 watchdog 監控 Daemon
$ sudo apt-get install watchdog
-----------------------------------------------------------------------------------------------
C. 編輯 watchdog 設定檔
$ sudo nano /etc/watchdog.conf
#ping = 172.31.14.1
#ping = 172.26.1.255
#interface = eth0#interface = wlan0
# 監控檔案是否可以正常存取
#file = /var/log/messages
#change = 1407
# Uncomment to enable test. Setting one of these values to '0' disables it.
# These values will hopefully never reboot your machine during normal use
# (if your machine is really hung, the loadavg will go much higher than 25)
max-load-1 = 24
max-load-5 = 18
max-load-15 = 12
# Note that this is the number of pages!
# To get the real size, check how large the pagesize is on your machine.
# 查看自己系統的 page size
# getconf PAGESIZE (4096)
#
#min-memory = 1 (一張 page 的大小就是 4096 bytes)
#allocatable-memory = 1
#repair-binary = /usr/sbin/repair
#repair-timeout =
#test-binary =
#test-timeout =
watchdog-device = /dev/watchdog
# Defaults compiled into the binary
// 檢查 CPU 溫度 (單位: 攝氏千分之一度)
// cat /sys/class/thermal/thermal_zone0/temp (35780)
#temperature-device = /sys/class/thermal/thermal_zone0/temp
#max-temperature = 120
#max-temperature = 80000
# Defaults compiled into the binary
#admin = root
admin = lanlixxxx@gmail.com
#interval = 1
#logtick = 1
#log-dir = /var/log/watchdog
# This greatly decreases the chance that watchdog won't be scheduled before
# your machine is really loaded
realtime = yes
priority = 1
# Check if rsyslogd is still running by enabling the following line
#pidfile = /var/run/rsyslogd.pid
-----------------------------------------------------------------------------------------------
D. 調整: (for 新版 Pi OS: 2016-02-09-raspbian-jessie; still may not work)
$ sudo nano /lib/systemd/system/watchdog.service
[Unit]
Description=watchdog daemon
Conflicts=wd_keepalive.service
After=multi-user.target
OnFailure=wd_keepalive.service
[Service]
Type=forking
EnvironmentFile=/etc/default/watchdog
ExecStartPre=/bin/sh -c '[ -z "${watchdog_module}" ] || [ "${watchdog_module}" = "none" ] || /sbin/modprobe $watchdog_module
ExecStart=/bin/sh -c '[ $run_watchdog != 1 ] || exec /usr/sbin/watchdog $watchdog_options'
ExecStopPost=/bin/sh -c '[ $run_wd_keepalive != 1 ] || false'
[Install]
WantedBy=multi-user.target
$
systemctl enable watchdog-----------------------------------------------------------------------------------------------
E. 啟動看門狗
1. 立即啟動 watchdog 常駐程式
$ sudo service watchdog start
2. 開機時自動啟動 watchdog
$ sudo update-rc.d watchdog defaults
3. 檢查
$ ps aux | grep watchdog
root 786 0.0 0.3 1888 1760 ? SLs 14:34 0:00 /usr/sbin/watchdog
pi 822 0.0 0.3 4276 1956 pts/0 S+ 14:36 0:00 grep --color=auto watchdog
4. 測試
kill 掉 watchdog 本身, 會重新開機
$ sudo kill -9 786
