无法从 cron 作业重新启动 mysql

Question

我有一个问题，即 MySQL（在 Ubuntu 12.04 上运行所有最新更新）在几天后死亡，因此将此脚本放入一个 cron 作业中，该作业每 60 秒以 root 身份运行。

一切正常，除了 mysql 服务不会重新启动，我试过使用“service mysql restart”和“/usr/bin/mysqld”，但它们也不起作用。

我正在使用完整路径来重新启动命令，所以我认为这不是问题。现在唯一有效的是用“重启”替换重启命令，这非常难看，我想避免它。

#!/bin/bash
#Check if MySQL is up, if not then start it
# mysql root/admin username
MUSER="root"
# mysql admin/root password
MPASS="REMOVED"
# mysql server hostname
MHOST="localhost"
#Shell script to start MySQL server i.e. path to MySQL daemon start/stop script.
# Debain uses following script, need to setup this according to your UNIX/Linux/BSD OS.
MSTART="/etc/init.d/mysql restart"
# Email ID to send notification
EMAILID="some@email.net"
# path mysqladmin
MADMIN="$(which mysqladmin)"

MAILMESSAGE="/tmp/mysql.fail.$$"

# see if MySQL server is alive or not

$MADMIN -h $MHOST -u $MUSER -p${MPASS} ping 2>/dev/null 1>/dev/null
if [ $? -ne 0 ]; then
        echo "" >$MAILMESSAGE
        echo "ALERT: MySQL Server is not responding to ping">>$MAILMESSAGE
        echo "Hostname: $(hostname)" >>$MAILMESSAGE
        echo "System Time: $(date)" >>$MAILMESSAGE
        # try to start mysql
        $MSTART>/dev/null
        # see if it is started or not
        o=$(ps cax | grep -c ' mysqld$')
        if [ $o -eq 1 ]; then
                sMess="MySQL server successfully restarted"
        else
                sMess="MySQL server FAILED to restart"
        fi
        # Email status too
        echo "Current Status: $sMess" >>$MAILMESSAGE
        echo "" >>$MAILMESSAGE
        echo "*** This email generated by $(basename $0) shell script ***" >>$MAILMESSAGE
        echo "*** Please don't reply this email, this is just notification email ***" >>$MAILMESSAGE
        # send email
        sendemail -o message-content-type=text -f some@email.net -t $EMAILID -u MySQL GURU ALARM -m < $MAILMESSAGE
else # MySQL is running :) and do nothing
        :
fi
# remove file
rm -f $MAILMESSAGE

Answer 1

如果不查看启动错误日志，几乎不可能进行诊断。

如果我不得不冒险猜测，这听起来可能有问题ulimit，进程可能无法从 cron 分配它需要的内存，但在通过交互式 shell 运行时不受限制。MySQL 日志会确认这一点，尽管是以一种非描述性的方式。

另外，不要用半翘起的脚本重新发明轮子，只需使用公认的监控应用程序，如 monit