2023年6月25日发(作者：)

MySQL启动脚本详解今晚看了下5.6.24版本中的脚本，发现与5.1中的脚本有了很⼤的改变。我们经常⽤到的/etc/init.d/mysql 这个启动脚本就是拷贝的先把脚本贴出来#!/bin/sh# Copyright Abandoned 1996 TCX DataKonsult AB & Monty Program KB & Detron HB# This file is public domain and comes with NO WARRANTY of any kind# MySQL daemon start/stop script.# Usually this is put in /etc/init.d (at least on machines SYSV R4 based# systems) and linked to /etc/rc3.d/S99mysql and /etc/rc0.d/K01mysql.# When this is done the mysql server will be started when the machine is# started and shut down when the systems goes down.# Comments to support chkconfig on RedHat Linux# chkconfig: 2345 64 36# description: A very fast and reliable SQL database engine.# Comments to support LSB init script conventions### BEGIN INIT INFO# Provides: mysql# Required-Start: $local_fs $network $remote_fs# Should-Start: ypbind nscd ldap ntpd xntpd# Required-Stop: $local_fs $network $remote_fs# Default-Start: 2 3 4 5# Default-Stop: 0 1 6# Short-Description: start and stop MySQL# Description: MySQL is a very fast and reliable SQL database engine.### END INIT INFO

# If you install MySQL on some other places than /usr/local/mysql, then you# have to do one of the following things for this script to work:## - Run this script from within the MySQL installation directory# - Create a /etc/ file with the following information:# [mysqld]# basedir=# - Add the above to any other configuration file (for example ~/.)# and copy my_print_defaults to /usr/bin# - Add the path to the mysql-installation-directory to the basedir variable# below.## If you want to affect other MySQL variables, you should make your changes# in the /etc/, ~/. or other MySQL configuration files.# If you change base dir, you must also change datadir. These may get# overwritten by settings in the MySQL configuration files.# 如果你的basedir不是默认的/usr/local/mysql⽬录，则需要设置这个参数。# 如果你的datadir不是在$basedir/data⽬录下，则需要设置datadir参数。basedir=datadir=# Default value, in seconds, afterwhich the script should timeout waiting# for server start.

# Value here is overriden by value in .

# 0 means don't wait at all# Negative numbers mean to wait indefinitelyservice_startup_timeout=900# Lock directory for RedHat / r='/var/lock/subsys'lock_file_path="$lockdir/mysql"# The following variables are only set for letting find things.#如果basedir或者datadir为空，则给与相应的默认值。同时设置对应的sbindir和libexecdir变量值。# Set some defaultsmysqld_pid_file_path=if test -z "$basedir"then basedir=/usr/local/mysql bindir=/usr/local/mysql/bin if test -z "$datadir" then datadir=/usr/local/mysql/data fi sbindir=/usr/local/mysql/bin libexecdir=/usr/local/mysql/binelse bindir="$basedir/bin" if test -z "$datadir" then datadir="$basedir/data" fi sbindir="$basedir/sbin" libexecdir="$basedir/libexec"fi# datadir_set is used to determine if datadir was set (and so should be# *not* set inside of the --basedir= handler.)datadir_set=## Use LSB init script functions for printing messages, if possible# 如果得到系统⾃带⽇志函数，则使⽤，否则⽤⾃⼰的⽇志函数。lsb_functions="/lib/lsb/init-functions"if test -f $lsb_functions ; then . $lsb_functionselse log_success_msg() { echo " SUCCESS! $@" } log_failure_msg() { echo " ERROR! $@" }fi#设置PATH环境变量PATH="/sbin:/usr/sbin:/bin:/usr/bin:$basedir/bin"export PATHmode=$1 # start or stop[ $# -ge 1 ] && shift#将第⼀个参数后的其他参数赋予other_args变量。other_args="$*" # uncommon, but needed when called from an RPM upgrade action # Expected: "--skip-networking --skip-grant-tables" # They are not checked here, intentionally, as it is the resposibility # of the "spec" file author to give correct arguments `echo "testingc"`,`echo -n testing` in *c*,-n*) echo_n= echo_c= ;; *c*,*) echo_n=-n echo_c= ;; *) echo_n= echo_c='c' ;;esac#参数解析函数（将参数值赋予对于变量）parse_server_arguments() { for arg do case "$arg" in --basedir=*) basedir=`echo "$arg" | sed -e 's/^[^=]*=//'` bindir="$basedir/bin" if test -z "$datadir_set"; then datadir="$basedir/data" fi sbindir="$basedir/sbin" libexecdir="$basedir/libexec" ;; --datadir=*) datadir=`echo "$arg" | sed -e 's/^[^=]*=//'` datadir_set=1 ;; --pid-file=*) mysqld_pid_file_path=`echo "$arg" | sed -e 's/^[^=]*=//'` ;; --service-startup-timeout=*) service_startup_timeout=`echo "$arg" | sed -e 's/^[^=]*=//'` ;; esac done}wait_for_pid () { verb="$1" # created | removed pid="$2" # process ID of the program operating on the pid-file pid_file_path="$3" # path to the PID file. i=0 avoid_race_condition="by checking again" while test $i -ne $service_startup_timeout ; do case "$verb" in 'created') # wait for a PID-file to pop into existence. test -s "$pid_file_path" && i='' && break ;; 'removed') # wait for this PID-file to disappear test ! -s "$pid_file_path" && i='' && break ;; *) echo "wait_for_pid () usage: wait_for_pid created|removed pid pid_file_path" exit 1 ;; esac # if server isn't running, then pid-file will never be updated if test -n "$pid"; then if kill -0 "$pid" 2>/dev/null; then : # the server still runs else # The server may have exited between the last pid-file check and now.

if test -n "$avoid_race_condition"; then avoid_race_condition="" continue # Check again. fi # there's nothing that will affect the file. log_failure_msg "The server quit without updating PID file ($pid_file_path)." return 1 # not waiting any more. fi fi echo $echo_n ".$echo_c" i=`expr $i + 1` i=`expr $i + 1` sleep 1 done if test -z "$i" ; then log_success_msg return 0 else log_failure_msg return 1 fi}# Get arguments from the file,# the only group, which is read from now on is [mysqld]#得到有执⾏权限的my_print_defaults程序（这个程序是将中的参数打印出来，#其读取的顺序是/etc/ /etc/mysql/ /usr/local/mysql/etc/ ~/.，后⾯的参数会覆盖掉前⾯的参数）if test -x ./bin/my_print_defaultsthen print_defaults="./bin/my_print_defaults"elif test -x $bindir/my_print_defaultsthen print_defaults="$bindir/my_print_defaults"elif test -x $bindir/mysql_print_defaultsthen print_defaults="$bindir/mysql_print_defaults"else # Try to find basedir in /etc/ conf=/etc/ print_defaults= if test -r $conf then subpat='^[^=]*basedir[^=]*=(.*)$' dirs=`sed -e "/$subpat/!d" -e 's//1/' $conf` for d in $dirs do d=`echo $d | sed -e 's/[ ]//g'` if test -x "$d/bin/my_print_defaults" then print_defaults="$d/bin/my_print_defaults" break fi if test -x "$d/bin/mysql_print_defaults" then print_defaults="$d/bin/mysql_print_defaults" break fi done fi # Hope it's in the PATH ... but I doubt it test -z "$print_defaults" && print_defaults="my_print_defaults"fi## Read defaults file from 'basedir'. If there is no defaults file there# check if it's in the old (depricated) place (datadir) and read it from there##获取附加的。这个⾥的参数值会覆盖其他的参数设置。#注意，如果basedir下有就不会再去读取datadir下的。如果basedir下⾯没有则会继续读取datadir下的。extra_args=""if test -r "$basedir/"then extra_args="-e $basedir/"elseelse if test -r "$datadir/" then extra_args="-e $datadir/" fifi#将my_print_defaults程序打印出来的Mysql参数⽤parse_server_arguments进⾏解析，解析后的值会是这个脚本环境中的变量值。parse_server_arguments `$print_defaults $extra_args mysqld server mysql_server `## Set pid file if not given#设置mysqld_pid_file_path变量（其代表pid ⽂件的位置），如果没有设置这个值或者不是绝对路径，则默认会在$datadir下⾯if test -z "$mysqld_pid_file_path"then mysqld_pid_file_path=$datadir/`hostname`.pidelse case "$mysqld_pid_file_path" in /* ) ;; * ) mysqld_pid_file_path="$datadir/$mysqld_pid_file_path" ;; esacficase "$mode" in 'start') # Start daemon # Safeguard (relative paths, core dumps..) cd $basedir echo $echo_n "Starting MySQL" if test -x $bindir/mysqld_safe then # Give extra arguments to mysqld with the file. This script # may be overwritten at next upgrade. #真正启动数据库就是下⾯这条命令。 $bindir/mysqld_safe --datadir="$datadir" --pid-file="$mysqld_pid_file_path" $other_args >/dev/null 2>&1 & wait_for_pid created "$!" "$mysqld_pid_file_path"; return_value=$? # Make lock for RedHat / SuSE if test -w "$lockdir" then touch "$lock_file_path" fi exit $return_value else log_failure_msg "Couldn't find MySQL server ($bindir/mysqld_safe)" fi ;; 'stop') # Stop daemon. We use a signal here to avoid having to know the # root password. if test -s "$mysqld_pid_file_path" then mysqld_pid=`cat "$mysqld_pid_file_path"` if (kill -0 $mysqld_pid 2>/dev/null) then echo $echo_n "Shutting down MySQL" kill $mysqld_pid # mysqld should remove the pid file when it exits, so wait for it. wait_for_pid removed "$mysqld_pid" "$mysqld_pid_file_path"; return_value=$? else log_failure_msg "MySQL server process #$mysqld_pid is not running!" log_failure_msg "MySQL server process #$mysqld_pid is not running!" rm "$mysqld_pid_file_path" fi # Delete lock for RedHat / SuSE if test -f "$lock_file_path" then rm -f "$lock_file_path" fi exit $return_value else log_failure_msg "MySQL server PID file could not be found!" fi ;; 'restart') # Stop the service and regardless of whether it was # running or not, start it again. if $0 stop $other_args; then $0 start $other_args else log_failure_msg "Failed to stop running server, so refusing to try to start." exit 1 fi ;; 'reload'|'force-reload') if test -s "$mysqld_pid_file_path" ; then read mysqld_pid < "$mysqld_pid_file_path" kill -HUP $mysqld_pid && log_success_msg "Reloading service MySQL" touch "$mysqld_pid_file_path" else log_failure_msg "MySQL PID file could not be found!" exit 1 fi ;; 'status') # First, check to see if pid file exists if test -s "$mysqld_pid_file_path" ; then

read mysqld_pid < "$mysqld_pid_file_path" if kill -0 $mysqld_pid 2>/dev/null ; then

log_success_msg "MySQL running ($mysqld_pid)" exit 0 else log_failure_msg "MySQL is not running, but PID file exists" exit 1 fi else # Try to find appropriate mysqld process mysqld_pid=`pidof $libexecdir/mysqld` # test if multiple pids exist pid_count=`echo $mysqld_pid | wc -w` if test $pid_count -gt 1 ; then log_failure_msg "Multiple MySQL running but PID file could not be found ($mysqld_pid)" exit 5 elif test -z $mysqld_pid ; then

if test -f "$lock_file_path" ; then

log_failure_msg "MySQL is not running, but lock file ($lock_file_path) exists" exit 2 fi

log_failure_msg "MySQL is not running" exit 3 else log_failure_msg "MySQL is running but PID file could not be found" exit 4 exit 4 fi fi ;; *) # usage basename=`basename "$0"` echo "Usage: $basename {start|stop|restart|reload|force-reload|status} [ MySQL server options ]" exit 1 ;;esacexit 0