本文详细解析了Mysql的启动脚本，包括环境变量设置、日志处理、异常重启策略及权限调整等内容，深入理解Mysql守护进程的运行机制。
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#!/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##脚本用于启动Mysql 守护进程和mysqld异常die后重启# Script to start the MySQL daemon and restart it if it dies unexpectedly#需要在MYSQL base目录下执行, 使用你使用一个2进制安装,不是安装在编译时默认的目录# This should be executed in the MySQL base directory if you are using a# binary installation that is not installed in its compile-time default# location## mysql.server works by first doing a cd to the base directory and from there# executing mysqld_safe#初始化脚本参数# Initialize script globalsKILL_MYSQLD=1;#试图kill多余的mysqld_safe程序，1表示需要kill MYSQLD=niceness=0 # 进程的调度优先级标识 mysqld_ld_preload=mysqld_ld_library_path=# Initial logging status: error log is not open, and not using sysloglogging=initwant_syslog=0 # 标识是否要使用syslog syslog_tag=user='mysql'pid_file=err_log=syslog_tag_mysqld=mysqldsyslog_tag_mysqld_safe=mysqld_safe# # 不允许程序在终端上被人打断（包括挂起，中断，退出，系统终止的情形） trap '' 1 2 3 15 # we shouldn't let anyone kill ustrap '' 13 # not even SIGPIPE# MySQL-specific environment variable. First off, it's not really a umask,# it's the desired mode. Second, it follows umask(2), not umask(3) in that# octal needs to be explicit. Our shell might be a proper sh without printf,# multiple-base arithmetic, and binary arithmetic, so this will get ugly.# We reject decimal values to keep things at least half-sane.#MYSQL指定环境变量,首先 这个不是真正的umask,它只是一个需要的模式。第二,它遵循umask(2),不是umask(3)#八进制需要被显示,我们的shell可能是正常的sh 乜有printf#多个base计算,binary 计算 这样会变得丑陋#我们拒绝10进制只来保持umask 007 # fallback#[mysql@master ~]$ UMASK="${UMASK-0640}"#[mysql@master ~]$ echo $UMASK#0640UMASK="${UMASK-0640}"##把非0246替换为空fmode=`echo "$UMASK" | sed -e 's/[^0246]//g'`##取第一个数字 #[mysql@master ~]$ echo $octalp#0octalp=`echo "$fmode"|cut -c1`#统计字符数 #[mysql@master ~]$ echo "$fmode"|wc -c|sed -e 's/ //g'#5fmlen=`echo "$fmode"|wc -c|sed -e 's/ //g'`##或者if [ "x$octalp" != "x0" -o "x$UMASK" != "x$fmode" -o "x$fmlen" != "x5" ]then fmode=0640 ## UMASK 必须是3位数字模式 开头是0来表明8进制 echo "UMASK must be a 3-digit mode with an additional leading 0 to indicate octal." >&2 echo "The first digit will be corrected to 6, the others may be 0, 2, 4, or 6." >&2fi##[mysql@master ~]$ echo "$fmode"|cut -c3-4##40fmode=`echo "$fmode"|cut -c3-4`fmode="6$fmode"if [ "x$UMASK" != "x0$fmode" ]then echo "UMASK corrected from $UMASK to 0$fmode ..."fi# defaults变量记载使用的配置文件的信息 --defaults-file=/etc/my.cnf defaults=case "$1" in --no-defaults|--defaults-file=*|--defaults-extra-file=*) defaults="$1"; shift ;;esacusage () { cat <<EOFUsage: $0 [OPTIONS] --no-defaults Don't read the system defaults file --defaults-file=FILE Use the specified defaults file --defaults-extra-file=FILE Also use defaults from the specified file --ledir=DIRECTORY Look for mysqld in the specified directory --open-files-limit=LIMIT Limit the number of open files --core-file-size=LIMIT Limit core files to the specified size --timezone=TZ Set the system timezone --malloc-lib=LIB Preload shared library LIB if available --mysqld=FILE Use the specified file as mysqld --mysqld-version=VERSION Use "mysqld-VERSION" as mysqld --nice=NICE Set the scheduling priority of mysqld --plugin-dir=DIR Plugins are under DIR or DIR/VERSION, if VERSION is given --skip-kill-mysqld Don't try to kill stray mysqld processes --syslog Log messages to syslog with 'logger' --skip-syslog Log messages to error log (default) --syslog-tag=TAG Pass -t "mysqld-TAG" to 'logger'All other options are passed to the mysqld program.EOF exit 1}my_which (){ save_ifs="${IFS-UNSET}" # 保存当前的内建分隔符，用于后面重置IFS IFS=: # 使用:来分割PATH中的路径 ret=0 for file # 这种写法等同于for file in $@ do for dir in $PATH do if [ -f "$dir/$file" ] then echo "$dir/$file" continue 2 # continue 第 2 层, 这里就是跳出本层for循环,跳到外层for循环 fi done ret=1 #signal an error break done if [ "$save_ifs" = UNSET ] then unset IFS else IFS="$save_ifs" fi return $ret # Success}# 日志输出函数，这是个原型，后面被log_error和log_notice函数引用 log_generic () {# priority 代表日志信息的分类，从后面的两个函数可知有：daemon.error和daemon.notice两种类别 priority="$1" shift msg="`date +'%y%m%d %H:%M:%S'` mysqld_safe $*" echo "$msg" case $logging in init) ;; # 初始化状态时，只在命令行输出msg信息，不记录日志 file) echo "$msg" >> "$err_log" ;; # 记录到err_log中 syslog) logger -t "$syslog_tag_mysqld_safe" -p "$priority" "$*" ;;# 使用logger记录到系统日志中 *) echo "Internal program error (non-fatal):" \ " unknown logging method '$logging'" >&2 ;; esac}log_error () { log_generic daemon.error "$@" >&2}log_notice () { log_generic daemon.notice "$@"}# 后面就是用它启动的mysqld，通过logging变量区分记录日志的类型，分错误日志和系统日志syslog两种 # 最后的eval命令会解析 $cmd 中的值并执行命令#$cmd is nohup /usr/local/mysql5.6/bin/mysqld --basedir=/usr/local/mysql5.6 --datadir=/usr/local/mysql5.6/data --plugin-dir=/usr/local/mysql5.6/lib/plugin --log-error=/usr/local/mysql5.6/data/master.err --pid-file=/usr/local/mysql5.6/data/master.pid < /dev/nulleval_log_error () { cmd="$1" case $logging in file) cmd="$cmd >> "`shell_quote_string "$err_log"`" 2>&1" ;; syslog) # mysqld often prefixes its messages with a timestamp, which is # redundant when logging to syslog (which adds its own timestamp) # However, we don't strip the timestamp with sed here, because # sed buffers output (only GNU sed supports a -u (unbuffered) option) # which means that messages may not get sent to syslog until the # mysqld process quits. cmd="$cmd 2>&1 | logger -t '$syslog_tag_mysqld' -p daemon.error" ;; *) echo "Internal program error (non-fatal):" \ " unknown logging method '$logging'" >&2 ;; esac #echo "Running mysqld: [$cmd]" eval "$cmd"}shell_quote_string() { # This sed command makes sure that any special chars are quoted, # so the arg gets passed exactly to the server. echo "$1" | sed -e 's,\([^a-zA-Z0-9/_.=-]\),\\\1,g'}# 该函数用于解析配置文件中的选项，并赋值给相应的变量 parse_arguments() { # We only need to pass arguments through to the server if we don't # handle them here. So, we collect unrecognized options (passed on # the command line) into the args variable. ##我们只能通过server 传递参数 如果我们不能处理他们。因此,我们收集不认识的选项 ##通过命令行选项传递参数 pick_args= if test "$1" = PICK-ARGS-FROM-ARGV then pick_args=1 shift fi# 取出参数值，比如 --port=3306 结果为： val = 3306 注意这里sed中使用；来分割，等同于/ #这里的for arg 相当于for arg in $@ for arg do # the parameter after "=", or the whole $arg if no match val=`echo "$arg" | sed -e 's;^--[^=]*=;;'` # what's before "=", or the whole $arg if no match optname=`echo "$arg" | sed -e 's/^\(--[^=]*\)=.*$/\1/'` # replace "_" by "-" ; mysqld_safe must accept "_" like mysqld does. optname_subst=`echo "$optname" | sed 's/_/-/g'` arg=`echo $arg | sed "s/^$optname/$optname_subst/"` case "$arg" in # # 将参数值传递给对应的变量 --basedir=*) MY_BASEDIR_VERSION="$val" ;; --datadir=*) DATADIR="$val" ;; --pid-file=*) pid_file="$val" ;; --plugin-dir=*) PLUGIN_DIR="$val" ;; --user=*) user="$val"; SET_USER=1 ;; # 有些值可能已经在my.cnf配置文件的[mysqld_safe]组下设置了 # 某些值会被命令行上指定的选项值覆盖 --log-error=*) err_log="$val" ;; --port=*) mysql_tcp_port="$val" ;; --socket=*) mysql_unix_port="$val" ;; # mysqld_safe-specific options - must be set in my.cnf ([mysqld_safe])! # 接下来这几个特殊的选项在配置文件的[mysqld_safe]组中是必须设置的 # 我没配置这个组，所以就用不到了（使用mysqld中的默认） --core-file-size=*) core_file_size="$val" ;; --ledir=*) ledir="$val" ;; --malloc-lib=*) set_malloc_lib "$val" ;; --mysqld=*) MYSQLD="$val" ;; --mysqld-version=*) if test -n "$val" then MYSQLD="mysqld-$val" PLUGIN_VARIANT="/$val" else MYSQLD="mysqld" fi ;; --nice=*) niceness="$val" ;; --open-files-limit=*) open_files="$val" ;; --open_files_limit=*) open_files="$val" ;; --skip-kill-mysqld*) KILL_MYSQLD=0 ;; --syslog) want_syslog=1 ;; --skip-syslog) want_syslog=0 ;; --syslog-tag=*) syslog_tag="$val" ;; --timezone=*) TZ="$val"; export TZ; ;; --help) usage ;; *) if test -n "$pick_args" then append_arg_to_args "$arg" fi ;; esac done}# Add a single shared library to the list of libraries which will be added to# LD_PRELOAD for mysqld## Since LD_PRELOAD is a space-separated value (for historical reasons), if a# shared lib's path contains spaces, that path will be prepended to# LD_LIBRARY_PATH and stripped from the lib value.add_mysqld_ld_preload() { lib_to_add="$1" log_notice "Adding '$lib_to_add' to LD_PRELOAD for mysqld" case "$lib_to_add" in *' '*) # Must strip path from lib, and add it to LD_LIBRARY_PATH lib_file=`basename "$lib_to_add"` case "$lib_file" in *' '*) # The lib file itself has a space in its name, and can't # be used in LD_PRELOAD log_error "library name '$lib_to_add' contains spaces and can not be used with LD_PRELOAD" exit 1 ;; esac lib_path=`dirname "$lib_to_add"` lib_to_add="$lib_file" [ -n "$mysqld_ld_library_path" ] && mysqld_ld_library_path="$mysqld_ld_library_path:" mysqld_ld_library_path="$mysqld_ld_library_path$lib_path" ;; esac # LD_PRELOAD is a space-separated [ -n "$mysqld_ld_preload" ] && mysqld_ld_preload="$mysqld_ld_preload " mysqld_ld_preload="${mysqld_ld_preload}$lib_to_add"}# Returns LD_PRELOAD (and LD_LIBRARY_PATH, if needed) text, quoted to be# suitable for use in the eval that calls mysqld.## All values in mysqld_ld_preload are prepended to LD_PRELOAD.mysqld_ld_preload_text() { text= if [ -n "$mysqld_ld_preload" ]; then new_text="$mysqld_ld_preload" [ -n "$LD_PRELOAD" ] && new_text="$new_text $LD_PRELOAD" text="${text}LD_PRELOAD="`shell_quote_string "$new_text"`' ' fi if [ -n "$mysqld_ld_library_path" ]; then new_text="$mysqld_ld_library_path" [ -n "$LD_LIBRARY_PATH" ] && new_text="$new_text:$LD_LIBRARY_PATH" text="${text}LD_LIBRARY_PATH="`shell_quote_string "$new_text"`' ' fi echo "$text"}mysql_config=get_mysql_config() { if [ -z "$mysql_config" ]; then mysql_config=`echo "$0" | sed 's,/[^/][^/]*$,/mysql_config,'` if [ ! -x "$mysql_config" ]; then log_error "Can not run mysql_config $@ from '$mysql_config'" exit 1 fi fi "$mysql_config" "$@"}# set_malloc_lib LIB# - If LIB is empty, do nothing and return# - If LIB is 'tcmalloc', look for tcmalloc shared library in /usr/lib# then pkglibdir. tcmalloc is part of the Google perftools project.# - If LIB is an absolute path, assume it is a malloc shared library## Put LIB in mysqld_ld_preload, which will be added to LD_PRELOAD when# running mysqld. See ld.so for details.set_malloc_lib() { malloc_lib="$1" if [ "$malloc_lib" = tcmalloc ]; then pkglibdir=`get_mysql_config --variable=pkglibdir` malloc_lib= # This list is kept intentionally simple. Simply set --malloc-lib # to a full path if another location is desired. for libdir in /usr/lib "$pkglibdir" "$pkglibdir/mysql"; do for flavor in _minimal '' _and_profiler _debug; do tmp="$libdir/libtcmalloc$flavor.so" #log_notice "DEBUG: Checking for malloc lib '$tmp'" [ -r "$tmp" ] || continue malloc_lib="$tmp" break 2 done done if [ -z "$malloc_lib" ]; then log_error "no shared library for --malloc-lib=tcmalloc found in /usr/lib or $pkglibdir" exit 1 fi fi # Allow --malloc-lib='' to override other settings [ -z "$malloc_lib" ] && return case "$malloc_lib" in /*) if [ ! -r "$malloc_lib" ]; then log_error "--malloc-lib '$malloc_lib' can not be read and will not be used" exit 1 fi ;; *) log_error "--malloc-lib must be an absolute path or 'tcmalloc'; " \ "ignoring value '$malloc_lib'" exit 1 ;; esac add_mysqld_ld_preload "$malloc_lib"}## First, try to find BASEDIR and ledir (where mysqld is)#查找mysqld的basedir和mysqld所在的目录if echo '/usr/local/mysql5./share' | grep '^/usr/local/mysql5.' > /dev/nullthen relpkgdata=`echo '/usr/local/mysql5./share' | sed -e 's,^/usr/local/mysql5.,,' -e 's,^/,,' -e 's,^,./,'`else # pkgdatadir is not relative to prefix relpkgdata='/usr/local/mysql5./share'fiMY_PWD=`pwd`# Check for the directories we would expect from a binary release installif test -n "$MY_BASEDIR_VERSION" -a -d "$MY_BASEDIR_VERSION"then # BASEDIR is already overridden on command line. Do not re-set. # Use BASEDIR to discover le. if test -x "$MY_BASEDIR_VERSION/libexec/mysqld" then ledir="$MY_BASEDIR_VERSION/libexec" elif test -x "$MY_BASEDIR_VERSION/sbin/mysqld" then ledir="$MY_BASEDIR_VERSION/sbin" else ledir="$MY_BASEDIR_VERSION/bin" fielif test -f "$relpkgdata"/english/errmsg.sys -a -x "$MY_PWD/bin/mysqld"then MY_BASEDIR_VERSION="$MY_PWD" # Where bin, share and data are ledir="$MY_PWD/bin" # Where mysqld is# Check for the directories we would expect from a source installelif test -f "$relpkgdata"/english/errmsg.sys -a -x "$MY_PWD/libexec/mysqld"then MY_BASEDIR_VERSION="$MY_PWD" # Where libexec, share and var are ledir="$MY_PWD/libexec" # Where mysqld iselif test -f "$relpkgdata"/english/errmsg.sys -a -x "$MY_PWD/sbin/mysqld"then MY_BASEDIR_VERSION="$MY_PWD" # Where sbin, share and var are ledir="$MY_PWD/sbin" # Where mysqld is# Since we didn't find anything, used the compiled-in defaultselse MY_BASEDIR_VERSION='/usr/local/mysql5.' ledir='/usr/local/mysql5./bin'fi## Second, try to find the data directory#第2步找出数据目录# Try where the binary installs put itif test -d $MY_BASEDIR_VERSION/data/mysqlthen DATADIR=$MY_BASEDIR_VERSION/data if test -z "$defaults" -a -r "$DATADIR/my.cnf" then defaults="--defaults-extra-file=$DATADIR/my.cnf" fi# Next try where the source installs put itelif test -d $MY_BASEDIR_VERSION/var/mysqlthen DATADIR=$MY_BASEDIR_VERSION/var# Or just give up and use our compiled-in defaultelse DATADIR=/usr/local/mysql5./datafiif test -z "$MYSQL_HOME"then if test -r "$MY_BASEDIR_VERSION/my.cnf" && test -r "$DATADIR/my.cnf" then log_error "WARNING: Found two instances of my.cnf -$MY_BASEDIR_VERSION/my.cnf and$DATADIR/my.cnfIGNORING $DATADIR/my.cnf" MYSQL_HOME=$MY_BASEDIR_VERSION elif test -r "$DATADIR/my.cnf" then log_error "WARNING: Found $DATADIR/my.cnfThe data directory is a deprecated location for my.cnf, please move it to$MY_BASEDIR_VERSION/my.cnf" MYSQL_HOME=$DATADIR else MYSQL_HOME=$MY_BASEDIR_VERSION fifiexport MYSQL_HOME# Get first arguments from the my.cnf file, groups [mysqld] and [mysqld_safe]# and then merge with the command line arguments##从my.cnf文件中取得参数 组[mysqld]和[mysqld-safe]if test -x "$MY_BASEDIR_VERSION/bin/my_print_defaults"then print_defaults="$MY_BASEDIR_VERSION/bin/my_print_defaults"elif test -x `dirname $0`/my_print_defaultsthen print_defaults="`dirname $0`/my_print_defaults"elif test -x ./bin/my_print_defaultsthen print_defaults="./bin/my_print_defaults"elif test -x /usr/local/mysql5./bin/my_print_defaultsthen print_defaults="/usr/local/mysql5./bin/my_print_defaults"elif test -x /usr/local/mysql5./bin/mysql_print_defaultsthen print_defaults="/usr/local/mysql5./bin/mysql_print_defaults"else print_defaults="my_print_defaults"fiappend_arg_to_args () { args="$args "`shell_quote_string "$1"`}args=SET_USER=2parse_arguments `$print_defaults $defaults --loose-verbose mysqld server`if test $SET_USER -eq 2then SET_USER=0fiparse_arguments `$print_defaults $defaults --loose-verbose mysqld_safe safe_mysqld`parse_arguments PICK-ARGS-FROM-ARGV "$@"## Try to find the plugin directory## Use user-supplied argumentif [ -n "${PLUGIN_DIR}" ]; then plugin_dir="${PLUGIN_DIR}"else # Try to find plugin dir relative to basedir for dir in lib/mysql/plugin lib/plugin do if [ -d "${MY_BASEDIR_VERSION}/${dir}" ]; then plugin_dir="${MY_BASEDIR_VERSION}/${dir}" break fi done # Give up and use compiled-in default if [ -z "${plugin_dir}" ]; then plugin_dir='/usr/local/mysql5./lib/plugin' fifiplugin_dir="${plugin_dir}${PLUGIN_VARIANT}"# Determine what logging facility to use# Ensure that 'logger' exists, if it's requestedif [ $want_syslog -eq 1 ]then my_which logger > /dev/null 2>&1 if [ $? -ne 0 ] then log_error "--syslog requested, but no 'logger' program found. Please ensure that 'logger' is in your PATH, or do not specify the --syslog option to mysqld_safe." exit 1 fifiif [ -n "$err_log" -o $want_syslog -eq 0 ]then if [ -n "$err_log" ] then # mysqld adds ".err" if there is no extension on the --log-error # argument; must match that here, or mysqld_safe will write to a # different log file than mysqld # mysqld does not add ".err" to "--log-error=foo."; it considers a # trailing "." as an extension if expr "$err_log" : '.*\.[^/]*$' > /dev/null then : else err_log="$err_log".err fi case "$err_log" in /* ) ;; * ) err_log="$DATADIR/$err_log" ;; esac else err_log=$DATADIR/`hostname`.err fi append_arg_to_args "--log-error=$err_log" if [ $want_syslog -eq 1 ] then # User explicitly asked for syslog, so warn that it isn't used log_error "Can't log to error log and syslog at the same time. Remove all --log-error configuration options for --syslog to take effect." fi # Log to err_log file log_notice "Logging to '$err_log'." logging=file if [ ! -f "$err_log" ]; then # if error log already exists, touch "$err_log" # we just append. otherwise, chmod "$fmode" "$err_log" # fix the permissions here! fielse if [ -n "$syslog_tag" ] then # Sanitize the syslog tag syslog_tag=`echo "$syslog_tag" | sed -e 's/[^a-zA-Z0-9_-]/_/g'` syslog_tag_mysqld_safe="${syslog_tag_mysqld_safe}-$syslog_tag" syslog_tag_mysqld="${syslog_tag_mysqld}-$syslog_tag" fi log_notice "Logging to syslog." logging=syslogfiUSER_OPTION=""if test -w / -o "$USER" = "root"then if test "$user" != "root" -o $SET_USER = 1 then USER_OPTION="--user=$user" fi # Change the err log to the right user, if it is in use if [ $want_syslog -eq 0 ]; then touch "$err_log" chown $user "$err_log" fi if test -n "$open_files" then ulimit -n $open_files fifiif test -n "$open_files"then append_arg_to_args "--open-files-limit=$open_files"fisafe_mysql_unix_port=${mysql_unix_port:-${MYSQL_UNIX_PORT:-/tmp/mysql.sock}}# Make sure that directory for $safe_mysql_unix_port existsmysql_unix_port_dir=`dirname $safe_mysql_unix_port`if [ ! -d $mysql_unix_port_dir ]then mkdir $mysql_unix_port_dir chown $user $mysql_unix_port_dir chmod 755 $mysql_unix_port_dirfi# If the user doesn't specify a binary, we assume name "mysqld"if test -z "$MYSQLD"then MYSQLD=mysqldfiif test ! -x "$ledir/$MYSQLD"then log_error "The file $ledir/$MYSQLDdoes not exist or is not executable. Please cd to the mysql installationdirectory and restart this script from there as follows:./bin/mysqld_safe&See http://dev.mysql.com/doc/mysql/en/mysqld-safe.html for more information" exit 1fiif test -z "$pid_file"then pid_file="$DATADIR/`hostname`.pid"else case "$pid_file" in /* ) ;; * ) pid_file="$DATADIR/$pid_file" ;; esacfiappend_arg_to_args "--pid-file=$pid_file"if test -n "$mysql_unix_port"then append_arg_to_args "--socket=$mysql_unix_port"fiif test -n "$mysql_tcp_port"then append_arg_to_args "--port=$mysql_tcp_port"fiif test $niceness -eq 0then NOHUP_NICENESS="nohup"else NOHUP_NICENESS="nohup nice -$niceness"fi# Using nice with no args to get the niceness level is GNU-specific.# This check could be extended for other operating systems (e.g.,# BSD could use "nohup sh -c 'ps -o nice -p $$' | tail -1").# But, it also seems that GNU nohup is the only one which messes# with the priority, so this is okay.if nohup nice > /dev/null 2>&1then normal_niceness=`nice` nohup_niceness=`nohup nice 2>/dev/null` numeric_nice_values=1 for val in $normal_niceness $nohup_niceness do case "$val" in -[0-9] | -[0-9][0-9] | -[0-9][0-9][0-9] | \ [0-9] | [0-9][0-9] | [0-9][0-9][0-9] ) ;; * ) numeric_nice_values=0 ;; esac done if test $numeric_nice_values -eq 1 then nice_value_diff=`expr $nohup_niceness - $normal_niceness` if test $? -eq 0 && test $nice_value_diff -gt 0 && \ nice --$nice_value_diff echo testing > /dev/null 2>&1 then # nohup increases the priority (bad), and we are permitted # to lower the priority with respect to the value the user # might have been given niceness=`expr $niceness - $nice_value_diff` NOHUP_NICENESS="nice -$niceness nohup" fi fielse if nohup echo testing > /dev/null 2>&1 then : else # nohup doesn't work on this system NOHUP_NICENESS="" fifi# Try to set the core file size (even if we aren't root) because many systems# don't specify a hard limit on core file size.if test -n "$core_file_size"then ulimit -c $core_file_sizefi## If there exists an old pid file, check if the daemon is already running# Note: The switches to 'ps' may depend on your operating systemif test -f "$pid_file"then PID=`cat "$pid_file"` if kill -0 $PID > /dev/null 2> /dev/null then if ps wwwp $PID | grep -v mysqld_safe | grep -- $MYSQLD > /dev/null then # The pid contains a mysqld process log_error "A mysqld process already exists" exit 1 fi fi rm -f "$pid_file" if test -f "$pid_file" then log_error "Fatal error: Can't remove the pid file:$pid_filePlease remove it manually and start $0 again;mysqld daemon not started" exit 1 fifi## Uncomment the following lines if you want all tables to be automatically# checked and repaired during startup. You should add sensible key_buffer# and sort_buffer values to my.cnf to improve check performance or require# less disk space.# Alternatively, you can start mysqld with the "myisam-recover" option. See# the manual for details.## echo "Checking tables in $DATADIR"# $MY_BASEDIR_VERSION/bin/myisamchk --silent --force --fast --medium-check $DATADIR/*/*.MYI# $MY_BASEDIR_VERSION/bin/isamchk --silent --force $DATADIR/*/*.ISM# Does this work on all systems?#if type ulimit | grep "shell builtin" > /dev/null#then# ulimit -n 256 > /dev/null 2>&1 # Fix for BSD and FreeBSD systems#ficmd="`mysqld_ld_preload_text`$NOHUP_NICENESS"for i in "$ledir/$MYSQLD" "$defaults" "--basedir=$MY_BASEDIR_VERSION" \ "--datadir=$DATADIR" "--plugin-dir=$plugin_dir" "$USER_OPTION"do cmd="$cmd "`shell_quote_string "$i"`donecmd="$cmd $args"# Avoid 'nohup: ignoring input' warningtest -n "$NOHUP_NICENESS" && cmd="$cmd < /dev/null"log_notice "Starting $MYSQLD daemon with databases from $DATADIR"# variable to track the current number of "fast" (a.k.a. subsecond) restartsfast_restart=0# maximum number of restarts before trottling kicks inmax_fast_restarts=5# flag whether a usable sleep command existshave_sleep=1while truedo rm -f $safe_mysql_unix_port "$pid_file" # Some extra safety start_time=`date +%M%S` eval_log_error "$cmd" if [ $want_syslog -eq 0 -a ! -f "$err_log" ]; then touch "$err_log" # hypothetical: log was renamed but not chown $user "$err_log" # flushed yet. we'd recreate it with chmod "$fmode" "$err_log" # wrong owner next time we log, so set fi # it up correctly while we can! end_time=`date +%M%S` if test ! -f "$pid_file" # This is removed if normal shutdown then break fi # sanity check if time reading is sane and there's sleep if test $end_time -gt 0 -a $have_sleep -gt 0 then # throttle down the fast restarts if test $end_time -eq $start_time then fast_restart=`expr $fast_restart + 1` if test $fast_restart -ge $max_fast_restarts then log_notice "The server is respawning too fast. Sleeping for 1 second." sleep 1 sleep_state=$? if test $sleep_state -gt 0 then log_notice "The server is respawning too fast and no working sleep command. Turning off trottling." have_sleep=0 fi fast_restart=0 fi else fast_restart=0 fi fi if true && test $KILL_MYSQLD -eq 1 then # Test if one process was hanging. # This is only a fix for Linux (running as base 3 mysqld processes) # but should work for the rest of the servers. # The only thing is ps x => redhat 5 gives warnings when using ps -x. # kill -9 is used or the process won't react on the kill. numofproces=`ps xaww | grep -v "grep" | grep "$ledir/$MYSQLD\>" | grep -c "pid-file=$pid_file"` log_notice "Number of processes running now: $numofproces" I=1 while test "$I" -le "$numofproces" do PROC=`ps xaww | grep "$ledir/$MYSQLD\>" | grep -v "grep" | grep "pid-file=$pid_file" | sed -n '$p'` for T in $PROC do break done # echo "TEST $I - $T **" if kill -9 $T then log_error "$MYSQLD process hanging, pid $T - killed" else break fi I=`expr $I + 1` done fi log_notice "mysqld restarted"donelog_notice "mysqld from pid file $pid_file ended" [mysql@master mysql5.6]$ pwd/usr/local/mysql5.6[mysql@master mysql5.6]$ mysqld_safe --defaults-file=/etc/my.cnf --user=mysql 150309 10:35:40 mysqld_safe Logging to '/usr/local/mysql5.6/data/master.err'.150309 10:35:40 mysqld_safe A mysqld process already exists[mysql@master mysql5.6]$ rm /usr/local/mysql5.6/data/master.pid[mysql@master mysql5.6]$ mysqld_safe --defaults-file=/etc/my.cnf --user=mysql 150309 10:35:59 mysqld_safe Logging to '/usr/local/mysql5.6/data/master.err'.150309 10:35:59 mysqld_safe Starting mysqld daemon with databases from /usr/local/mysql5.6/data$cmd is nohup /usr/local/mysql5.6/bin/mysqld --defaults-file=/etc/my.cnf --basedir=/usr/local/mysql5.6 --datadir=/usr/local/mysql5.6/data --plugin-dir=/usr/local/mysql5.6/lib/plugin --log-error=/usr/local/mysql5.6/data/master.err --pid-file=/usr/local/mysql5.6/data/master.pid < /dev/null必须在mysql basedir下执行[mysql@master mysql5.6]$ mysqld_safe 150309 10:36:38 mysqld_safe Logging to '/usr/local/mysql5.6/data/master.err'.150309 10:36:38 mysqld_safe Starting mysqld daemon with databases from /usr/local/mysql5.6/data$cmd is nohup /usr/local/mysql5.6/bin/mysqld --basedir=/usr/local/mysql5.6 --datadir=/usr/local/mysql5.6/data --plugin-dir=/usr/local/mysql5.6/lib/plugin --log-error=/usr/local/mysql5.6/data/master.err --pid-file=/usr/local/mysql5.6/data/master.pid < /dev/null[mysql@master ~]$ mysqld_safe --defaults-file=/etc/my.cnf --user=mysql 150309 10:41:19 mysqld_safe Logging to '/usr/local/mysql5./data/master.err'.touch: cannot touch `/usr/local/mysql5./data/master.err': No such file or directorychmod: cannot access `/usr/local/mysql5./data/master.err': No such file or directory150309 10:41:19 mysqld_safe The file /usr/local/mysql5./bin/mysqlddoes not exist or is not executable. Please cd to the mysql installationdirectory and restart this script from there as follows:./bin/mysqld_safe&See http://dev.mysql.com/doc/mysql/en/mysqld-safe.html for more information/usr/local/mysql5.6/bin/mysqld_safe: line 129: /usr/local/mysql5./data/master.err: No such file or directory[mysql@master bin]$ my_print_defaults my_print_defaults Ver 1.6 for Linux at x86_64This software comes with ABSOLUTELY NO WARRANTY. This is free software,and you are welcome to modify and redistribute it under the GPL licensePrints all arguments that is give to some program using the default filesUsage: my_print_defaults [OPTIONS] groups -c, --config-file=name Deprecated, please use --defaults-file instead. Name of config file to read; if no extension is given, default extension (e.g., .ini or .cnf) will be added -#, --debug[=#] This is a non-debug version. Catch this and exit -c, --defaults-file=name Like --config-file, except: if first option, then read this file only, do not read global or per-user config files; should be the first option -e, --defaults-extra-file=name Read this file after the global config file and before the config file in the users home directory; should be the first option -g, --defaults-group-suffix=name In addition to the given groups, read also groups with this suffix -e, --extra-file=name Deprecated. Synonym for --defaults-extra-file. -n, --no-defaults Ignore reading of default option file(s), except for login file. -l, --login-path=name Path to be read from under the login file. -?, --help Display this help message and exit. -v, --verbose Increase the output level -V, --version Output version information and exit.Default options are read from the following files in the given order:/etc/my.cnf /etc/mysql/my.cnf /usr/local/mysql5./etc/my.cnf ~/.my.cnf Variables (--variable-name=value)and boolean options {FALSE|TRUE} Value (after reading options)--------------------------------- ----------------------------------------config-file mydefaults-file mydefaults-extra-file (No default value)defaults-group-suffix (No default value)extra-file (No default value)login-path (No default value)Example usage:my_print_defaults --defaults-file=example.cnf client mysql默认读取的顺序；/etc/my.cnf /etc/mysql/my.cnf /usr/local/mysql5./etc/my.cnf ~/.my.cnf 给我老师的人工智能教程打call！http://blog.youkuaiyun.com/jiangjunshow
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