文件操作 - mysqld_safe

文件: /usr/bin/mysqld_safe

编辑文件内容

#!/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
#
# Script to start the MySQL daemon and restart it if it dies unexpectedly
#
# 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

# Initialize script globals
KILL_MYSQLD=1;
MYSQLD=
niceness=0
mysqld_ld_preload=
mysqld_ld_library_path=

# Initial logging status: error log is not open, and not using syslog
logging=init
want_syslog=0
syslog_tag=
user='mysql'
pid_file=
pid_file_append=
err_log=
err_log_append=
timestamp_format=UTC

syslog_tag_mysqld=mysqld
syslog_tag_mysqld_safe=mysqld_safe
syslog_facility=daemon

trap '' 1 2 3 15			# we shouldn't let anyone kill us
trap '' 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.
umask 007                               # fallback
UMASK="${UMASK-0640}"
fmode=`echo "$UMASK" | sed -e 's/[^0246]//g'`
octalp=`echo "$fmode"|cut -c1`
fmlen=`echo "$fmode"|wc -c|sed -e 's/ //g'`
if [ "x$octalp" != "x0" -o "x$UMASK" != "x$fmode" -o "x$fmlen" != "x5" ]
then
  fmode=0640
  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." >&2
fi
fmode=`echo "$fmode"|cut -c3-4`
fmode="6$fmode"
if [ "x$UMASK" != "x0$fmode" ]
then
  echo "UMASK corrected from $UMASK to 0$fmode ..."
fi

defaults=
case "$1" in
    --no-defaults|--defaults-file=*|--defaults-extra-file=*)
      defaults="$1"; shift
      ;;
esac

usage () {
        cat <<EOF
Usage: $0 [OPTIONS]
 The following options may be given as the first argument:
  --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

Other options:
  --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'
  --mysqld-safe-log-         TYPE must be one of UTC (ISO 8601 UTC),
    timestamps=TYPE          system (ISO 8601 local time), hyphen
                             (hyphenated date a la mysqld 5.6), legacy
                             (legacy non-ISO 8601 mysqld_safe timestamps)

All other options are passed to the mysqld program.

EOF
        exit 1
}

my_which ()
{
  save_ifs="${IFS-UNSET}"
  IFS=:
  ret=0
  for file
  do
    for dir in $PATH
    do
      if [ -f "$dir/$file" ]
      then
        echo "$dir/$file"
        continue 2
      fi
    done

ret=1  #signal an error
	break
  done

if [ "$save_ifs" = UNSET ]
  then
    unset IFS
  else
    IFS="$save_ifs"
  fi
  return $ret  # Success
}

log_generic () {
  priority="$1"
  shift

msg="`eval $DATE` mysqld_safe $*"
  echo "$msg"
  case $logging in
    init) ;;  # Just echo the message, don't save it anywhere
    file)
      if [ -w / -o "$USER" = "root" ]; then
        true
      else
        echo "$msg" >> "$err_log"
      fi
      ;;
    syslog) logger -t "$syslog_tag_mysqld_safe" -p "$priority" "$*" ;;
    both)
      if [ -w / -o "$USER" = "root" ]; then
        true
      else
        echo "$msg" >> "$err_log"
      fi
      logger -t "$syslog_tag_mysqld_safe" -p "$priority" "$*"
      ;;
    *)
      echo "Internal program error (non-fatal):" \
           " unknown logging method '$logging'" >&2
      ;;
  esac
}

log_error () {
  log_generic ${syslog_facility}.error "$@" >&2
}

log_notice () {
  log_generic ${syslog_facility}.notice "$@"
}

eval_log_error () {
  cmd="$1"
  case $logging in
    file)
      if [ -w / -o "$USER" = "root" ]; then
        cmd="$cmd > /dev/null 2>&1"
      else
        cmd="$cmd >> "`shell_quote_string "$err_log"`" 2>&1"
      fi
      ;;
    syslog)
      cmd="$cmd --log-syslog=1 --log-syslog-facility=$syslog_facility '--log-syslog-tag=$syslog_tag' > /dev/null 2>&1"
      ;;
    both)
      if [ -w / -o "$USER" = "root" ]; then
        cmd="$cmd --log-syslog=1 --log-syslog-facility=$syslog_facility '--log-syslog-tag=$syslog_tag' > /dev/null 2>&1"
      else
        cmd="$cmd --log-syslog=1 --log-syslog-facility=$syslog_facility '--log-syslog-tag=$syslog_tag' >> "`shell_quote_string "$err_log"`" 2>&1"
      fi
      ;;
    *)
      echo "Internal program error (non-fatal):" \
           " unknown logging method '$logging'" >&2
      ;;
  esac

#echo "Running mysqld: [$cmd]"
  cmd="env MYSQLD_PARENT_PID=$$ $cmd"
  eval "$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'
}

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.
  pick_args=
  if test "$1" = PICK-ARGS-FROM-ARGV
  then
    pick_args=1
    shift
  fi

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
      # these get passed explicitly to mysqld
      --basedir=*) MY_BASEDIR_VERSION="$val" ;;
      --datadir=*)
        case $val in
          /) DATADIR=$val ;;
          *) DATADIR="`echo $val | sed 's;/*$;;'`" ;;
        esac
        ;;
      --pid-file=*) pid_file="$val" ;;
      --plugin-dir=*) PLUGIN_DIR="$val" ;;
      --user=*) user="$val"; SET_USER=1 ;;

# these might have been set in a [mysqld_safe] section of my.cnf
      # they are added to mysqld command line to override settings from my.cnf
      --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])!
      --core-file-size=*) core_file_size="$val" ;;
      --ledir=*)
        if [ -z "$pick_args" ]; then
          log_error "--ledir option can only be used as command line option, found in config file"
          exit 1
        fi
        ledir="$val"
        ;;
      --malloc-lib=*) set_malloc_lib "$val" ;;
      --mysqld=*)
        if [ -z "$pick_args" ]; then
          log_error "--mysqld option can only be used as command line option, found in config file"
          exit 1
        fi
        MYSQLD="$val" ;;
      --mysqld-version=*)
        if [ -z "$pick_args" ]; then
          log_error "--mysqld-version option can only be used as command line option, found in config file"
          exit 1
        fi
        if test -n "$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="$val" ;;
      --skip-kill-mysqld*) KILL_MYSQLD=0 ;;
      --mysqld-safe-log-timestamps=*) timestamp_format="$val" ;;
      --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"
}

# set_malloc_lib LIB
# - If LIB is empty, do nothing and return
# - 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() {
  # This list is kept intentionally simple.
  malloc_dirs="/usr/lib /usr/lib64 /usr/lib/i386-linux-gnu /usr/lib/x86_64-linux-gnu"
  malloc_lib="$1"

# Allow --malloc-lib='' to override other settings
  [ -z  "$malloc_lib" ] && return

case "$malloc_lib" in
    /*)
      if [ ! -r "$malloc_lib" ]; then
        log_error "--malloc-lib can not be read and will not be used"
        exit 1
      fi

# Restrict to a the list in $malloc_dirs above
      case "`dirname "$malloc_lib"`" in
        /usr/lib) ;;
        /usr/lib64) ;;
        /usr/lib/i386-linux-gnu) ;;
        /usr/lib/x86_64-linux-gnu) ;;
        *)
          log_error "--malloc-lib must be located in one of the directories: $malloc_dirs"
          exit 1
          ;;
      esac
      ;;
    *)
      log_error "--malloc-lib must be an absolute path ignoring value '$malloc_lib'"
      exit 1
      ;;
  esac

add_mysqld_ld_preload "$malloc_lib"
}

find_basedir_from_cmdline () {
  for arg in "$@"; do
    case $arg in
      --basedir=*)
        MY_BASEDIR_VERSION="`echo "$arg" | sed -e 's;^--[^=]*=;;'`"
        # Convert to full path
        cd "$MY_BASEDIR_VERSION"
        if [ $? -ne 0 ] ; then
          log_error "--basedir set to '$MY_BASEDIR_VERSION', however could not access directory"
          exit 1
        fi
        MY_BASEDIR_VERSION="`pwd`"
        ;;
    esac
  done
}

#
# First, try to find BASEDIR and ledir (where mysqld is)
#

oldpwd="`pwd`"

# Args not parsed yet, check if --basedir was given on command line
find_basedir_from_cmdline "$@"

# --basedir is already overridden on command line
if test -n "$MY_BASEDIR_VERSION" -a -d "$MY_BASEDIR_VERSION" ; then
  # Search for mysqld and set ledir
  for dir in sbin libexec sbin bin ; do
    if test -x "$MY_BASEDIR_VERSION/$dir/mysqld" ; then
      ledir="$MY_BASEDIR_VERSION/$dir"
      break
    fi
  done

else
  # Basedir should be parent dir of bindir, unless some non-standard
  # layout is used

cd "`dirname $0`"
  if [ -h "$0" ] ; then
    realpath="`ls -l  "$0" | awk '{print $NF}'`"
    cd "`dirname "$realpath"`"
  fi
  cd ..
  MY_PWD="`pwd`"

# Search for mysqld and set ledir and BASEDIR
  for dir in sbin libexec sbin bin ; do
    if test -x "$MY_PWD/$dir/mysqld" ; then
      MY_BASEDIR_VERSION="$MY_PWD"
      ledir="$MY_BASEDIR_VERSION/$dir"
      break
    fi
  done

# If we still didn't find anything, use the compiled-in defaults
  if test -z "$MY_BASEDIR_VERSION" ; then
    MY_BASEDIR_VERSION='/usr'
    ledir='/usr/sbin'
  fi
fi

#
# Second, try to find the data directory
#

# Try where the binary installs put it
if test -d $MY_BASEDIR_VERSION/data/mysql
then
  DATADIR=$MY_BASEDIR_VERSION/data
# Or just give up and use our compiled-in default
else
  DATADIR=/var/lib/mysql
fi

if test -z "$MYSQL_HOME"
then 
  MYSQL_HOME=$MY_BASEDIR_VERSION
fi
export MYSQL_HOME

# Get first arguments from the my.cnf file, groups [mysqld] and [mysqld_safe]
# and then merge with the command line arguments
if test -x "$MY_BASEDIR_VERSION/bin/my_print_defaults" ; then
  print_defaults="$MY_BASEDIR_VERSION/bin/my_print_defaults"
elif test -x "/usr/bin/my_print_defaults" ; then
  print_defaults="/usr/bin/my_print_defaults"
else
  print_defaults="my_print_defaults"
fi

append_arg_to_args () {
  args="$args "`shell_quote_string "$1"`
}

args=

cd "$oldpwd"

SET_USER=2
parse_arguments `$print_defaults $defaults --loose-verbose mysqld server`
if test $SET_USER -eq 2
then
  SET_USER=0
fi

parse_arguments `$print_defaults $defaults --loose-verbose mysqld_safe safe_mysqld`
parse_arguments PICK-ARGS-FROM-ARGV "$@"

#
# Sort out date command from $timestamp_format early so we'll start off
# with correct log messages.
#
case "$timestamp_format" in
    UTC|utc)       DATE="date -u +%Y-%m-%dT%H:%M:%S.%06NZ";;
    SYSTEM|system) DATE="date +%Y-%m-%dT%H:%M:%S.%06N%:z";;
    HYPHEN|hyphen) DATE="date +'%Y-%m-%d %H:%M:%S'";;
    LEGACY|legacy) DATE="date +'%y%m%d %H:%M:%S'";;
    *)             DATE="date -u +%Y-%m-%dT%H:%M:%S.%06NZ";
                   log_error "unknown data format $timestamp_format, using UTC";;
esac

#
# Try to find the plugin directory
#

# Use user-supplied argument
if [ -n "${PLUGIN_DIR}" ]; then
  plugin_dir="${PLUGIN_DIR}"
else
  # Try to find plugin dir relative to basedir
  for dir in lib64/mysql/plugin lib64/plugin 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 "${plugin_dir}" ]; then
    plugin_dir='/usr/lib/mysql/plugin'
  fi
fi
plugin_dir="${plugin_dir}${PLUGIN_VARIANT}"

# Determine what logging facility to use

# Ensure that 'logger' exists, if it's requested
if [ $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
  fi
fi

if [ $want_syslog -eq 1 ]
then
  if [ -n "$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=syslog
fi

if [ -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

err_log_append="$err_log"
    case "$err_log" in
      /* ) ;;
      ./*|../*)
          # Preparing absolute path from the relative path value specified for the
          # --log-error argument.
          #
          # Absolute path will be prepared for the value of following form
          #    ./bar/foo OR
          #   ../old_bar/foo
          # for --log-error argument.
          #
          # Note: If directory of log file name does not exists or
          #       if write or execute permissions are missing on directory then
          #       --log-error is set  $DATADIR/`hostname`.err

log_dir_name="$(dirname "$err_log")";
          if [ ! -d "$log_dir_name" ]
          then
            log_notice "Directory "$log_dir_name" does not exists.";
            err_log=$DATADIR/`hostname`.err
          elif [ ! -x "$log_dir_name" -o ! -w "$log_dir_name" ]
          then
            log_notice "Do not have Execute or Write permissions on directory "$log_dir_name".";
            err_log=$DATADIR/`hostname`.err
          else
            err_log=$(cd $log_dir_name && pwd -P)/$(basename "$err_log")
          fi
          ;;
      * ) err_log="$DATADIR/$err_log" ;;
    esac
  else
    err_log=$DATADIR/`hostname`.err
    err_log_append=`hostname`.err
  fi

append_arg_to_args "--log-error=$err_log_append"

if [ $want_syslog -eq 1 ]
  then
    logging=both
  else
    logging=file
  fi
fi

logdir=`dirname "$err_log"`
# Change the err log to the right user, if possible and it is in use
if [ $logging = "file" -o $logging = "both" ]; then
  if [ ! -e "$err_log" -a ! -h "$err_log" ]; then
    if test -w / -o "$USER" = "root"; then
      case $logdir in
        /var/log)
          (
            umask 0137
            set -o noclobber
            > "$err_log" && chown $user "$err_log"
          ) ;;
        *) ;;
      esac
    else
      (
        umask 0137
        set -o noclobber
        > "$err_log"
      )
    fi
  fi

if [ -f "$err_log" -o -p "$err_log" ]; then        # Log to err_log file
    log_notice "Logging to '$err_log'."
  elif [ "x$user" = "xroot" ]; then # running as root, mysqld can create log file; continue
    echo "Logging to '$err_log'." >&2
  else
    case $logdir in
      # We can't create $err_log, however mysqld can; continue
      /tmp|/var/tmp|/var/log/mysql|$DATADIR)
        echo "Logging to '$err_log'." >&2
        ;;
      # We can't create $err_log and don't know if mysqld can; error out
      *)
        log_error "error: log-error set to '$err_log', however file don't exists. Create writable for user '$user'."
        exit 1
        ;;
    esac
  fi
fi

USER_OPTION=""
if test -w / -o "$USER" = "root"
then
  if test "$user" != "root" -o $SET_USER = 1
  then
    USER_OPTION="--user=$user"
  fi
  if test -n "$open_files"
  then
    ulimit -n $open_files
  fi
fi

if test -n "$open_files"
then
  append_arg_to_args "--open-files-limit=$open_files"
fi

safe_mysql_unix_port=${mysql_unix_port:-${MYSQL_UNIX_PORT:-/var/run/mysqld/mysqld.sock}}
# Check that directory for $safe_mysql_unix_port exists
mysql_unix_port_dir=`dirname $safe_mysql_unix_port`
if [ ! -d $mysql_unix_port_dir ]
then
  log_error "Directory '$mysql_unix_port_dir' for UNIX socket file don't exists."
  exit 1
fi

# If the user doesn't specify a binary, we assume name "mysqld"
if test -z "$MYSQLD"
then
  MYSQLD=mysqld
fi

if test ! -x "$ledir/$MYSQLD"
then
  log_error "The file $ledir/$MYSQLD
does not exist or is not executable. Please cd to the mysql installation
directory 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 1
fi

if test -z "$pid_file"
then
  pid_file="$DATADIR/`hostname`.pid"
  pid_file_append="`hostname`.pid"
else
  pid_file_append="$pid_file"
  case "$pid_file" in
    /* ) ;;
    * )  pid_file="$DATADIR/$pid_file" ;;
  esac
fi
append_arg_to_args "--pid-file=$pid_file_append"

if test -n "$mysql_unix_port"
then
  append_arg_to_args "--socket=$mysql_unix_port"
fi
if test -n "$mysql_tcp_port"
then
  append_arg_to_args "--port=$mysql_tcp_port"
fi

if test $niceness -eq 0
then
  NOHUP_NICENESS="nohup"
else
  NOHUP_NICENESS="nohup nice -$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>&1
then
    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
    fi
else
    if nohup echo testing > /dev/null 2>&1
    then
        :
    else
        # nohup doesn't work on this system
        NOHUP_NICENESS=""
    fi
fi

# 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_size
fi

#
# If there exists an old pid file, check if the daemon is already running
# Note: The switches to 'ps' may depend on your operating system
if 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 -- $MYSQLD > /dev/null
    then    # The pid contains a mysqld process
      log_error "A mysqld process already exists"
      exit 1
    fi
  fi
  if [ ! -h "$pid_file" ]; then
      rm -f "$pid_file"
      if test -f "$pid_file"; then
        log_error "Fatal error: Can't remove the pid file:
$pid_file.
Please remove the file manually and start $0 again;
mysqld daemon not started"
        exit 1
      fi
  fi
  if [ ! -h "$safe_mysql_unix_port" ]; then
      rm -f "$safe_mysql_unix_port"
      if test -f "$safe_mysql_unix_port"; then
        log_error "Fatal error: Can't remove the socket file:
$safe_mysql_unix_port.
Please remove the file manually and start $0 again;
mysqld daemon not started"
        exit 1
      fi
  fi
  if [ ! -h "$pid_file.shutdown" ]; then
      rm -f "$pid_file.shutdown"
      if test -f "$pid_file.shutdown"; then
        log_error "Fatal error: Can't remove the shutdown file:
$pid_file.shutdown.
Please remove the file manually and start $0 again;
mysqld daemon not started"
        exit 1
      fi
  fi
fi

#
# 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
#fi

cmd="`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 "$i"`
done
cmd="$cmd $args"
# Avoid 'nohup: ignoring input' warning
test -n "$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) restarts
fast_restart=0
# maximum number of restarts before throttling kicks in
max_fast_restarts=5
# flag whether a usable sleep command exists
have_sleep=1
while true
do
  start_time=`date +%M%S`
  eval_log_error "$cmd"
  if [ $? -eq 16 ] ; then
    dont_restart_mysqld=false
    echo "Restarting mysqld..."
  else
    dont_restart_mysqld=true
  fi

# hypothetical: log was renamed but not
  # flushed yet. we'd recreate it with
  # wrong owner next time we log, so set
  # it up correctly while we can!

if [ $want_syslog -eq 0 -a ! -f "$err_log" -a ! -h "$err_log" ]; then
    if test -w / -o "$USER" = "root"; then
      logdir=`dirname "$err_log"`
      case $logdir in
        /var/log)
          (
            umask 0137
            set -o noclobber
            > "$err_log" && chown $user "$err_log"
          ) ;;
        *) ;;
      esac
    else
      (
        umask 0137
        set -o noclobber
        > "$err_log"
      )
    fi
  fi

end_time=`date +%M%S`

if $dont_restart_mysqld; then
    if test ! -f "$pid_file"		# This is removed if normal shutdown
    then
      break
    else                                  # self's mysqld crashed or other's mysqld running
        PID=`cat "$pid_file"`
        if kill -0 $PID > /dev/null 2> /dev/null
        then                                # true when above pid belongs to a running mysqld process
          log_error "A mysqld process with pid=$PID is already running. Aborting!!"
          exit 1
        fi
    fi
  fi

if test -f "$pid_file.shutdown"	# created to signal that it must stop
  then
    log_notice "$pid_file.shutdown present. The server will not restart."
    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 in addition no working 'sleep' command was found. Turning off throttling."
          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 $I + 1`
    done
  fi
  if [ ! -h "$pid_file" ]; then
    rm -f "$pid_file"
  fi
  if [ ! -h "$safe_mysql_unix_port" ]; then
    rm -f "$safe_mysql_unix_port"
  fi
  if [ ! -h "$pid_file.shutdown" ]; then
    rm -f "$pid_file.shutdown"
  fi
  log_notice "mysqld restarted"
done

if [ ! -h "$pid_file.shutdown" ]; then
  rm -f "$pid_file.shutdown"
fi

log_notice "mysqld from pid file $pid_file ended"

if [ ! -h "$safe_pid" ]; then
  rm -f "$safe_pid"                       # Some Extra Safety. File is deleted
fi                                        # once the mysqld process ends.

文件操作 - mysqld_safe

文件: /usr/bin/mysqld_safe

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