#!/bin/bash

# mutex file
#
# Open a mutual exclusion lock on the file, unless another process already owns one.
#
# If the file is already locked by another process, the operation fails.
# This function defines a lock on a file as having a file descriptor open to the file.
# This function uses FD 9 to open a lock on the file.  To release the lock, close FD 9:
# exec 9>&-
#
# From https://stackoverflow.com/questions/185451/quick-and-dirty-way-to-ensure-only-one-instance-of-a-shell-script-is-running-at
mutex() {
    local file=$1 pid pids 

    exec 9>>"$file"
    { pids=$(fuser -f "$file"); } 2>&- 9>&- 
    for pid in $pids; do
        [[ $pid = $$ ]] && continue

        exec 9>&- 
        return 1 # Locked by a pid.
    done 
}

# Check lock
mutex /opt/minecraft/tools/auto_restart/auto_restart.lock || { echo "auto_restart.sh already running." >&2; exit 1; }

# Restart server
while true;do
    if [ `ps -ef | grep server.jar | grep -v grep | wc -l` = 0 ];then
        source /opt/minecraft/tools/start_server.sh >&2
        echo [`date +%Y-%m-%d` `date +%H:%M:%S`]: restart server >&2
    fi
    sleep 5
done

脚本里参考stackoverflow上的大佬加了一把锁，防止这个脚本被执行多次同时产生多个实例。

~/tools/auto_restart/auto_restart_on.sh

#!/bin/bash

LOG_FILE="/opt/minecraft/tools/auto_restart/restart.log"

nohup /opt/minecraft/tools/auto_restart/work.sh > $LOG_FILE 2>&1 &

echo auto restart on, view $LOG_FILE to know more.

#!/bin/bash

kill -9 $(ps -aux | grep work.sh | grep -v grep | awk '{print $2}')

echo auto restart off.