脚本模板

!/bin/bash

NOW_SIZE=
REQUIRE_SIZE=2500
LOG_FILE=/var/log/mem.log
SERVICE_STATUS=0

function check_mem() {
NOW_SIZE=$(free -m | awk '/Mem/{print $4}')
if [[ $NOW_SIZE -le $REQUIRE_SIZE ]]; then

    echo "警告：$(date +%F_%H:%m:%S) 内存低于2.5G, 请尽快查看"
else
    echo "提示：$(date +%F_%H:%m:%S) 现在内存是 ${NOW_SIZE}M"
fi

}

function run_service() {
while [[ $SERVICE_STATUS -eq 1 ]]; do
{
check_mem
} >>$LOG_FILE

    sleep 3
done

exit 0

}

function start_service() {
SERVICE_STATUS=1
run_service
}

function stop_service() {
SERVICE_STATUS=2
}

function main() {
case "$1" in
start)
start_service
;;
stop)
stop_service
;;
*)
echo "Usage: $0 {start|stop}"
exit 1
;;
esac
}

main $1

路径 ： /lib/system/systemd/ 定义自己的服务 xxx.service

:'
[Unit]
Description=Check Memory Script
After=network.target

[Service]
Type=simple
ExecStart=/root/scripts/mem.sh start
ExecStop=/root/scripts/mem.sh stop
Restart=on-failure

[Install]
WantedBy=multi-user.target
'