Centos7 rc.loca添加自啓動不生效的問題
背景：
我自己寫了一個mongodb啓動的shell腳本startMongoDB.sh
cat /opt/mongodb/bin/startMongoDB.sh #內容如下
/#!/bin/bash
mongod --config /opt/mongodb/mongodb.conf
然後在/etc/rc.d/rc.local中添加了啓動項（如果是Unbuntu系統，則自己在/etc/init.d/目錄下創建自啓動腳本）
重啓後發現無法啓動，腳本內容如下：
# cat /etc/rc.d/rc.local
#!/bin/bash
# THIS FILE IS ADDED FOR COMPATIBILITY PURPOSES
#
# It is highly advisable to create own systemd services or udev rules
# to run scripts during boot instead of using this file.
#
# In contrast to previous versions due to parallel execution during boot
# this script will NOT be run after all other services.
#
# Please note that you must run 'chmod +x /etc/rc.d/rc.local' to ensure
# that this script will be executed during boot.
touch /var/lock/subsys/local
/opt/mongodb/bin/startMongoDB.sh
嘗試逐步排查下列可能導致啓動失敗的情況
rc.loca權限是否滿足
# ls -l /etc/rc.d/rc.local
-rw-r--r--. 1 root root 523 Jun 11 00:45 /etc/rc.d/rc.local
如果沒有執行權限，需要增加執行權限
# chmod u+x rc.local
-rwxr--r--. 1 root root 523 Jun 11 00:45 rc.local
reboot發現重啓仍然沒有生效
查看系統日誌看能否找到錯誤信息
cat /var/log/message | grep rc.local
找到相關錯誤信息
Jun 11 02:56:36 localhost systemd: Starting /etc/rc.d/rc.local Compatibility...
Jun 11 02:56:36 localhost rc.local: /opt/mongodb/bin/startMongo.sh: line 3: mongod: command not found
Jun 11 02:56:36 localhost systemd: rc-local.service: control process exited, code=exited status=127
原因找到了，日誌提示 mongod 命令無法識別。
修改startMongo.sh腳本，啓動命令mongod改爲使用絕對路徑“/opt/mongodb/bin/mongod”：
vi /opt/mongodb/bin/startMongoDB.sh
/#!/bin/bash
/opt/mongodb/bin/mongod --config /opt/mongodb/mongodb.conf
reboot重啓，問題解決。