今天在centOS 7下更改完靜態ip後發現network服務重啓不了，翻遍了網絡，嘗試了各種方法，終於解決了。
現把各種解決方法歸納整理，希望能讓後面的同學少走點歪路。。。
首先看問題：執行service network restart命令後出現下面的錯誤：
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Restarting network (via systemctl): Job for network.service failed because the control process exited with error code. -
See "systemctl status network.service" and "journalctl -xe" for details. [失敗]
根據提示輸入systemctl status network.service命令後出現如下錯誤信息：
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● network.service - LSB: Bring up/down networking -
Loaded: loaded (/etc/rc.d/init.d/network; bad; vendor preset: disabled) -
Active: failed (Result: exit-code) since 五 2017-07-14 19:01:47 CST; 1min 16s ago -
Docs: man:systemd-sysv-generator(8) -
Process: 4681 ExecStart=/etc/rc.d/init.d/network start (code=exited, status=1/FAILURE) -
CGroup: /system.slice/network.service -
└─1192 /sbin/dhclient -H mini1 -1 -q -lf /var/lib/dhclient/dhclient--ens33.lease -pf /v... -
7月 14 19:01:47 mini1 network[4681]: RTNETLINK answers: File exists -
7月 14 19:01:47 mini1 network[4681]: RTNETLINK answers: File exists -
7月 14 19:01:47 mini1 network[4681]: RTNETLINK answers: File exists -
7月 14 19:01:47 mini1 network[4681]: RTNETLINK answers: File exists -
7月 14 19:01:47 mini1 network[4681]: RTNETLINK answers: File exists -
7月 14 19:01:47 mini1 network[4681]: RTNETLINK answers: File exists -
7月 14 19:01:47 mini1 systemd[1]: network.service: control process exited, code=exited status=1 -
7月 14 19:01:47 mini1 systemd[1]: Failed to start LSB: Bring up/down networking. -
7月 14 19:01:47 mini1 systemd[1]: Unit network.service entered failed state. -
7月 14 19:01:47 mini1 systemd[1]: network.service failed.
network服務啓動不了首先保證/etc/sysconfig/network-scripts目錄下的ifcfg-xxx（每臺機器不一定相同）沒有錯誤（如果你改動過的話），這裏的錯誤指的在更改過程中因爲手誤敲錯字母之類的。
網上最常見的幾種做法如下：
1.和 NetworkManager 服務有衝突，這個好解決，直接關閉 NetworkManger 服務就好了， service NetworkManager stop，並且禁止開機啓動 chkconfig NetworkManager off 。之後重啓就好了。
2和配置文件的MAC地址不匹配，這個也好解決，使用ip addr（或ifconfig）查看mac地址
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1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1 -
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 -
inet 127.0.0.1/8 scope host lo -
valid_lft forever preferred_lft forever -
inet6 ::1/128 scope host -
valid_lft forever preferred_lft forever -
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 -
link/ether 00:0c:29:b8:e7:21 brd ff:ff:ff:ff:ff:ff -
inet 192.168.65.141/24 brd 192.168.65.255 scope global dynamic ens33 -
valid_lft 1193sec preferred_lft 1193sec -
inet6 fe80::cca2:d835:f93:e637/64 scope link -
valid_lft forever preferred_lft forever
00:0c:29:b8:e7:21這個就是MAC地址了，將/etc/sysconfig/network-scripts/ifcfg-xxx中的HWADDR（如果沒有就添加上）改成這個MAC地址
3.設定開機啓動一個名爲NetworkManager-wait-online服務，命令爲：
systemctl enable NetworkManager-wait-online.service