關閉或啟用 CentOS 7 上的 Service

以 postfix 為例
關閉 postfix
# service postfix stop
Redirecting to /bin/systemctl stop  postfix.service

預設不啟用 postfix
# chkconfig postfix off
注意：正在轉送請求至「systemctl disable postfix.service」。
rm '/etc/systemd/system/multi-user.target.wants/postfix.service'

啟動 postfix
# service postfix start
Redirecting to /bin/systemctl start  postfix.service

預設啟用 postfix
# chkconfig postfix on
注意：正在轉送請求至「systemctl enable postfix.service」。
ln -s '/usr/lib/systemd/system/postfix.service' '/etc/systemd/system/multi-user.target.wants/postfix.service'
由上面可以發現 CentOS 7.x 和之前的 CentOS 6.x/5.x 處理方式有些不同

使用 service 時已經改用 systemctl 來做處理
使用 chkconfig 時，是把在 /usr/lib/systemd/system 目錄下的 service 服務名稱 在/etc/systemd/system/multi-user.target.wants 目錄之下做建立連結或刪除連結

直接使用 systemctl 來做處理

啟動 postfix
# systemctl start postfix
# systemctl start postfix.service

關閉 postfix
# systemctl stop postfix
# systemctl stop postfix.service

預設啟用 postfix
# systemctl enable postfix
# systemctl enable postfix.service
ln -s '/usr/lib/systemd/system/postfix.service' '/etc/systemd/system/multi-user.target.wants/postfix.service'

預設不啟用 postfix
# systemctl disable postfix
rm '/etc/systemd/system/multi-user.target.wants/postfix.service'
# systemctl disable postfix.service
rm '/etc/systemd/system/multi-user.target.wants/postfix.service'

列出所有 service 的啟用狀態
# systemctl list-unit-files
UNIT FILE                                   STATE
proc-sys-fs-binfmt_misc.automount           static
dev-hugepages.mount                         static
dev-mqueue.mount                            static
proc-fs-nfsd.mount                          static
proc-sys-fs-binfmt_misc.mount               static
sys-fs-fuse-connections.mount               static
sys-kernel-config.mount                     static
sys-kernel-debug.mount                      static
tmp.mount                                   disabled
var-lib-nfs-rpc_pipefs.mount                static
brandbot.path                               disabled
systemd-ask-password-console.path           static
systemd-ask-password-plymouth.path          static
systemd-ask-password-wall.path              static
session-1.scope                             static
session-2.scope                             static
session-4.scope                             static
abrt-ccpp.service                           enabled
abrt-oops.service                           enabled
abrt-pstoreoops.service                     disabled
abrt-vmcore.service                         enabled
abrt-xorg.service                           enabled
abrtd.service                               enabled
arp-ethers.service                          disabled
atd.service                                 enabled
auditd.service                              enabled
autovt@.service                             disabled