centos7设置服务为开机自启动（以crond.serivce为例）

一、设置crond.service服务为开机自启动

步骤1：查看crond.serivce服务的自启动状态

[root@test_jenkins ~]# 
[root@test_jenkins ~]# systemctl is-enabled crond.service
disabled
[root@test_jenkins ~]# 
[root@test_jenkins ~]#

此时crond.serivce的自启动状态为disabled

步骤2：开启crond.serivce服务自启动

[root@test_jenkins ~]# 
[root@test_jenkins ~]# 
[root@test_jenkins ~]# systemctl enable crond.service
Created symlink from /etc/systemd/system/multi-user.target.wants/crond.service to /usr/lib/systemd/system/crond.service.
[root@test_jenkins ~]# 
[root@test_jenkins ~]# 
[root@test_jenkins ~]# 
[root@test_jenkins ~]# systemctl is-enabled crond.service
enabled
[root@test_jenkins ~]#
[root@test_jenkins ~]# 
[root@test_jenkins ~]# systemctl list-unit-files | grep enable
abrt-ccpp.service                             enabled 
abrt-oops.service                             enabled 
abrt-vmcore.service                           enabled 
abrt-xorg.service                             enabled 
abrtd.service                                 enabled 
auditd.service                                enabled 
autovt@.service                               enabled 
crond.service                                 enabled 
dbus-org.freedesktop.NetworkManager.service   enabled 
dbus-org.freedesktop.nm-dispatcher.service    enabled 
getty@.service                                enabled 
irqbalance.service                            enabled 
lvm2-monitor.service                          enabled 
microcode.service                             enabled 
NetworkManager-dispatcher.service             enabled 
NetworkManager.service                        enabled 
ntpd.service                                  enabled 
postfix.service                               enabled 
rsyslog.service                               enabled 
snmpd.service                                 enabled 
sshd.service                                  enabled 
systemd-readahead-collect.service             enabled 
systemd-readahead-drop.service                enabled 
systemd-readahead-replay.service              enabled 
tuned.service                                 enabled 
xinetd.service                                enabled 
dm-event.socket                               enabled 
lvm2-lvmetad.socket                           enabled 
lvm2-lvmpolld.socket                          enabled 
pcscd.socket                                  enabled 
telnet.socket                                 enabled 
default.target                                enabled 
multi-user.target                             enabled 
remote-fs.target                              enabled 
runlevel2.target                              enabled 
runlevel3.target                              enabled 
runlevel4.target                              enabled

此时crond.serivce的自启动状态为enabled

附：关闭crond.serivce的自启动状态

[root@test_jenkins ~]# 
[root@test_jenkins ~]# 
[root@test_jenkins ~]# systemctl disable crond.service
Removed symlink /etc/systemd/system/multi-user.target.wants/crond.service.
[root@test_jenkins ~]# 
[root@test_jenkins ~]# 
[root@test_jenkins ~]# systemctl is-enabled crond.service
disabled
[root@test_jenkins ~]# 
[root@test_jenkins ~]#

二、开启和关闭crond.service服务

步骤1：查看crond.service的启动状态

[root@test_jenkins ~]# 
[root@test_jenkins ~]# 
[root@test_jenkins ~]# systemctl status crond.service
● crond.service - Command Scheduler
   Loaded: loaded (/usr/lib/systemd/system/crond.service; enabled; vendor preset: enabled)
   Active: inactive (dead) since 六 2017-07-29 14:19:12 CST; 5s ago
  Process: 805 ExecStart=/usr/sbin/crond -n $CRONDARGS (code=exited, status=0/SUCCESS)
 Main PID: 805 (code=exited, status=0/SUCCESS)

7月 28 14:23:31 test_jenkins systemd[1]: Started Command Scheduler.
7月 28 14:23:31 test_jenkins systemd[1]: Starting Command Scheduler...
7月 28 14:23:31 test_jenkins crond[805]: (CRON) INFO (RANDOM_DELAY will be scaled with factor 84% if used.)
7月 28 14:23:31 test_jenkins crond[805]: (CRON) INFO (running with inotify support)
7月 29 14:19:12 test_jenkins systemd[1]: Stopping Command Scheduler...
7月 29 14:19:12 test_jenkins systemd[1]: Stopped Command Scheduler.
[root@test_jenkins ~]# 
[root@test_jenkins ~]# 
[root@test_jenkins ~]#

此处显示crond.service的启动状态为dead

步骤2：开启服务

[root@test_jenkins ~]# 
[root@test_jenkins ~]# 
[root@test_jenkins ~]# systemctl start crond.service
[root@test_jenkins ~]# 
[root@test_jenkins ~]# 
[root@test_jenkins ~]#

再次查看crond.service的启动状态

[root@test_jenkins ~]# 
[root@test_jenkins ~]# 
[root@test_jenkins ~]# systemctl status crond.service
● crond.service - Command Scheduler
   Loaded: loaded (/usr/lib/systemd/system/crond.service; enabled; vendor preset: enabled)
   Active: active (running) since 六 2017-07-29 14:19:56 CST; 3s ago
 Main PID: 8465 (crond)
   CGroup: /system.slice/crond.service
           └─8465 /usr/sbin/crond -n

7月 29 14:19:56 test_jenkins systemd[1]: Started Command Scheduler.
7月 29 14:19:56 test_jenkins systemd[1]: Starting Command Scheduler...
7月 29 14:19:56 test_jenkins crond[8465]: (CRON) INFO (RANDOM_DELAY will be scaled with factor 44% if used.)
7月 29 14:19:56 test_jenkins crond[8465]: (CRON) INFO (running with inotify support)
7月 29 14:19:56 test_jenkins crond[8465]: (CRON) INFO (@reboot jobs will be run at computer's startup.)
[root@test_jenkins ~]# 
[root@test_jenkins ~]#

此处显示crond.service的启动状态为running

centos7设置服务为开机自启动（以crond.serivce为例）

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