systemd

chkconfig –level 3 httpd on	systemctl enable httpd.service
chkconfig –level 3 httpd off	systemctl disable httpd.service
service httpd status	systemctl status httpd.service
service httpd start	systemctl start httpd.service
service httpd stop	systemctl stop httpd.service
service httpd restart	systemctl restart httpd.service
chkconfig –list	systemctl list-units –type=service

systemctl list-units --type=service
systemctl list-unit-files

for i in `systemctl list-unit-files  | grep enabled | grep abrt | cut -d ‘ ‘ -f 1`; do
 systemctl disable $i;
done

systemctl disable sshd
systemctl disable postfix
systemctl disable bluetooth

/etc/inittab
5 ==> 3
sudo systemctl set-default multi-user.target
sudo systemctl set-default graphical.target

/usr/lib/systemd/system/: 存放 unit 的文件
/etc/systemd/system/: 开机执行的文件

systemctl disable postfix

rm ‘/etc/systemd/system/multi-user.target.wants/postfix.service‘

systemctl enable sshd

ln -s ‘/usr/lib/systemd/system/sshd.service‘ ‘/etc/systemd/system/multi-user.target.wants/sshd.service‘

cat /usr/lib/systemd/system/postfix.service

[Unit]
Description=Postfix Mail Transport Agent
After=syslog.target network.target
Conflicts=sendmail.service exim.service
[Service]
Type=forking
PIDFile=/var/spool/postfix/pid/master.pid
EnvironmentFile=-/etc/sysconfig/network
ExecStartPre=-/usr/libexec/postfix/aliasesdb
ExecStartPre=-/usr/libexec/postfix/chroot-update
ExecStart=/usr/sbin/postfix start
ExecReload=/usr/sbin/postfix reload
ExecStop=/usr/sbin/postfix stop
[Install]
WantedBy=multi-user.target