ubuntu重新启动网卡

When an application runs in the background, it’s called a service. These are essential to run the system or our software applications. Some of the common services you will find on most of the servers are Apache, MySQL, NGINX, etc. When the system boots up, these services are configured to automatically startup.

当应用程序在后台运行时，称为服务。 这些对于运行系统或我们的软件应用程序至关重要。 在大多数服务器上可以找到的一些常见服务是Apache，MySQL，NGINX等。当系统启动时，这些服务被配置为自动启动。

I am using Ubuntu to host my websites. I also use MySQL to store all my websites data. Sometimes, I perform regular updates and it’s essential to restart these services. In this tutorial, we will learn various ways to start, stop, and restart services in Ubuntu.

我正在使用Ubuntu托管我的网站。 我还使用MySQL存储所有网站数据。 有时，我会执行定期更新，因此必须重新启动这些服务。 在本教程中，我们将学习在Ubuntu中启动，停止和重新启动服务的各种方法。

在Ubuntu上启动，停止，重新启动服务的不同方法 (Different Ways to Start, Stop, Restart Services on Ubuntu)

1. systemctl command
   systemctl命令
2. service command
   服务命令
3. init scripts
   初始化脚本

使用systemctl启动，停止和重新启动Ubuntu服务 (Using systemctl to start, stop, and restart Ubuntu services)

This is the preferred way to manage Ubuntu services. If you are not sure of the service name, you can run systemctl --all command to list all the services. But, there might be hundreds of services running, so it’s better to filter the list using the grep command.

这是管理Ubuntu服务的首选方法。 如果不确定服务名称，可以运行systemctl --all命令列出所有服务。 但是，可能有数百个服务正在运行，因此最好使用grep命令过滤列表。

Let’s try to find out the service names of MySQL and Apache HTTP server.

让我们尝试找出MySQL和Apache HTTP服务器的服务名称。

# systemctl --all | grep -i mysql
  mysql.service                                                                          loaded    active   running   MySQL Community Server                                                       
# systemctl --all | grep -i apache
  apache2.service                                                                        loaded    active   running   The Apache HTTP Server                                                       
# 

So, the MySQL service name is “mysql.service” and Apache HTTP server service name is “apache2.service”.

因此，MySQL服务名称为“ mysql.service”，而Apache HTTP服务器服务名称为“ apache2.service”。

Let’s learn how to manage these services using the systemctl command.

让我们学习如何使用systemctl命令管理这些服务。

1.使用systemctl停止服务 (1. Stop service using systemctl)

# systemctl stop mysql.service 
#

The command doesn’t give any output if the execution is successful.

如果执行成功，该命令将不提供任何输出。

2.使用systemctl检查服务状态 (2. Checking Service Status using systemctl)

We can check the service status using the below command.

我们可以使用以下命令检查服务状态。

# systemctl status mysql.service 
● mysql.service - MySQL Community Server
   Loaded: loaded (/lib/systemd/system/mysql.service; enabled; vendor preset: enabled)
   Active: inactive (dead) since Sat 2020-05-02 17:39:22 UTC; 9s ago
 Main PID: 26948 (code=exited, status=0/SUCCESS)

3.使用systemctl启动服务 (3. Start service using systemctl)

# systemctl start mysql.service 
# 
# systemctl status mysql.service 
● mysql.service - MySQL Community Server
   Loaded: loaded (/lib/systemd/system/mysql.service; enabled; vendor preset: enabled)
   Active: active (running) since Sat 2020-05-02 17:41:43 UTC; 3s ago
  Process: 30254 ExecStart=/usr/sbin/mysqld --daemonize --pid-file=/run/mysqld/mysqld.pid (code=exited, s
  Process: 30233 ExecStartPre=/usr/share/mysql/mysql-systemd-start pre (code=exited, status=0/SUCCESS)
 Main PID: 30256 (mysqld)
    Tasks: 27 (limit: 2318)
   CGroup: /system.slice/mysql.service
           └─30256 /usr/sbin/mysqld --daemonize --pid-file=/run/mysqld/mysqld.pid

Notice that when we had stopped the service, the “Active” value was inactive (dead). After starting the service, it’s changed to active (running).

请注意，当我们停止服务时，“活动”值处于非活动状态（无效）。 启动服务后，它已更改为活动（运行）。

4.使用systemctl重新启动服务 (4. Restart service using systemctl)

# systemctl restart apache2.service
# systemctl status apache2.service 
● apache2.service - The Apache HTTP Server
   Loaded: loaded (/lib/systemd/system/apache2.service; enabled; vendor preset: enabled)
  Drop-In: /lib/systemd/system/apache2.service.d
           └─apache2-systemd.conf
   Active: active (running) since Sat 2020-05-02 17:55:09 UTC; 8s ago

Tip: It’s not required to use the complete service name with the systemctl command. For example, if we run “systemctl restart mysql” then it will automatically append “.service” to it and execute “systemctl restart mysql.service” command.

提示 ：不需要在systemctl命令中使用完整的服务名称。 例如，如果我们运行“ systemctl restart mysql”，它将自动向其附加“ .service”并执行“ systemctl restart mysql.service”命令。

使用service命令管理Ubuntu服务 (Manage Ubuntu Services using service Command)

We can list all the services using service --status-all command. If needed, use the grep command to filter out the service you are looking for.

我们可以使用service --status-all命令列出所有服务。 如果需要，请使用grep命令过滤出您要查找的服务。

# service --status-all | grep mysql
 [ + ]  mysql
#

In the service command, we have to first specify the service name and then the command to execute.

在service命令中，我们必须首先指定服务名称，然后指定要执行的命令。

Stop a Service:

停止服务：

# service mysql stop

Start a Service:

启动服务：

# service mysql start

Restart a Service:

重新启动服务：

# service mysql restart

Checking Service Status:

检查服务状态：

# service mysql status
● mysql.service - MySQL Community Server
   Loaded: loaded (/lib/systemd/system/mysql.service; enabled; vendor preset: enabled)
   Active: active (running) since Sat 2020-05-02 18:19:34 UTC; 39s ago
  Process: 31768 ExecStart=/usr/sbin/mysqld --daemonize --pid-file=/run/mysqld/mysqld.pid (code=exited, s
  Process: 31746 ExecStartPre=/usr/share/mysql/mysql-systemd-start pre (code=exited, status=0/SUCCESS)
 Main PID: 31770 (mysqld)
    Tasks: 27 (limit: 2318)
   CGroup: /system.slice/mysql.service
           └─31770 /usr/sbin/mysqld --daemonize --pid-file=/run/mysqld/mysqld.pid

Ubuntu初始化脚本来管理服务 (Ubuntu init scripts to Manage Services)

The services init scripts are located in /etc/init.d/ directory. We can use these scripts to manage the services. However, it’s not recommended to use them anymore and it’s better to use the systemctl command.

服务初始化脚本位于/etc/init.d/目录中。 我们可以使用这些脚本来管理服务。 但是，不建议再使用它们，最好使用systemctl命令。

Stop a Service:

停止服务：

# /etc/init.d/mysql stop
[ ok ] Stopping mysql (via systemctl): mysql.service.
#

Start a Service:

启动服务：

# /etc/init.d/mysql start
[ ok ] Starting mysql (via systemctl): mysql.service.
#

Restart a Service:

重新启动服务：

# /etc/init.d/mysql restart
[ ok ] Restarting mysql (via systemctl): mysql.service.
#

Checking Service Status:

检查服务状态：

# /etc/init.d/mysql status
● mysql.service - MySQL Community Server
   Loaded: loaded (/lib/systemd/system/mysql.service; enabled; vendor preset: enabled)
   Active: active (running) since Sat 2020-05-02 18:26:30 UTC; 17s ago

启动/停止服务时的权限问题 (Permission issues when starting/stopping services)

If you are not logged in as root user, the above commands will ask you to provide root user password to execute. If the wrong password is entered, the authentication failed error will be thrown and command will not be executed.

如果您未以root用户身份登录，则上述命令将要求您提供root用户密码才能执行。 如果输入了错误的密码，将抛出认证失败错误，并且将不执行命令。

If you are on the sudoers list, you can run these commands as a sudo user. If you are not on the sudoers list, an error message will be displayed that you are not on the sudoers list and the incident will be reported.

如果您在sudoers列表中，则可以以sudo用户身份运行这些命令。 如果您不在sudoers列表中，则会显示一条错误消息，指出您不在sudoers列表中，并且将报告该事件。

test@localhost:~$ systemctl stop mysql
==== AUTHENTICATING FOR org.freedesktop.systemd1.manage-units ===
Authentication is required to stop 'mysql.service'.
Authenticating as: root
Password: 
polkit-agent-helper-1: pam_authenticate failed: Authentication failure
==== AUTHENTICATION FAILED ===
Failed to stop mysql.service: Access denied
See system logs and 'systemctl status mysql.service' for details.
test@localhost:~$ sudo systemctl stop mysql
[sudo] password for test: 
test is not in the sudoers file.  This incident will be reported.
test@localhost:~$ 

So if you want to manage any service, make sure you have necessary privileges to execute these commands.

因此，如果要管理任何服务，请确保您具有执行这些命令所需的特权。

结论 (Conclusion)

We learned various ways to manage services on Ubuntu. The systemctl command is the preferred approach to start/stop/restart services on Ubuntu. However, the init scripts print the command status, which can be useful in shell scripts to run them and immediately get the status of the command.

我们了解了在Ubuntu上管理服务的各种方法。 systemctl命令是在Ubuntu上启动/停止/重新启动服务的首选方法。 但是，init脚本会打印命令状态，这在shell脚本中运行它们并立即获取命令状态很有用。

翻译自: https://www.journaldev.com/39332/ubuntu-start-stop-restart-services

ubuntu重新启动网卡