How to start nginx linux

CommandLine¶

This page shows you how to start NGINX, and once it’s running, how to control it so that it will stop or restart.

Starting NGINX¶

NGINX is invoked from the command line, usually from /usr/bin/nginx .

Basic Example of Starting NGINX¶

Advanced Example of Starting NGINX¶

/usr/bin/nginx -t -c ~/mynginx.conf -g "pid /var/run/nginx.pid; worker_processes 2;" 

Options¶

-?, -h	Print help.
-v	Print version.
-V	Print NGINX version, compiler version and configure parameters.
-t	Don’t run, just test the configuration file. NGINX checks configuration for correct syntax and then try to open files referred in configuration.
-q	Suppress non-error messages during configuration testing.
-s signal	Send signal to a master process: stop, quit, reopen, reload. (version >= 0.7.53)
-p prefix	Set prefix path (default: /usr/local/nginx/ ). (version >= 0.7.53)
-c filename	Specify which configuration file NGINX should use instead of the default.
-g directives	Set global directives. (version >= 0.7.4)

NGINX has only a few command-line parameters. Unlike many other software systems, the configuration is done entirely via the configuration file (imagine that).

Stopping or Restarting NGINX¶

There are two ways to control NGINX once it’s already running. The first is to call NGINX again with the -s command line parameter. For example, /usr/bin/nginx -s stop will stop the NGINX server. (other -s options are given in the previous section)

The second way to control NGINX is to send a signal to the NGINX master process… By default NGINX writes its master process id to /usr/local/nginx/logs/nginx.pid . You can change this by passing parameter with ./configure at compile-time or by using pid directive in the configuration file.

Here’s how to send the QUIT (Graceful Shutdown) signal to the NGINX master process:

kill -QUIT $( cat /usr/local/nginx/logs/nginx.pid ) 

The master process can handle the following signals:

Start the new worker processes with a new configuration

Gracefully shutdown the old worker processes

There’s no need to control the worker processes yourself. However, they support some signals, too:

TERM, INT	Quick shutdown
QUIT	Graceful shutdown
USR1	Reopen the log files

Loading a New Configuration Using Signals¶

NGINX supports a few signals that you can use to control it’s operation while it’s running.

The most common of these is 15, which just stops the running process:

USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 2213 0.0 0.0 6784 2036 ? Ss 03:01 0:00 nginx: master process /usr/sbin/nginx -c /etc/nginx/nginx.conf

The more interesting option however, is being able to change the NGINX configuration on the fly (notice that we test the configuration prior to reloading it):

2006/09/16 13:07:10 [info] 15686#0: the configuration file /etc/nginx/nginx.conf syntax is ok 2006/09/16 13:07:10 [info] 15686#0: the configuration file /etc/nginx/nginx.conf was tested successfully USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 2213 0.0 0.0 6784 2036 ? Ss 03:01 0:00 nginx: master process /usr/sbin/nginx -c /etc/nginx/nginx.conf

What happens is that when NGINX receives the HUP signal, it tries to parse the configuration file (the specified one, if present, otherwise the default), and if successful, tries to apply a new configuration (i.e. re-open the log files and listen sockets). If successful, NGINX runs new worker processes and signals graceful shutdown to old workers. Notified workers close listen sockets but continue to serve current clients. After serving all clients old workers shutdown. If NGINX couldn’t successfully apply the new configuration, it continues to work with an old configuration.

RequestForReviewCategory – (Request For Review: Just What Happens With The Worker Processes at a HUP? -Olle)

Upgrading To a New Binary On The Fly¶

If you need to replace NGINX binary with a new one (when upgrading to a new version or adding/removing server modules), you can do it without any service downtime — no incoming requests will be lost.

First, replace old binary with a new one, then send USR2 signal to the master process. It renames its .pid file to .oldbin (e.g. /usr/local/nginx/logs/nginx.pid.oldbin ), then executes a new binary, which in turn starts a new master process and the new worker processes:

: PID PPID USER %CPU VSZ WCHAN COMMAND 33126 1 root 0.0 1164 pause nginx: master process /usr/local/nginx/sbin/nginx 33134 33126 nobody 0.0 1368 kqread nginx: worker process (nginx) 33135 33126 nobody 0.0 1380 kqread nginx: worker process (nginx) 33136 33126 nobody 0.0 1368 kqread nginx: worker process (nginx) 36264 33126 root 0.0 1148 pause nginx: master process /usr/local/nginx/sbin/nginx 36265 36264 nobody 0.0 1364 kqread nginx: worker process (nginx) 36266 36264 nobody 0.0 1364 kqread nginx: worker process (nginx) 36267 36264 nobody 0.0 1364 kqread nginx: worker process (nginx) 

At this point, two instances of NGINX are running, handling the incoming requests together. To phase the old instance out, you have to send WINCH signal to the old master process, and its worker processes will start to gracefully shut down:

: PID PPID USER %CPU VSZ WCHAN COMMAND 33126 1 root 0.0 1164 pause nginx: master process /usr/local/nginx/sbin/nginx 33135 33126 nobody 0.0 1380 kqread nginx: worker process is shutting down (nginx) 36264 33126 root 0.0 1148 pause nginx: master process /usr/local/nginx/sbin/nginx 36265 36264 nobody 0.0 1364 kqread nginx: worker process (nginx) 36266 36264 nobody 0.0 1364 kqread nginx: worker process (nginx) 36267 36264 nobody 0.0 1364 kqread nginx: worker process (nginx) 

After some time, old worker processes all quit and only new worker processes are handling the incoming requests:

: PID PPID USER %CPU VSZ WCHAN COMMAND 33126 1 root 0.0 1164 pause nginx: master process /usr/local/nginx/sbin/nginx 36264 33126 root 0.0 1148 pause nginx: master process /usr/local/nginx/sbin/nginx 36265 36264 nobody 0.0 1364 kqread nginx: worker process (nginx) 36266 36264 nobody 0.0 1364 kqread nginx: worker process (nginx) 36267 36264 nobody 0.0 1364 kqread nginx: worker process (nginx) 

At this point you can still revert to the old server because it hasn’t closed its listen sockets yet, by following these steps:

• Send HUP signal to the old master process — it will start the worker processes without reloading a configuration file
• Send QUIT signal to the new master process to gracefully shut down its worker processes
• Send TERM signal to the new master process to force it quit
• If for some reason new worker processes do not quit, send KILL signal to them

After new master process quits, the old master process removes .oldbin suffix from its .pid file, and everything is exactly as before the upgrade attempt.

If an update is successful and you want to keep the new server, send QUIT signal to the old master process to leave only new server running:

: PID PPID USER %CPU VSZ WCHAN COMMAND : 36264 1 root 0.0 1148 pause nginx: master process /usr/local/nginx/sbin/nginx : 36265 36264 nobody 0.0 1364 kqread nginx: worker process (nginx) : 36266 36264 nobody 0.0 1364 kqread nginx: worker process (nginx) : 36267 36264 nobody 0.0 1364 kqread nginx: worker process (nginx) 

References¶

Источник

How to Start Nginx on Linux?

Nginx is one of the most popular high-performance web servers for the modern age. It is popular for hosting high-traffic and resource-intensive applications. Pronounced as “engine-x,” it is a lightweight and highly configurable web server or a reverse proxy for other web servers.

Although Nginx is very stable and easily manageable, as a system administrator, you will encounter instances where you need to start, stop, or restart Nginx; for example, you may want to apply configuration changes or troubleshoot errors on the server.

This tutorial will discuss how to start, stop and restart the Nginx server on Linux systems using Systemd.

Pre-requisites

Before we proceed with the tutorial, it is good to ensure you have the following:

• Ensure you have Nginx installed and configured properly
• Have access to the root user or a sudo account.

With the above requirements met, we can begin:

What is Systemd?

Systemd is an init and service manager for Linux systems. Major Linux distributions, including Debian, Arch, REHL, and Fedora, have adopted Systemd. Systemd allows system administrators to start, stop, reload and restart services in the system. It also provides features such as logging, which is very useful in troubleshooting measures.

If you want to learn more about systemd, please consider the official documentation: https://systemd.io/

How to Manage The Nginx Service

Managing the Nginx service is quite simple, mainly because of the ease of use that Systemd gives us.

How to Start Nginx

To start the Nginx service on a Linux machine, use the command:

Assuming no encountered errors, you should see no output, and Nginx should be up and running.

Suppose you are not a system that uses init.d instead of the system; in that case, to start Nginx, use the command:

How to Stop Nginx service

In this case, the reverse is true. To stop Nginx service with systemd, the command is as:

Using init.d? use the command:

Reloading Nginx service

Nginx service also supports the reload function. This loads new configurations and restarts the worker processes using the loaded configuration. Reload feature is useful if you do not want to perform a complete reboot of the service.

To reload Nginx with systemd, use the command:

Use the command below for init.d systems.

Restarting Nginx service

Unlike reload, restarting the Nginx service will fully stop and start the server. To restart Nginx, use the command:

The command for SysVinit is:

Conclusion

This tutorial showed you how to manage the Nginx service on Linux systems, including those using Systemd and Init.d.

About the author

John Otieno

My name is John and am a fellow geek like you. I am passionate about all things computers from Hardware, Operating systems to Programming. My dream is to share my knowledge with the world and help out fellow geeks. Follow my content by subscribing to LinuxHint mailing list

Источник