How To Know Services Running In Unix

A Linux systems provide a variety of arrangement services (such every bit process management, login, syslog, cron, etc.) and network services (such as remote login, e-post, printers, web hosting, data storage, file transfer, domain proper noun resolution (using DNS), dynamic IP address assignment (using DHCP), and much more).

Technically, a service is a procedure or group of processes (ordinarily known as daemons) running continuously in the background, waiting for requests to come in (peculiarly from clients).

Linux supports different ways to manage (start, stop, restart, enable auto-start at system boot, etc.) services, typically through a process or service manager. Most if non all modern Linux distributions at present employ the aforementioned process manager: systemd.

Read Too: The Story Behind 'init' and 'systemd': Why 'init' Needed to be Replaced with 'systemd' in Linux

Systemd is a arrangement and service manager for Linux; a drop-in replacement for the init process, which is compatible with SysV and LSB init scripts and the systemctl command is the primary tool to manage systemd.

In this guide, nosotros will demonstrate how to list all running services under systemd in Linux.

List Running Services Nether SystemD in Linux

When you run the systemctl command without whatever arguments, it will brandish a list of all loaded systemd units (read the systemd documentation for more data about systemd units) including services, showing their condition (whether active or not).

# systemctl

To list all loaded services on your organization (whether active; running, exited or failed, use the list-units subcommand and --type switch with a value of service.

# systemctl list-units --type=service OR # systemctl --type=service

List All Services Under Systemd — Listing All Services Under Systemd

And to listing all loaded but active services, both running and those that have exited, you tin can add the --country pick with a value of active, as follows.

# systemctl list-units --type=service --state=active OR # systemctl --type=service --state=active

List All Active Running Services in Systemd — Listing All Active Running Services in Systemd

Merely to get a quick glance of all running services (i.e all loaded and actively running services), run the following command.

# systemctl listing-units --type=service --state=running  OR # systemctl --blazon=service --land=running

If y'all frequently utilize the previous command, you tin create an allonym command in your ~/.bashrc file equally shown, to hands invoke it.

# vim ~/.bashrc

So add the following line under the listing of aliases every bit shown in the screenshot.

alias running_services='systemctl list-units  --type=service  --state=running'

Create a Alias for Long Command — Create a Alias for Long Control

Save the changes in the file and close it. And from now onwards, use the "running_services" command to view a list of all loaded, actively running services on your server.

# running_services	#use the Tab completion

Also, an important aspect of services is the port they employ. To determine the port a daemon process is listening on, y'all can use the netstat or ss tools as shown.

Where the flag -50 means print all listening sockets, -t displays all TCP connections, -u shows all UDP connections, -due north means print numeric port numbers (instead of application names) and -p ways evidence application proper noun.

# netstat -ltup | grep zabbix_agentd OR # ss -ltup | grep zabbix_agentd

The fifth column shows the socket: Local Address:Port. In this example, the process zabbix_agentd is listening on port 10050.

Besides, if your server has a firewall service running, which controls how to block or allow traffic to or from selected services or ports, you can list services or ports that take been opened in the firewall, using the firewall-cmd or ufw command (depending on the Linux distributions you are using) as shown.

# firewall-cmd --list-services   [FirewallD] # firewall-cmd --list-ports  $ sudo ufw condition     [UFW Firewall]

List Open Services and Ports on Firewall

That's all for now! In this guide, we demonstrated how to view running services under systemd in Linux. We also covered how to check the port a service is listening on and how to view services or ports opened in the organization firewall. Do you have any additions to make or questions? If yes, accomplish us using the comment form below.

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