Check running services on Linux
When you need to troubleshoot a network service, the first step is to ensure that the service is running.
If the service has an init script installed, you can use the
service command to start, stop,
and check the status of the service. The service command references a service by using
its init script, which is stored in the /etc/init.d directory for debain based distributions and the
etc/rc.d/init.d directory for Red Hat based distributions.
If you aren’t sure what name the system uses for a service, check either directory by
ls command followed by the directory. Some names vary depending on your
distribution. For example, Apache is
httpd on CentOS and
apache2 on Ubuntu.
Note: Many newer Linux distributions use systemd instead of netstat for checking services. If you are using systemd, replace all
service <service-name> <status> commands with
systemct1 <status> <service-name>. For more information about
systemct1 commands, see the Fedora SysVinit to Systemmd Cheatsheet.
Check the service status
A service can have any of the following statuses:
start: The service has started.
stop: The service has stopped running
restart: The service is rebooting and will start after the process is complete
The following example shows how to check the status of
httpd on CentOS
$ sudo service httpd status httpd is stopped
Start the service
If a service isn’t running, you can use the
service command to start it.
$ sudo service httpd start Starting httpd: [ OK ]
If the application can’t be started, the system reports the failure and usually shows a message explaining the reason.
$ sudo service httpd start Starting httpd: (98)Address already in use: make_sock: could not bind to address [::]:80 (98)Address already in use: make_sock: could not bind to address 0.0.0.0:80 no listening sockets available, shutting down Unable to open logs [FAILED]
Use netstat to find port conflicts
In the preceding example,
httpd can’t be started because something is
already listening on the port. To find out what it is, you can run
Run the following command to display a list of listening programs and the ports that they are using.
# netstat -plnt Active Internet connections (only servers) Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name tcp 0 0 10.176.77.113:3306 0.0.0.0:* LISTEN 28509/mysqld tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN 2113/nc tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN 1115/master tcp 0 0 :::22 :::* LISTEN 1051/sshd
The output shows that the nc program (listed in the
Program name column) is listening on
port 80 (in the
Local Address column). Stopping it should allow
httpd to be started.
Note: For more information about
netstat command, see Check listening ports with netstat
Check xinetd status
If the service isn’t running, it might be because a super-server, such as xinetd, is being used to launch the program when a connection is received. Starting the service might have resolved the issue. Run the following command to verify:
$ sudo service xinetd status xinetd (pid 8795) is running...
If you can’t start your service, look at your logs to see if they contain information about the issue.
Once you’re sure the application is running, check the server resources that your application is consuming.
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