Once I installed a development service on port 3000 and I forgot about it. When I ran my project I couldn't start it because the port was in use. Baffled.
This post forms part of a sequence of command line references that I will be writing where I forget the command or its syntax.
Although it is easily Google-able, there are usually a chain of commands that I want kept together for ease of use.
The commands I use should be universal but just in case, I am running Fedora release 28 (Twenty Eight).
Also, if you want to contribute something interesting in any of my posts, please create a pull-request or write a comment below.
Getting back to my forgetfulness. I wanted to know what was using that port. I'll get to that. First let's take a look at how I interrogate the system to get a list of running services.
systemctl let's us query or send control commands to the
systemd starts core programs, journal of system activity,
the network stack, a cron-style job scheduler, user logins and other
jobs. Find out more at ZDNet.
If we want to find a list of installed programs and services (units) that are enabled:
systemctl list-unit-files | grep enabled
If we want to print out all services and see if they have been loaded or not:
systemctl -l --type service --all
To get to the meat of the problem I interrogate the network, get a pid and kill it. I can also uninstall the service if I no longer want it to run.
netstat prints network connections, routing tables, interface statistics, masquerade connections, and multicast memberships.
When I run the below command, I can see the program name and pid
sudo netstat -tulpn | grep 3000
Another command can be run using
ss which is a utility to
sudo ss -lptn 'sport = :3000'
sudo systemctl stop [servicename] sudo systemctl disable [servicename]
Once I have a pid for the process I want to shut down, I can kill it.
First I query the process to make doubly sure
ps -aux | grep 12345
Then I can kill it
sudo kill 12345. In some cases, the kill
doesn't want to play along in which case I need to force it,
sudo kill -9 12345.
If I am adamant that the service should not exist, I can uninstall it.
sudo systemctl stop [servicename] sudo systemctl disable [servicename] sudo rm /etc/systemd/system/[servicename] sudo rm /etc/systemd/system/[servicename] #symlinks that might be related sudo systemctl daemon-reload sudo systemctl reset-failed
systemctl list-unit-files | grep enabled systemctl -l --type service --all
sudo netstat -tulpn | grep 3000 sudo ss -lptn 'sport = :3000'
ps -aux | grep 12345 sudo kill 12345 sudo kill -9 12345
systemctl stop [servicename] systemctl disable [servicename] rm /etc/systemd/system/[servicename] rm /etc/systemd/system/[servicename] systemctl daemon-reload systemctl reset-failed