systemd and FTP

For the last piece of this unit about an introduction to web services, we will talk about the program that manages all services (systemd) and the file transfer protocol (FTP).

systemd

If you are familiar with Windows, you may have seen the “Task Manager” service. That service manages all processes on the computer including background ones. On most Linux devices, systemd is the equivalent, but it only focuses on background processes. The d in systemd stands for “daemon” (pronounced “demon”) which means it runs in the background.

To control these services, we have been using systemctl e.g.

sudo systemctl status nginx

To see everything that systemd is managing, you can list the services.

sudo systemctl -l

ssh config

When you have many servers that you are connecting to over ssh, you can define a list of them in a config file so that you don’t have to remember a bunch of IP addresses.

# make the .ssh directory if it doesn't exist yet
mkdir -p ~/.ssh
vi ~/.ssh/config 

Host  yourhostname # anything you want
  User yourusername 
  Hostname 0.0.0.0 # insert correct ip
  Port 2112 # 22 by default but Mr. Buckley's server uses this.

Then you can connect using the Host.

ssh yourhostname

ftp

ftp or “file transfer protocol” is a way to connect to a remote computer and transfer files easily. It runs on port 20 or 21. The secure version, sftp connects over ssh on port 22 by default.

# if configed in ssh conf
sftp hostname
# or
sftp username@hostname:port

Note that ftp uses absolute paths and behaves kind of like a minimal shell.`

sftp> ls
sftp> cd directory
sftp> put /path/to/file.txt         # from you to the server
sftp> get /path/to/remote/file.txt  # from the server to you