Command Line & The Shell

Describes the basic steps of how to use the command line.

Overview

POCS is designed to be run without a monitor connected to it, which may be unfamiliar to most people. The way we control and give commands to POCS is via the “command line,” which are commands that are typed into what is known as a “shell.”

You can think of the shell like the search bar on your internet browser. When you type in something you want to find, it’s like typing “search for pictures of the Orion Nebula.” In this case the “search for” would be the command you are running and “pictures of the Orion Nebula” are the parameters you give to the command.

Our command line is the same, it’s just that there are a lot more choices and instead of using the search bar, we enter commands in the shell “prompt.”

An example of a command line prompt in the shell. Here we have turned off the fans in one command and after returning the result, we are given another prompt to type more commands. The green square is where typed characters wil appear.

We try to minimize the number of commands you need to know by giving a single command, pocs, that has a lot of different sub-commands and options.

For instance, after Installing POCS, you can turn off the power to the fans, by typing pocs power off fans, where “pocs power off” is the command and sub-commands and “fans” is the parameter.

Getting a shell

If you used SSH Accessto connect to the computer, then you will already be using a shell. If you have a desktop environment connected you can search the Applications menu for a “Terminal” or “Console”, both of which are graphical programs that provide shell access.

Sudo

Some commands require the “root” or “super user” to perform because they can alter the state of the computer. To enter these commands you type sudo command and then will be asked for your password before the command is run. An example of this would be rebooting the computer, which can be done with sudo reboot.