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Linux commands for beginners

Three commands cover the start. One says the folder, another lists the names, the third goes somewhere else.

| Linux • Linux basics

Comandu penguin with a laptop and the commands ls, cd, sudo, and apt

The terminal is a conversation

You write a command, press Enter, and the terminal answers. It is not a menu. The answer is what matters: a path, a list of names, or the silence of an empty folder.

At the start, three commands cover almost everything you need to find your way. Each one answers a single question. If the question is wrong, the right command looks useless.

The line below already shows the place

Before you type, look at the prompt. It is the line that ends in $. The text before it says who you are and which folder the terminal is in right now.

bash - comandu
aluno@desafio:~$

aluno is the user. desafio is the machine name. ~ is a shortcut for your home folder. $ is the invitation: you can write the command.

The command goes before Enter. A space separates the command from what comes after it. Capital letters count. pwd exists. PWD does not.

Solve

You wrote PWD and the terminal answered command not found. What happened?

pwd says the folder in full

pwd prints the full path of the current folder. It does not list files. It does not change place. It only answers: where am I.

Solve

You just opened the terminal and want to know which folder you are in. Which command?

bash - comandu
aluno@desafio:~$ pwd
/home/aluno

The line that starts with / is the answer. /home/aluno means: inside home, this user's folder. The tilde on the prompt is only a shortcut for that same place. The two texts talk about the same folder.

ls lists the names

ls shows what is inside the current folder. Each name is a file or another folder. The command does not go anywhere.

bash - comandu
aluno@desafio:~$ ls
Documents  Downloads  reports

If the folder is empty, ls writes no line and the prompt comes back. That is not an error. There was no name to show.

Figure it out

ls went straight back to the prompt, with no text. What does that mean?

cd changes folder

cd switches the current folder. The name after it has to exist. After the command, the prompt changes. pwd confirms the new path.

bash - comandu
aluno@desafio:~$ cd reports
aluno@desafio:~/reports$ pwd
/home/aluno/reports

Notice the difference. ls reports would show what is inside without leaving the folder above. The next command would still be in /home/aluno. cd reports is what changes the place.

Solve

ls showed the reports folder. You want the next command to run inside it. What comes now?

The order that does not confuse

First confirm the folder with pwd. Then look at what is there with ls. Only then go somewhere else with cd. At the end, run pwd again. If the path changed, cd worked.

bash - comandu
aluno@desafio:~$ pwd
/home/aluno
aluno@desafio:~$ ls
Documents  Downloads  reports
aluno@desafio:~$ cd reports
aluno@desafio:~/reports$ pwd
/home/aluno/reports

Figure it out

You ran cd /tmp. Which command confirms that the folder changed?

The next step is navigating folders: see the place, list, enter, and go back. When a command says it cannot run, the subject is already permissions.

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Linux basics