2023-03-11

Basic navigation in terminal

Most of us rarely use the terminal application to interact with our computers, but in coding it's very useful to be able to do this. Using the terminal application on your machine is sometimes called using the command line, and many programs we use come with both a graphical user interface (gui) and a command line interface (cli).

Open a terminal window

This means go to your computer's terminal application. On a windows machine, we are talking about the regular terminal application, not PowerShell. This is important, because windows PowerShell has its own syntax and it operates on weirdly different assumptions than a regular terminal application does. Windows 10 and later does have a windows terminal application, although in older versions it was called the command prompt or cmd window. We don't use that one either.

On windows, we use the Debian terminal. Debian is a Linux system, so using the terminal means you'll be using Linux commands. On a Mac, the terminal application is just called terminal, and it uses Linux commands.

So to open a terminal, you can go to your apps or toolbar, find the correc application (wsl Debian or terminal), and open it up.

Working at the command line

When you open a terminal, you'll see a little string of characters on the left that typically include your username. For example, I see this:

amy@SBS-7719 ~ %

My username is amy, and I'm on a machine called SBS-7719. The tilde tells me I'm at my home directory, and the % says that I'm at the beginning of a command line.

You can type whomai and the system will return your username, then give you a new command prompt, like this:

amy@SBS-7719 ~ % whoami
amy
amy@SBS-7719 ~ %

You can type pwd for "print working directory" and find out where you are in the local file system, then return you to the command prompt, like this:

amy@SBS-7719 ~ % pwd
/Users/amy
amy@SBS-7719 ~ %

To see what files and directories are local to you, type ls or ls -la.
The ls command just lists file and directory names, and does not include hidden files. The ls -la command gives you the filenames, permissions, sizes, etc for all files, including hidden ones.

amy@SBS-7719 ~ % ls
Desktop
Downloads
[ etc ]
src
amy@SBS-7719 ~ %

To move into a directory on the list, use cd ./[directoryname], like this:

amy@SBS-7719 ~ % cd ./src
amy@SBS-7719 src %
amy@SBS-7719 ~ %

Now that we're in the src directory, we can use ls -la and not see a billion files.

amy@SBS-7719 src % ls -la
total 16
drwxr-xr-x 7 amy staff 224 Feb 19 14:04 .
drwxr-xr-x 20 amy staff 640 Mar 11 13:47 ..
-rw-r--r--@ 1 amy staff 6148 Mar 11 14:02 .DS_Store
drwxr-xr-x 8 amy staff 256 Feb 19 14:39 components
drwxr-xr-x 12 amy staff 384 Mar 11 13:04 images
drwxr-xr-x 9 amy staff 288 Feb 24 13:34 pages
drwxr-xr-x 3 amy staff 96 Feb 18 17:38 templates

in the above, we get list of file permissions, the number of files in each directory, the user who owns the directory, the group of that user, the size of the directory, an edited on date and the name of the directory. Any directory name that begins with . is a hidden directory that you would not see if you used ls instead of ls -la.

Here are more handy commands:

• To move up one level, use cd ... To move up two levels, cd ..\.., and so forth.
• To make a new directory, use mkdir [directoryname]
• To make a new textfile, use touch [filename]
• To open your VS code editor from wherever you are, use code .
• To open a file with nano, use nano [filename]
• To delete a file, use rm [filename]
• To delete a directory and everything in it use rm -rf [directoryname]
• To copy a file from another location to where you are, use cp [filepath\sourcefile] .
• To copy a file from where you are to another location, use cp [filename] [filepath\filename]

Working remotely in an ssh session

Connecting to a remote machine via ssh

To connect to a remote server, use ssh [username]@[serverURL]. For example, when I log into our ms azure vm, I type ssh avf@0.171.0.206. When you get there, you'll either have to authenticate with a pwd or an ssh key. After successfully authenticating, you'll get a command prompt and you'll be able to use all the commands listed here (except code .)

Note that in order to run docker on a machine you must have sudo ("superuser do") access to that machine. If you attempt to run a command on a remote machine and it doesn't work, try again with sudo and a space before the command.

Using your VSCode as a texteditor on a remote machine

In your local VSCode, find and install the 'Remote ssh` extension.

Open VS Code locally, and select View --> Command Pallette --> Remote SSH:connect to host.

You'll be prompted to log in to the remote machine using the ssh command above.
Once you're authenticated, you can open a directory on the remote machine using the File --> Open Folder command.

Pulling up a browser with the dev environment on a remote machine

Use the remote machine's URL instead of localhost. For example, point a browser to 0.171.0.206:3000 if you're developing on the ms azure vm at that URL.

Leaving your SSH session

When you're done working in a remote ssh session, end any processes that were running on the machine you logged into. Bring down the dev environment for example, by typing

sudo docker compose down

Once everything's safely shut down, type exit to leave the session.