Remote Linux Server Tutorial

Warning

The use of SSH server is optional as long as you have a compatible local development environment (bash CLI environment) such as Windows WSL, Mac OS or Linux. It is only required if you want to use incompatible environment like MinGW or CygWin to develop C/C++ programs on Windows. You will need SSH server in this case. Take your own risk in this case and I am not capable of providing support for these environments.

There are several Linux servers available to CS students for teaching purposes. The servers can be accessed through secure shell (SSH). The host name for the servers is cs-ssh.uwf.edu.

VS Code Remote SSH

The easiest way to work with the remote server is to use the Remote - SSH extension in Visual Studio Code. You can install the extension from the extension marketplace. Once installed, you can connect to the remote server using the Remote - SSH: Connect to Host… command in the command palette (Ctrl+Shift+P). You will be asked to input the host name. Input the host name cs-ssh.uwf.edu and you will be asked to input your username and password. Once connected, you can open a terminal in VS Code and work with the remote server as if you are working on your local machine. You can also open folders on the remote server and edit files directly in VS Code.

SSH client

You will need an SSH client to connect to the remote server. The standard command-line environments mostly come with a ssh command that you can invoke to connect to servers providing ssh service. These environments include the terminal app available on Linux, Mac OS and Windows Subsystem for Linux (WSL).

To connect to an SSH server on Windows without a terminal, you will need a standalone SSH client software. The most popular SSH client on Windows is Putty. You can find it free online and install it.

SSH command

You need to know the basic SSH command usage to connect to a remote server in your terminal. Use the following command and replace ``uname`` with your uwf email ID (part before @ in your UWF email address):

ssh uname@cs-ssh.uwf.edu

You will be asked if the server looked safe in your first attempt to connect. Just type yes. Then, input your password to log into the Linux.

You may add your public key to the server to avoid future hustle to input passwords. Read the ssh key-pair instructions on how to set up a key pair to use with SSH for instant login.

Warning

When you are asked to input the password, no change like moving cursor or stars will appear in the terminal. You will need to type blindly!

Typical SSH Errors

  • Time out

    It is usually a network problem. You should check your internet connection. It may also be an IP ban caused by multiple failed password input. This can be solved by submitting a ticket to the help desk.

  • Wrong password

    People tend to expect a cursor move when inputting the password. In terminal, you will always need to type passwords blindly. Or type in an editor and paste to the terminal window.

Work with Linux

Once you are logged in. You will be manipulating the remote Linux the same way as you can do with your local Linux in its terminal. You need some knowledge of basic Linux commands to do your work on the server. The common Linux commands can be found here.

ls

List all objects in a directory. Add the -l option to list in a long format. Add the -a option to list all including hidden objects. This command can be followed by a list of objects to be listed. Listing a directory will show objects in the directory. Listing a file object will list a single file.

cd

Change the working directory to a new location. You can use cd .. to change to the parent directory. .. represents the parent directory in Linux. Learn Linux directory structure for more information. A typical Linux path looked like /usr/lib/lab.so in which the slash symbol is the delimiter.

mkdir

Followed by a directory name to make a directory or a list of names to make several directories.

rm

Remove objects. Can remove files or directories. Add -r to remove a directory recursively.

man

Show the manual of a command. E.g. man ls to show the manual for the ls command.

./main

Run a program called main in the current directory. Must prefix with ./ before the name in which . represent the current directory in Bash. You can change main to the name of any program in the current directory to run it.

Refer to this Linux cheat sheet for more information.

Edit in the SSH window

Use vim editor

To edit a remote file directly in the terminal or SSH client window. You must use a command-line editor like vi, vim, nano, etc. vim is an enhanced vi editor and is widely used as a command-line text based editor. vim is extremely powerful, but at the same time hard to learn and master. Many programmers found it worth the time to learn it, including myself. You can learn several basic operations in vim to get it started to edit your code.

When you type the command vim main.cpp to edit a file called main.cpp in the current director, you will enter the full screen edit mode and your main.cpp file will be opened. You can press i key (case sensitive) to enter the insert mode and type your content. Press Esc to exit the insert mode and type :wq to save and quit.

To learn more about vim, check out the introduction to VI and VI cheatsheet documents.

The nano command can invoke a simpler text editor. You can learn how to use nano if you prefer a simpler editor.

Note

You always have the option to edit your code on your own computer and transfer to the server. So you do not have to edit in the terminal window.

File Transfer

As mentioned above, you can transfer locally-edited files to the server instead of creating and editing in the terminal window. There are many tools supporting file transferring through an SSH connection (SFTP):

  • Command line tools: scp, rsync

  • GUI tools: WinSCP (Windows only), FileZilla (All platforms)

Warning

If you are transferring a file generated on Windows using certain editors, you may experience line ending problem. The transferred file cannot be compiled because of the Windows line ending. You have to use a tool called dos2unix to convert the line ending characters. Unfortunately, this tool is not pre-installed on many Linux servers. One solution is to use an editor on Windows that can save files using the Unix line ending. It is know to work in VS code and you can perform a web search to see if your favorite editor will provide the option.