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Getting to know the terminal

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Overview

This tutorial will walk you through some more advanced commands that you can perform in a UNIX-like terminal, which the SRCF provides you with. You will learn many of the basic commands that are used and why in conjunction with other tools they can be very powerful.

This tutorial assumes you have an SRCF personal account (with or without group account admin permissions) and can SSH. See our other tutorials for that.

Introduction

The SRCF offers you much more than just a web server - everyone who has an account has full shell access to our Linux servers. This allows you to manipulate and edit the contents of your filespace directly without having to worry about downloading and uploading files, as well as running all sorts of other software which you might not have available to you under your usual operating system.

Basic commands

After sucessfully loging in you will see a few lines of text welcoming you to the system and telling you any recent news, followed by a command prompt:

    pip:~$

You are now logged in and can give the system commands by typing them after the prompt. If you wish to start a particular program, the command is just the name of the program you wish to run. For example typing ‘date’ and pressing return will tell you the current date and time:

    pip:~$ date
    Wed Apr  5 22:29:11 BST 2020
    pip:~$

After each command has finished, a new prompt will be displayed ready for the next command. Some interactive programmes, such as the email reader pine will fill the whole screen, but will still return to the command prompt afterwards.

Commands with arguments

Some commands require arguments, that is additional parameters which alter the way that they run, for example the command ‘ping’, which is used to check the speed of an Internet connection, requires the name of a host as an argument:

    pip:~$ ping www.bbc.co.uk
    PING www.bbc.net.uk (212.58.224.35): 56 data bytes
    64 bytes from 212.58.224.35: icmp_seq=0 ttl=247 time=4.9 ms
    64 bytes from 212.58.224.35: icmp_seq=1 ttl=247 time=4.6 ms

    --- www.bbc.net.uk ping statistics ---
    2 packets transmitted, 2 packets received, 0% packet loss
    round-trip min/avg/max = 4.6/4.7/4.9 ms
    pip:~$

(To stop the ‘ping’ program, press control-c)

To find information about the arguments for a command, use the ‘man’ command, for example ‘man ping’ will tell you about the ‘ping’ command. Use the arrow keys to scroll through the man text and press ‘q’ when you want to return to the command prompt.

File system

All files stored on the system reside in directories (this is the equivalent of Windows folders). The directories are arranged in a hierachical structure - directories may contain subdirectories and so on. The top of the hierarchy is called the root directory, and is represented by /. Other directories are refered to by their path, for example, /home/abc45/ represents the directory abc45 which is a subdirectory of ‘home’, which in turn is a subdirectory of the root directory.

Files can be specified by adding the file name to the end of the path, for example /home/abc45/my_file.txt is a reference to the file my_file.txt which is stored in the directory /home/abc45/.

At any point during your session you will be ‘in’ a particular directory called the working directory. Rather than using full paths as above, it is possible to refer to the location of files relative to working directory by omitting the leading /, for example ‘my_dir/my_file.txt’ represents the file ‘my_file.txt’ within the directory ‘my_dir’, which is a subdirectory of the working directory.

Filenames given without a preceding path are assumed to be in the working directory. All directories have a special subdirectory called .. which refers to the directory one level higher up in the hierachy (the parent direcvtory), so ../some_file.txt is the file some_file.txt in the parent directory of the working directory.

To find out your current directory, use the command pwd:

    pip:~$ pwd
    /users/abc45
    pip:~$

You can change the working directory by using the cd command, for example:

    pip:~$ cd my_dir
    pip:~/my_dir$

Notice how the working directory is displayed as part of the command prompt. The symbol ~ is an abbreviation for your home directory, in other words the directory you start off in when you first log in.

To view the contents of the working directory, use the command ‘ls’:

    pip:~$ ls
    public_html  mygroup  my_file.txt
    pip:~$

Alternatively, use ls -alF to give more detailed information. The above example shows that the working directory has two directories public_html and mygroup, the first of which contains your web space and the latter of which is a link to the mygroup group account file space.

There is also one file, ‘my_file.txt’ (there is no way of differentiating between files and directories in the above example - you need to use the ls -alF form to show that information).

More commands

The following table gives some common commands used to manipulate files:

+-----------------------------------+-----------------------------------+
| Command                           | Meaning                           |
+-----------------------------------+-----------------------------------+
|     cp <file1> <file2>            | Creates a copy of 'file1' at      |
|                                   | the location specified by         |
|                                   | 'file2'                           |
+-----------------------------------+-----------------------------------+
|     mv <file1> <file2>            | Moves 'file1' to the location     |
|                                   | specified by 'file2'. Note that   |
|                                   | if 'file1' and 'file2' are in     |
|                                   | the same directory you can use    |
|                                   | this command to rename the file.  |
+-----------------------------------+-----------------------------------+
|     rm <file>                     | Deletes 'file'                    |
+-----------------------------------+-----------------------------------+
|     mkdir <dir>                   | Creates a directory called        |
|                                   | 'dir'                             |
+-----------------------------------+-----------------------------------+
|     rmdir <dir>                   | Removes the directory 'dir' (it   |
|                                   | must be empty first)              |
+-----------------------------------+-----------------------------------+
|     nano <file>                   | Edits 'file' using the 'nano'     |
|                                   | text editor.                      |
+-----------------------------------+-----------------------------------+

Note that the last command starts the nano text editor. This is a very powerful editor which is worth getting to know, but it can seem complex at first. If you get stuck in it, pressing control-x will return to the command prompt.

Exiting

To log out of the system, type ‘exit’ at the command prompt.

Closing remarks

Did you like this or find this cool? We invite you to check out more tutorials or get in touch to tell us what you thought!

If you have any suggestions for how we could improve this documentation please send us an email at support@srcf.net or submit a Pull Request on GitHub!

Last modified on Thursday Apr 22, 2021 by Matias Silva