Salix Mini Walkthroughs

Working with the Command Line Interface

This section deals with working in a console mode or with a terminal (such as Xfce terminal, xterm, konsole and so forth), and serves merely as a light introduction to the command line interface (CLI). The intended audience here is not seasoned travelers but new journeymen in the land of Linux, who are willing to discover more about what one can do with it. We will go through some examples in this section for you to follow, and hopefully by the end of this walkthrough, you will have no problem working with the “black screen”. For those who would like to know more about CLI, there are a couple of useful resources available on the net, and some are listed in the Salix Forum.

So why learn CLI commands at all? Graphical user interfaces for applications have been steadily improving in Linux and are probably now comparable to any OS in their ease of use. On the other hand, where Linux excels, in particular, is in the area of command line applications, its traditional strength. Without the CLI, you would be effectively missing out on half of what Linux can offer.

There is another reason. From time to time, you might have to work in the console. For instance, if the machine fails to start up a graphical desktop environment during booting, then you are more or less forced to fix the problem without the graphical user interface (GUI).

Of course, there are many other reasons to learn CLI commands, but for now we will start by learning how to move around directories.

First, open up a terminal or move to a console: you can do the latter by pressing Ctrl+Alt+F2, for example. To get back to the graphical desktop, press Alt+F4, for example. F number keys are used to switch between consoles; if F4 or F7 doesn’t do the trick, try others.

However, the simplest option is to open a terminal within the GUI: there is probably an option to do so in the panel, or if not, in the menu.

Moving Around - cd

You should be in your user directory (denoted as ~), which is normally the same as /home/your_user_name (replace your_user_name with your own). In Salix, this directory contains Desktop, Music, Documents and so on. To see its contents, type ls and press enter. You will see something like this:

george[~]$ ls
Desktop      Download    Pictures    Templates    salix
Documents    Music       Music       Videos

Now to move around directories, we use the command cd. If you just type in cd and enter, it will take you to your home directory, but as we are already there, in this case, nothing will happen. cd must otherwise be followed either by a name of a directory which is within the directory you are in or by a full path to the directory you wish to move into. You can also go one directory up by typing

cd ..

(be careful, there is a space between cd and ..). Remember in Linux, arguments are separated by spaces. So for now, let’s move to the root directory. The root directory is, as the name suggests, the core of your directories - every directory stems from here.

To move to the root /, type in

cd /

Type in ls to see the list of files and directories in the directory. You should see something like tmp/, usr/, home and so on. OK, not so interesting here. Let us move back to your home directory with

cd /home/your_user_name

or just

cd

Now move into the Music directory by issuing

cd Music

In fact, you do not have to type to the end. By pressing Tab after the first letter or two, you may complete the rest of the directory name automatically.

The important thing to notice here is this is a relative path: unlike where the whole path was specified above, starting from the root of the filesystem /, if the path doesn’t begin with / it is understood as starting from whatever the current directory is, in this case, your user’s home. So Music, in this case, means the same as /home/your_user_name/Music.

Creating a Folder - mkdir

You can create a folder by issuing

mkdir name_of_a_new_folder

For example, let’s say we are going to create a photo folder.

mkdir photo

will place the new folder in the current directory. You can check this by typing

ls

Next, let’s create a log file for the photo folder. nano is a command-line application for reading and writing texts. To bring up the program, type in

nano

The application is simple to use, and you can see command options shown at the bottom. Type

log file created

and with Ctrl+x, save the document as log and quit the application.

Copying & Moving & Removing a File - cp & mv & rm

cp is perhaps one of the most used commands in a console mode. cp copies a file or files from one location to another. Since we created the file called log and it is currently in the wrong directory, let us move it inside the photo directory. You can do so by issuing cp log photo/ but perhaps it is better to call the log file not just log but log.txt, so that it would be obvious to a Windows user that it is a text file. Type in

cp log photo/log.txt

and enter to execute the command.

You can go inside the photo directory and check if the copying has been done properly. cd photo and then ls. The file should be there. Let’s add to the log file by saying that it has been moved from Music to photo. Issuing

nano log.txt

will bring up the text. Add a line to say it has been moved, and then save and quit the application by Ctrl+x.

Oh, but we forgot to delete the original log file in the Music folder. Let’s just get back to the Music directory using cd .. and remove the log file by issuing rm log. The rm command removes a file or files. For example, if you would like to remove all photos with .jpg extension but not with .png, you can issue a command something like:

rm *.jpg

This will remove all the files with .jpg extension within the directory you are in. Note that the rm command will not ask you to confirm your order. It will just carry out your instructions without further ado and once a file is removed, it is deleted forever. You cannot recover it from the recycle bin.

In this example, we used cp to copy the log file and then later on deleted it. Normally, this would be done by issuing a mv command;

mv log photo/

You can also use the mv command to rename a file. Let’s say that you did not like the earlier decision to call the log file log.txt and you now want to rename it as log again. Type in

mv photo/log.txt photo/log

and execute the command. Now the file name has been changed back to log.

Copying & Moving & Removing a Folder - cp & mv & rm

So now you have the folder called photo and a log file in the Music directory. This is a little strange as we should normally have the folder not in Music but in Pictures. But now you know how to move a file, perhaps the same command will work for moving a folder?

But…

cp photo ../Pictures

remember that .. refers to the folder one level up) will give an error like this.

george[Music]$ cp photo ../Pictures
cp: omitting directory 'photo/'
george[Music]$

Let’s see what we can do here. The first thing when encountering such a problem is to check the corresponding help file. This can normally be done by issuing a command with an option like cp --help. It is possible that --help will just be -h, and there may be no help at all. man is another command if this is the case.

man cp

will give a more in-depth explanation of this command. (To get out of the manual, press q).

If you read the help carefully, you will see that you need to give an extra option -r if you wish to copy a folder to another location. So now

cp -r photo ../Pictures

should copy the photo folder inside the correct Pictures directory. After checking that the folder has been safely copied, you can remove the photo folder from the Music directory:

rm -r photo/

Installing a Program - slapt-get

Maybe a little bird has told you that there is a wonderful application called cowsay in Linux, and now you would like to see what this program can do.

If this is the first time you are installing an application on Salix, the first thing you should do is to update the package database on your computer by executing

sudo slapt-get -u

Then to search for an application (in this case, “cowsay”), type in

slapt-get --search cowsay

Notice that you don’t need to type sudo just for searching for a package. The output you will get should be similar to this:

george[~]$ slapt-get --search cowsay
cowsay-3.03-noarch-1salix15.0 [inst=no]: cowsay (A Configurable Speaking/Thinking Cow)
xcowsay-1.5.1-x86_64-2salix15.0 [inst=no]: xcowsay (display a cute cow and speech bubble)

To install it, you simply must run:

sudo slapt-get -i cowsay

If you are not sure what this -i is in the above command, you can check it with slapt-get --help. You will see a lot of lines running up the terminal quickly until the application is installed.

Once it is installed, you might want to test it. First get out of the superuser mode by typing exit. Then type in cowsay. Nothing happens, and, in fact, you will see that you are now in a strange mode that you cannot execute any commands. This is because the application is still running, but as you don’t see anything, perhaps it is not running properly. To terminate the process, press Ctrl+c. You will get back the normal input line back on your terminal.

george[Desktop]$ cowsay
^C
george[Desktop]$

So what was going wrong? Check

cowsay -h

You will see that you need to type in a [message]. Try again with

cowsay Hello Salix!

We have merely scratched the surface of the power of the command line here. The best way to learn more is by using it, but remember to use the help tools, and consult online documentation such as that listed in the Salix forum. Linuxcommand.org can be particularly recommended if you wish to gain a comprehensive grounding. Proceed cautiously, but don’t be afraid to experiment.

A final tip - it can be difficult to copy longer commands accurately. If you select the text with the mouse, clicking the middle button or wheel will paste it accurately into the command line or wherever you wish. This only works in a terminal running within a GUI.