Difference between revisions of "BOSS-Linux/C2/Basic-Commands/English-timed"

|In this tutorial, we will study some basic commands.  

|I am using '''Linux Operating System'''

|If you are interested, it is available through another spoken tutorial, on the website [http://spoken-tutorial.org/ http://spoken-tutorial.org].

|In this tutorial, we will see what are commands and what is a command interpreter.

|Linux commands are seldom more than four character in length like ''' ls, who, ps''' etc.  

|The commands are in lower case and they are case sensitive. Let us see an example .  

|Select '''Accessories''' and then click on terminal from the available options  

|Now we can see a prompt ($) and a cursor blinking next to it. This is where we need to type in a command.   

|Type in the words '''who''' and press enter.  

|This is the job of the Command Interpreter, also called the shell.  

|We can define a shell as a program that acts as the interface between us and the Linux system,  

|On Linux, the standard shell that is always installed as '''bin/sh''' is called bash, the '''GNU Bourne-Again Shell''', from the '''GNU''' suite of tools.  

|The commands we would be covering in this tutorial are generic and can run on most of the Linux shells with slight variations.  

|Nevertheless, we would be using the bash as the shell for demonstration in this tutorial.

|It is because bash is the most popular shell and portable to almost all '''UNIX.'''

|Other shells include the '''Bourne shell''' which is the original ''' Unix shell, C Shell''' and '''Korn shell'''

|and type the command ''' echo space dollar''' in capital '''SHELL''' and press enter

|Normally the output is '''/bin/bash''' which gives us the bash shell.  

| Type at the command prompt, ''' type space ps''' and press enter.

|This shows that '''ps''' is actually a file stored in the '''/bin''' directory.  

|For now, if we want to see this list, just type the command '''echo space dollar PATH ''' in capital

|and press enter

|Most commands in Linux are of this nature. But there are some commands whose implementation is written within the shell and they do not exist as separate files.  

|The '''echo''' command, which we will see later, is in fact an '''internal command.'''  

|Go to the terminal and type at the command,

|'''type space echo''' and press enter.

|The output shows '''echo as a shell built-in.'''  

|So instead of giving a file name it shows that the '''echo''' command's implementation is internal to the shell. So it is called '''internal command.'''

|In the second case the first word is the actual name of the command while the other words are the '''arguments.'''

|They are generally preceded by a single or double minus sign, called short and long option, respectively.  

|Go to the terminal window and type the commands and see their outputs.  

|Type '''clear''' to clear the terminal window

|Then type '''ls''' and press enter

|Again, type '''clear''' and press enter

|Type '''ls space minus a''' and enter.

|Type '''clear''' to clear the terminal window

|Now type '''ls space minus minus all''' and press enter.

|Now type '''ls space minus d''' and press enter.

|At this point it is enough to understand how the command's behavior changes with change of options

|In Linux we have a larger number of commands,

|Commands can also be combined together as we will see later. So how do we keep so much in mind?  

|For instance, to know about say, the '''ls''' command, all you have to do is to go to the terminal  

|and type '''man''' command with '''ls''' as argument that is type '''man space ls''' and press enter

|'''man''' is the system’s manual pager. Each argument given to man is normally the name of a program, utility or function.

|The manual page associated with each of these arguments is then found and displayed.  

|A section, if provided, will direct man to look only in that section of the manual.

|Go to the terminal and type '''man space man''' and press enter.

|Here let me tell the most useful ones. Sometimes we know what we want to do but do not know the exact command. Then what can we do?  

|'''man''' provides the '''-k''' option which takes a keyword and return a list of commands and their brief purpose.  

|For example, create a directory, we may not know the exact command,

| so we can go to the command prompt and type '''man space minus k space directories''' and press enter.  

|Type at the command prompt '''apropos space directories''' and press enter to see the output.

|Some times we do not need too much details. We only need to know what a command does.  

|In that case we can use the '''whatis''' command or '''man -f.''' Both give one line description about the command.  

|Go to the terminal, type '''clear''' to clear the terminal window

|now type '''whatis space ls''' and press enter

|Go to the command prompt and type '''ls space - -(minus minus) help'''  and press enter

|I will scroll up so that you can see all the options on this manual page  

|Thats it for this part of the Linux Spoken tutorial. Spoken Tutorials are a part of the Talk to a Teacher project, supported by the National Mission on Education through ICT.  

|  Thanks for joining us. This is Anuradha Amrutkar signing off. Good Bye.