Difference between revisions of "BOSS-Linux/C2/Basic-Commands/English-timed"
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|00:00 | |00:00 | ||
− | |Dear friends, welcome to a spoken tutorial on the Linux Operating System. | + | |Dear friends, welcome to a spoken tutorial on the '''Linux Operating System. ''' |
|- | |- | ||
|00:05 | |00:05 | ||
− | |In this tutorial, we will study some basic commands. | + | |In this tutorial, we will study some basic '''commands'''. |
|- | |- | ||
|00:10 | |00:10 | ||
− | |I am using | + | |I am using '''Linux Operating System'''. |
|- | |- | ||
|00:12 | |00:12 | ||
Line 16: | Line 16: | ||
|- | |- | ||
|00:17 | |00:17 | ||
− | |If you are interested, it is available through another spoken tutorial, on the website [http://spoken-tutorial.org/ | + | |If you are interested, it is available through another spoken tutorial, on the website [http://spoken-tutorial.org/]. |
|- | |- | ||
|00:26 | |00:26 | ||
− | |In this tutorial, we will see what are commands and what is a command interpreter. | + | |In this tutorial, we will see what are '''commands''' and what is a '''command interpreter'''. |
|- | |- | ||
|00:33 | |00:33 | ||
− | |Then we will learn about how to find help in Linux using the man command. | + | |Then we will learn about how to find help in Linux using the '''man''' command. |
|- | |- | ||
|00:39 | |00:39 | ||
Line 30: | Line 30: | ||
|In simplest terms we can say that Linux commands are words that when keyed in cause some actions to take place. | |In simplest terms we can say that Linux commands are words that when keyed in cause some actions to take place. | ||
|- | |- | ||
− | |00: | + | |00:51 |
− | |Linux commands are seldom more than four character in length like ls, who, ps etc. | + | |Linux commands are seldom more than four character in length, like ''' ls, who, ps''' etc. |
|- | |- | ||
|00:59 | |00:59 | ||
− | |The commands are in lower case and they are case sensitive. Let us see an example . | + | |The commands are in lower case and they are '''case sensitive'''. Let us see an example . |
|- | |- | ||
|01:05 | |01:05 | ||
− | |Go to the | + | |Go to the '''Applications''' menu. |
|- | |- | ||
|01:08 | |01:08 | ||
− | |Select | + | |Select '''Accessories''' and then click on '''Terminal''' from the available options. |
|- | |- | ||
|01:14 | |01:14 | ||
− | | | + | |Now we can see a '''prompt''' ($) and a cursor blinking next to it. This is where we need to type in a command. |
|- | |- | ||
− | |01: | + | |01:22 |
− | | | + | |Type the word '''who''' and press '''Enter'''. |
|- | |- | ||
− | |01: | + | |01:28 |
− | | | + | |We can see the name of the users logged in. Actually we have just executed a command called '''who''' which shows who are logged into the system. |
|- | |- | ||
− | |01: | + | |01:41 |
− | | | + | |But which entity is converting these commands which are nothing more than a few letters into actions? |
|- | |- | ||
|01:47 | |01:47 | ||
− | | | + | |This is the job of the '''Command Interpreter''', also called the '''shell'''. |
|- | |- | ||
− | |01: | + | |01:53 |
− | | | + | |We can define a '''shell''' as a program that acts as the interface between us and the Linux system, |
|- | |- | ||
− | + | |02:02 | |
− | + | ||
− | + | ||
− | |02: | + | |
|allowing us to enter commands for the operating system to execute. | |allowing us to enter commands for the operating system to execute. | ||
|- | |- | ||
− | |02: | + | |02:07 |
|On Linux it’s quite feasible to have multiple shells installed, with different users able to pick the one they prefer. | |On Linux it’s quite feasible to have multiple shells installed, with different users able to pick the one they prefer. | ||
|- | |- | ||
− | |02: | + | |02:16 |
− | |On Linux, the standard shell that is always installed as | + | |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. |
+ | |- | ||
+ | |02:29 | ||
+ | |The commands we would be covering in this tutorial are generic and can run on most of the '''Linux shells''' with slight variations. | ||
|- | |- | ||
− | |02: | + | |02:38 |
− | | | + | |Nevertheless, we would be using the '''bash''' as the '''shell''' for demonstration in this tutorial. |
|- | |- | ||
|02:44 | |02:44 | ||
− | | | + | |It is because '''bash''' is the most popular shell and portable to almost all '''UNIX.''' |
|- | |- | ||
− | |02: | + | |02:52 |
− | | | + | |Other shells include the '''Bourne shell''' which is the original ''' Unix shell, C Shell''' and the '''Korn shell'''. |
|- | |- | ||
− | |02 | + | |03:02 |
− | | | + | |To see which shell we are using, go to the terminal |
|- | |- | ||
|03:08 | |03:08 | ||
− | | | + | |and type the command: ''' echo space dollar''' in capital '''SHELL''' and press '''Enter'''. |
|- | |- | ||
− | |03: | + | |03:21 |
− | | | + | |Normally, the output is '''/bin/bash''' which gives us the '''bash shell'''. |
|- | |- | ||
− | |03: | + | |03:28 |
− | + | ||
− | + | ||
− | + | ||
|There are ways by which we can activate different shells. Those will be covered in an advanced tutorial. | |There are ways by which we can activate different shells. Those will be covered in an advanced tutorial. | ||
|- | |- | ||
− | |03: | + | |03:36 |
|Commands are actually files containing programs, often written in C. | |Commands are actually files containing programs, often written in C. | ||
|- | |- | ||
− | |03: | + | |03:41 |
− | |These files are contained in directories. To find out where a command is stored, we can use the type command. | + | |These files are contained in directories. To find out where a command is stored, we can use the '''type''' command. |
|- | |- | ||
− | |03: | + | |03:48 |
− | | Type at the command prompt | + | | Type at the command prompt: ''' type space ps''' and press '''Enter'''. |
|- | |- | ||
− | | | + | |03:58 |
− | |This shows that ps is actually a file stored in the /bin directory. | + | |This shows that '''ps''' is actually a file, stored in the '''/bin''' directory. |
|- | |- | ||
− | |04: | + | |04:03 |
|When we key in a command at the command prompt, the shell searches for a file matching the command name in a list of directories. | |When we key in a command at the command prompt, the shell searches for a file matching the command name in a list of directories. | ||
|- | |- | ||
− | |04: | + | |04:12 |
|If it is found, then the program corresponding to that file is executed, else a “command not found” error is given. | |If it is found, then the program corresponding to that file is executed, else a “command not found” error is given. | ||
|- | |- | ||
− | |04: | + | |04:21 |
− | |The list of directories searched is specified by the PATH variable, as we will see later. | + | |The list of directories searched is specified by the '''PATH''' variable, as we will see later. |
|- | |- | ||
− | |04: | + | |04:28 |
− | |For now, if we want to see this list, just type the command echo space dollar PATH | + | |For now, if we want to see this list, just type the command '''echo space dollar PATH ''' in capital. |
|- | |- | ||
− | |04: | + | |04:40 |
− | | | + | |and press '''Enter'''. |
|- | |- | ||
− | |04: | + | |04:45 |
|Talking of commands, there is one important thing that we need to know. | |Talking of commands, there is one important thing that we need to know. | ||
|- | |- | ||
− | |04: | + | |04:51 |
− | |Linux commands are of two types: External commands and internal commands. | + | |Linux commands are of two types: '''External commands''' and '''internal commands.''' |
|- | |- | ||
− | | | + | |04:56 |
− | |Now external commands are those which exist as separate files/programs. | + | |Now '''external commands''' are those which exist as separate files/programs. |
|- | |- | ||
− | |05: | + | |05:00 |
− | |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. | + | |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. |
|- | |- | ||
− | |05: | + | |05:12 |
− | |These are internal commands. | + | |These are '''internal commands. ''' |
|- | |- | ||
− | |05: | + | |05:14 |
− | |The echo command | + | |The '''echo''' command which we will see later, is in fact an '''internal command.''' |
|- | |- | ||
− | |05: | + | |05:18 |
− | |Go to the terminal and type | + | |Go to the '''terminal''' and type the command: |
|- | |- | ||
− | |05: | + | |05:26 |
− | |type space echo and press | + | |'''type space echo''' and press '''Enter'''. |
|- | |- | ||
− | |05: | + | |05:34 |
− | |The output shows echo as a shell built-in. | + | |The output shows: '''"echo as a shell built-in".''' |
|- | |- | ||
|05:43 | |05:43 | ||
− | |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. | + | |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.''' |
|- | |- | ||
− | |05: | + | |05:50 |
|Another important thing which we need to understand is the structure of commands. | |Another important thing which we need to understand is the structure of commands. | ||
|- | |- | ||
− | | | + | |05:55 |
|Commands can be of one word or multiple words, separated by white spaces. | |Commands can be of one word or multiple words, separated by white spaces. | ||
|- | |- | ||
− | |06: | + | |06:02 |
− | |In the second case the first word is the actual name of the command while the other words are the arguments. | + | |In the second case, the first word is the actual name of the command while the other words are the '''arguments.''' |
|- | |- | ||
− | |06: | + | |06:09 |
− | |Arguments can be options or expressions or file names. | + | |'''Arguments''' can be options or expressions or file names. |
|- | |- | ||
− | |06: | + | |06:14 |
|A command can perform different tasks depending on the option specified. | |A command can perform different tasks depending on the option specified. | ||
|- | |- | ||
− | |06: | + | |06:20 |
− | |They are generally preceded by a single or double minus sign | + | |They are generally preceded by a single or double minus sign called short and long option respectively. |
+ | |- | ||
+ | |06:28 | ||
+ | |Go to the '''terminal''' window and type the commands and see their outputs. | ||
|- | |- | ||
− | |06: | + | |06:34 |
− | | | + | |Type '''clear''' to clear the terminal window. |
|- | |- | ||
− | |06: | + | |06:37 |
− | | | + | |Then type '''ls''' and press '''Enter'''. |
|- | |- | ||
− | |06: | + | |06:43 |
− | | | + | |Again, type '''clear''' and press '''Enter'''. |
|- | |- | ||
|06:49 | |06:49 | ||
− | | | + | |Type '''ls space minus a''' and '''Enter'''. |
|- | |- | ||
− | |06: | + | |06:58 |
− | |Type | + | |Type '''clear''' to clear the terminal window. |
|- | |- | ||
|07:04 | |07:04 | ||
− | | | + | |Now type '''ls space minus minus all''' and press '''Enter'''. |
|- | |- | ||
− | |07: | + | |07:13 |
− | | | + | |Again, type '''clear''' to clear the terminal . |
|- | |- | ||
− | |07: | + | |07:18 |
− | | | + | |Now type '''ls space minus d''' and press '''Enter'''. |
|- | |- | ||
− | |07: | + | |07:26 |
− | | | + | |At this point, it is enough to understand how the command's behavior changes with change of options. |
|- | |- | ||
− | |07: | + | |07:33 |
− | | | + | |In Linux, we have a large number of commands |
|- | |- | ||
− | |07: | + | |07:39 |
− | + | ||
− | + | ||
− | + | ||
|each of which have many different options. | |each of which have many different options. | ||
+ | |- | ||
+ | |07:42 | ||
+ | |Commands can also be combined together as we will see later. So, how do we keep so much in mind? | ||
|- | |- | ||
|07:48 | |07:48 | ||
− | | | + | |In reality you don't have to. This is because of the excellent online help facility available in Linux. |
|- | |- | ||
|07:55 | |07:55 | ||
− | | | + | |The '''man''' command provides documentation on just about every available command on the system. |
|- | |- | ||
|08:01 | |08:01 | ||
− | | | + | |For instance, to know about say- the '''ls''' command, all you have to do is to go to the terminal |
|- | |- | ||
− | |08: | + | |08:09 |
− | | | + | |and type '''man''' command with '''ls''' as argument, that is type '''man space ls''' and press '''Enter'''. |
+ | |||
|- | |- | ||
− | |08: | + | |08:23 |
− | | | + | |Press '''q''' to come out. |
|- | |- | ||
− | |08: | + | |08:29 |
− | | | + | |'''man''' is the system’s manual pager. Each argument given to '''man''' is normally the name of a '''program, utility''' or '''function'''. |
|- | |- | ||
− | |08: | + | |08:37 |
− | | | + | |The '''manual page''' associated with each of these '''arguments''' is then found and displayed. |
|- | |- | ||
|08:43 | |08:43 | ||
− | | | + | |A section, if provided, will direct '''man''' to look only in that section of the manual. |
|- | |- | ||
|08:49 | |08:49 | ||
− | |||
− | |||
− | |||
|The default is to search in all of the available sections, following a pre-defined order and to show only the first page found, even if page exists in several sections. | |The default is to search in all of the available sections, following a pre-defined order and to show only the first page found, even if page exists in several sections. | ||
+ | |- | ||
+ | |09:00 | ||
+ | |You can use '''man''' command to know more about the command '''man''' itself. | ||
|- | |- | ||
|09:07 | |09:07 | ||
− | | | + | |Go to the terminal and type '''man space man''' and press '''Enter'''. |
|- | |- | ||
− | |09: | + | |09:16 |
− | | | + | |Press '''q''' to come out of it. |
+ | |- | ||
+ | |09:20 | ||
+ | |'''man''' command has many options. | ||
|- | |- | ||
|09:23 | |09:23 | ||
− | | | + | |Here, let me tell the most useful ones. Sometimes, we know what we want to do but we do not know the exact command. Then what can we do? |
|- | |- | ||
− | |09: | + | |09:35 |
− | |man | + | |'''man''' provides the '''-k''' option which takes a keyword and returns a list of commands and their brief purpose. |
|- | |- | ||
− | |09: | + | |09:44 |
− | | | + | |For example, create a directory; we may not know the exact command. |
− | + | ||
− | + | ||
− | + | ||
|- | |- | ||
|09:50 | |09:50 | ||
− | | | + | | So, we can go to the command prompt and type '''man space minus k space directories''' and press '''Enter'''. |
− | + | ||
− | + | ||
− | + | ||
|- | |- | ||
− | |10: | + | |10:06 |
|Now we can search each of these commands to see what we actually need. | |Now we can search each of these commands to see what we actually need. | ||
|- | |- | ||
− | |10: | + | |10:11 |
− | |The same thing can be achieved using apropos command. | + | |The same thing can be achieved using '''apropos''' command. |
|- | |- | ||
− | |10: | + | |10:15 |
− | |Type at the command prompt apropos space directories and press | + | |Type at the command prompt: '''apropos space directories''' and press '''Enter''' to see the output. |
|- | |- | ||
− | |10: | + | |10:29 |
− | | | + | |Sometimes, we do not need too much details. We only need to know what a command does. |
|- | |- | ||
− | |10: | + | |10:35 |
− | |In that case we can use the whatis command or man -f. Both give one line description about the command. | + | |In that case, we can use the '''whatis''' command or '''man -f.''' Both give one line description about the command. |
|- | |- | ||
− | |10: | + | |10:45 |
− | |Go to the terminal type clear to clear the terminal window | + | |Go to the terminal, type '''clear''' to clear the terminal window. |
|- | |- | ||
− | |10: | + | |10:51 |
− | | | + | |Now, type: '''whatis space ls''' and press '''Enter'''. |
|- | |- | ||
− | | | + | |10:59 |
|Some commands have many options. We may want to obtain a list of the different options that a command has. | |Some commands have many options. We may want to obtain a list of the different options that a command has. | ||
|- | |- | ||
− | |11: | + | |11:07 |
− | |Then we use the minus help option. | + | |Then we use the ''' - - (minus minus) help''' option. |
|- | |- | ||
− | |11: | + | |11:12 |
− | |Go to the command prompt and type ls space minus minus help and press | + | |Go to the command prompt and type '''ls space - -(minus minus) help''' and press '''Enter'''. |
|- | |- | ||
− | |11: | + | |11:23 |
− | |I will scroll up so that | + | |I will scroll up so that you can see all the options on this manual page. |
|- | |- | ||
− | |11: | + | |11:38 |
− | | | + | |That's 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. |
|- | |- | ||
− | |11: | + | |11:49 |
|More information on the same is available at the following link . | |More information on the same is available at the following link . | ||
|- | |- | ||
− | | | + | |11:54 |
− | | This | + | | Thanks for joining us. This is Anuradha Amrutkar, signing off. Good Bye. |
|} | |} |
Latest revision as of 17:46, 10 August 2015
Time | Narration |
00:00 | Dear friends, welcome to a spoken tutorial on the Linux Operating System. |
00:05 | In this tutorial, we will study some basic commands. |
00:10 | I am using Linux Operating System. |
00:12 | We assume that you know how to get started with the Linux operating system. |
00:17 | If you are interested, it is available through another spoken tutorial, on the website [1]. |
00:26 | In this tutorial, we will see what are commands and what is a command interpreter. |
00:33 | Then we will learn about how to find help in Linux using the man command. |
00:39 | Now the first question is, "what are commands?". |
00:43 | In simplest terms we can say that Linux commands are words that when keyed in cause some actions to take place. |
00:51 | Linux commands are seldom more than four character in length, like ls, who, ps etc. |
00:59 | The commands are in lower case and they are case sensitive. Let us see an example . |
01:05 | Go to the Applications menu. |
01:08 | Select Accessories and then click on Terminal from the available options. |
01:14 | Now we can see a prompt ($) and a cursor blinking next to it. This is where we need to type in a command. |
01:22 | Type the word who and press Enter. |
01:28 | We can see the name of the users logged in. Actually we have just executed a command called who which shows who are logged into the system. |
01:41 | But which entity is converting these commands which are nothing more than a few letters into actions? |
01:47 | This is the job of the Command Interpreter, also called the shell. |
01:53 | We can define a shell as a program that acts as the interface between us and the Linux system, |
02:02 | allowing us to enter commands for the operating system to execute. |
02:07 | On Linux it’s quite feasible to have multiple shells installed, with different users able to pick the one they prefer. |
02:16 | 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. |
02:29 | The commands we would be covering in this tutorial are generic and can run on most of the Linux shells with slight variations. |
02:38 | Nevertheless, we would be using the bash as the shell for demonstration in this tutorial. |
02:44 | It is because bash is the most popular shell and portable to almost all UNIX. |
02:52 | Other shells include the Bourne shell which is the original Unix shell, C Shell and the Korn shell. |
03:02 | To see which shell we are using, go to the terminal |
03:08 | and type the command: echo space dollar in capital SHELL and press Enter. |
03:21 | Normally, the output is /bin/bash which gives us the bash shell. |
03:28 | There are ways by which we can activate different shells. Those will be covered in an advanced tutorial. |
03:36 | Commands are actually files containing programs, often written in C. |
03:41 | These files are contained in directories. To find out where a command is stored, we can use the type command. |
03:48 | Type at the command prompt: type space ps and press Enter. |
03:58 | This shows that ps is actually a file, stored in the /bin directory. |
04:03 | When we key in a command at the command prompt, the shell searches for a file matching the command name in a list of directories. |
04:12 | If it is found, then the program corresponding to that file is executed, else a “command not found” error is given. |
04:21 | The list of directories searched is specified by the PATH variable, as we will see later. |
04:28 | For now, if we want to see this list, just type the command echo space dollar PATH in capital. |
04:40 | and press Enter. |
04:45 | Talking of commands, there is one important thing that we need to know. |
04:51 | Linux commands are of two types: External commands and internal commands. |
04:56 | Now external commands are those which exist as separate files/programs. |
05:00 | 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. |
05:12 | These are internal commands. |
05:14 | The echo command which we will see later, is in fact an internal command. |
05:18 | Go to the terminal and type the command: |
05:26 | type space echo and press Enter. |
05:34 | The output shows: "echo as a shell built-in". |
05:43 | 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. |
05:50 | Another important thing which we need to understand is the structure of commands. |
05:55 | Commands can be of one word or multiple words, separated by white spaces. |
06:02 | In the second case, the first word is the actual name of the command while the other words are the arguments. |
06:09 | Arguments can be options or expressions or file names. |
06:14 | A command can perform different tasks depending on the option specified. |
06:20 | They are generally preceded by a single or double minus sign called short and long option respectively. |
06:28 | Go to the terminal window and type the commands and see their outputs. |
06:34 | Type clear to clear the terminal window. |
06:37 | Then type ls and press Enter. |
06:43 | Again, type clear and press Enter. |
06:49 | Type ls space minus a and Enter. |
06:58 | Type clear to clear the terminal window. |
07:04 | Now type ls space minus minus all and press Enter. |
07:13 | Again, type clear to clear the terminal . |
07:18 | Now type ls space minus d and press Enter. |
07:26 | At this point, it is enough to understand how the command's behavior changes with change of options. |
07:33 | In Linux, we have a large number of commands |
07:39 | each of which have many different options. |
07:42 | Commands can also be combined together as we will see later. So, how do we keep so much in mind? |
07:48 | In reality you don't have to. This is because of the excellent online help facility available in Linux. |
07:55 | The man command provides documentation on just about every available command on the system. |
08:01 | For instance, to know about say- the ls command, all you have to do is to go to the terminal |
08:09 | and type man command with ls as argument, that is type man space ls and press Enter. |
08:23 | Press q to come out. |
08:29 | man is the system’s manual pager. Each argument given to man is normally the name of a program, utility or function. |
08:37 | The manual page associated with each of these arguments is then found and displayed. |
08:43 | A section, if provided, will direct man to look only in that section of the manual. |
08:49 | The default is to search in all of the available sections, following a pre-defined order and to show only the first page found, even if page exists in several sections. |
09:00 | You can use man command to know more about the command man itself. |
09:07 | Go to the terminal and type man space man and press Enter. |
09:16 | Press q to come out of it. |
09:20 | man command has many options. |
09:23 | Here, let me tell the most useful ones. Sometimes, we know what we want to do but we do not know the exact command. Then what can we do? |
09:35 | man provides the -k option which takes a keyword and returns a list of commands and their brief purpose. |
09:44 | For example, create a directory; we may not know the exact command. |
09:50 | So, we can go to the command prompt and type man space minus k space directories and press Enter. |
10:06 | Now we can search each of these commands to see what we actually need. |
10:11 | The same thing can be achieved using apropos command. |
10:15 | Type at the command prompt: apropos space directories and press Enter to see the output. |
10:29 | Sometimes, we do not need too much details. We only need to know what a command does. |
10:35 | In that case, we can use the whatis command or man -f. Both give one line description about the command. |
10:45 | Go to the terminal, type clear to clear the terminal window. |
10:51 | Now, type: whatis space ls and press Enter. |
10:59 | Some commands have many options. We may want to obtain a list of the different options that a command has. |
11:07 | Then we use the - - (minus minus) help option. |
11:12 | Go to the command prompt and type ls space - -(minus minus) help and press Enter. |
11:23 | I will scroll up so that you can see all the options on this manual page. |
11:38 | That's 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. |
11:49 | More information on the same is available at the following link . |
11:54 | Thanks for joining us. This is Anuradha Amrutkar, signing off. Good Bye. |