BOSS-Linux/C2/Simple-filters/English-timed

Time	Narration
00:02	Hello and welcome to the Spoken Tutorial on Simple Filters with Linux.
00:09	Here we will be learning about head, Tail, sort, cut and paste.
00:18	All these are command line text manipulation tools.
00:22	If you see a hash (#) symbol on the Terminal you need to become root to execute those commands
00:29	sudo su or su root, if you see a dollar symbol on the Terminal you can be an ordinary user to execute those commands.
00:38	I assume that you did a default installation and did not modify any path where the files are getting saved.
00:46	I am using Linux for this tutorial.
00:51	Prerequisites for this module are the ability to use the mouse , keyboard, maximize and minimize buttons on a window.
01:02	We use the Head command followed by an ascii file name, to display the first 10 lines of a file by default.
01:10	Let us create a file.
01:13	Go to Applications > Accessories > Text Editor.
01:20	I already have these numbers in another file for the sake of time constrain .
01:26	Let me copy and paste.
01:34	Hit on File , Save.
01:37	Name the file as numbers dot txt and hit on save
01:44	Close this file.
01:50	Now go to Applications > Accessories > Terminal.
01:58	Let us try to see if we can see the file we created.
02:02	Type ls and hit on enter.
02:05	What we did here is to list all the folders and files on our home directory.
02:11	Now we can use the cat command to read the contents of the file we created.
02:18	Cat n-u-m Hit on tab to autofill the file name. Hit on Enter.
02:26	Let us do the same with head command.
02:30	head numbers dot txt, enter
02:36	Now the first 10 lines are displayed.
02:39	If we want to see the first 5 lines, use the option hyphen n5 in between the head command and the file.
02:49	Hit on Up arrow, hyphen n5 and Enter.
02:55	Now the first 5 lines alone are displayed.
02:59	Let us switch back to the presentation
03:04	The tail command works exactly opposite to the head command, it displays the last 10 lines of a file by default.
03:12	I am hitting on ALT and Tab to switch to the terminal.
03:17	tail numbers dot txt
03:21	If we want to see just the last 5 lines, use the option hyphen n5 in between the tail command and the file name.
03:31	hyphen n5, Enter
03:36	Switch to slides
03:39	A log file contains events which took place in a system.
03:45	Auth dot log file maintains log's for who logged in & who logged out.
03:51	The most useful option of the tail command is to use hyphen f option to follow the tail of a log file.
03:59	If a new line is appended to the log file, the tail command will take that as the last line and display 10 lines by default above it.
04:09	Go to the terminal
04:11	tail hyphen f forward slash var slash log slash auth dot log
04:21	Let me resize this terminal
04:28	Let us open another Terminal , Application- > Accessories - > Terminal.
04:36	Let me resize this terminal
04:42	so that I can show you in a single screen how tail follows the last line in a log file.
04:50	Try to su as yourself, hit on enter.
04:54	Give in some wrong password hit on enter.
04:58	You will see that the terminal on which tail is running is appended with a new log.
05:05	The date & time specifies when the authentication failure took place.
05:13	Type date hit on enter to verify the system date and time.
05:22	Type Exit to close this terminal.
05:26	Hit CTRL C to close the running tail command & maximize the screen.
05:42	We have seen only auth dot log file in the previous example.
05:47	These are the commonly used log files in Linux.
05:51	A linux system administrator will look into these log files for more information to troubleshoot his machine if there is a problem.
06:02	Sort command as the name suggest will sort a file for us in both ascending and descending order.
06:13	sort numbers dot txt .This would sort our numbers dot txt file in ascending order.
06:21	Notice something is strange in there, sort just looks at the first character to sort, so 10,11&12 appears before the number 2.
06:33	To avoid this add the option of hyphen n, hyphen n and Enter
06:43	Now sort looks at the entire number to sort them.
06:47	To sort number dot txt in reverse order add an option of hyphen r.
06:59	We have numbers that repeat in this file, to pull out just the unique numbers add another option of hyphen u .
07:07	Go to Terminal.
07:09	Up Arrow
07:11	U, enter,
07:15	Previously two 2's were displayed . Now only one 2 is displayed.
07:28	Now we will see how we can sort a file based on certain column.
07:33	Let us create a file and key in these as shown below.
07:38	Go to Applications > Accessories > Text Editor.
07:46	I already have the data in another file for the sake of time constrain let me copy & Paste the value, CTRL+C; CTRL+V.
08:01	File, Save it as marks dot txt, Hit on Save.
08:11	Don't mind the special characters on this file I don't want someone to sue me for giving them low marks
08:18	Close this file.
08:24	Let us sort based on the second column of marks dot txt file.
08:30	Go to the terminal.
08:32	sort space marks dot txt space hyphen t space open inverted commas space close inverted commas space
08:43	here hyphen t stands for the delimiter & the space in between the quotes represents it.
08:52	hyphen k2 for the second column on which sort should be performed.
09:04	Hit on Enter.
09:10	Cat marks dot txt
09:14	This is the original file, if you see Avir is moved above and Bala came below when we sorted based on the second column alone.
09:33	Cut command is used to cut just certain information from a file.
09:41	Let us pull out the names from marks dot txt
09:44	Let us go to the terminal ALT Tab
09:48	cut space marks dot txt space hyphen d space open inverted commas space close inverted commas space.
09:58	here in cut command d is the delimiter & the space in between the quotes represents the delimiter.
10:10	hyphen f2 for the second column. Hit on enter.
10:21	Paste command will merge corresponding subsequent lines of the files.
10:26	Let us use both the numbers dot txt and marks dot txt file now.
10:31	Go to the terminal.
10:33	Paste numbers dot txt marks dot txt, enter
10:40	Now the first line of marks dot txt was appended to the first line of numbers dot txt.
10:47	We can use the redirect key to redirect this output to some other file called concatefile dot txt.
10:56	Go to the terminal.
10:58	Hit on Up arrow. Hit on the redirect key which is the Greater than symbol concatfile dot txt. Hit on Enter.
11:07	Cat concatfile dot txt
11:12	Let us go to the slide.
11:15	If we want paste to print out the numbers serially delimited with tab we can use the hyphen s option.
11:25	Paste hyphen s
11:29	numbers dot txt
11:33	Go to the slide.
11:34	Spoken Tutorial project is a part of Talk to a Teacher project,
11:39	Supported by the National Mission on Education through ICT,MHRD, Government of India.
11:45	For more information you can refer to the following link.
11:48	This is Bala. Thanks a lot for watching this video and dont forget to leave a comment.

Contributors and Content Editors

PoojaMoolya, Pratik kamble, Sandhya.np14