BOSS-Linux/C3/Basics-of-awk/English-timed

Time	Narration
00:01	Welcome to the spoken tutorial on the awk command.
00:05	In this tutorial we will learn, awk command.
00:09	We will do this through some examples.
00:12	To record this tutorial, I am using Linux Operating system GNU BASH v. 4.2.24
00:21	Please note, GNU Bash version 4 or above is recommended to practice this tutorial.
00:29	Let us start with an introduction to awk.
00:32	The awk command is a very powerful text manipulation tool.
00:36	It is named after its authors, Aho, Weinberger and Kernighan.
00:42	It can perform several functions.
00:46	It operates at the field level of a record.
00:49	So, it can easily access and edit the individual fields of the record.
00:56	Let us see some examples.
00:58	For demonstration purpose, we use the awkdemo.txt file.
01:03	Let us see the contents of awkdemo.txt file.
01:07	Now open the terminal window
01:10	Let us see how to print using awk command.
01:15	Type: awk space (within single quote) (front slash) ‘/Pass (front slash)/(opening curly bracket) {print (closing curly bracket)} (after the quotes) space awkdemo.txt
01:32	Press Enter
01:34	Here Pass is the selection criteria.
01:38	All the lines of the awkdemo where Pass occurs are printed.
01:43	The action here is print.
01:46	We can also use regular expressions in awk
01:50	Say we want to print records of students with name Mira.
01:55	We would type: awk space '/M opening square bracket ei closing square bracket asterisk sign ra asterisk sign front slash opening curly bracket print closing curly bracket after the quoates space awkdemo.txt
02:20	Press Enter.
02:22	"*(asterisk)" will give one or more occurrences of previous character.
02:27	Thus entries with more than one occurrence for i, e and a will be listed.
02:34	For example
02:35	Mira (with 'M' 'I' 'R' 'A')
02:38	Meera(with 'M' 'E' 'E' 'R' 'A')
02:41	*Meeraa(with M E E R A A )
02:45	awk supports the extended regular expressions (ERE).
02:51	Which means we can match multiple patterns separated by a PIPE.
02:56	Let me clear the promt
02:59	Now type:
03:00	electrical (front slash)space (open curly brackets)/{print}(close curly brackets) after the quotes spaceawkdemo.txt
03:18	Press Enter.
03:19	Now entries for both civil and electrical are given.
03:24	Let us go back to our slides.
03:28	Parameters awk has some special parameters to identify individual fields of a line.
03:36	$1(Dollar 1) would indicate the first field.
03:40	Similarly we can have $2, $3 and so on for respective fields.
03:47	$0 represents the entire line.
03:50	come back to our terminal
03:52	Note that each word is separated by PIPE in the file awkdemo.txt.
03:59	In this case PIPE is called a delimiter.
04:03	A delimiter separates words from each other.
04:06	A delimiter can also be a single whitespace.
04:11	To specify a delimiter, we have to give - capital F flag followed by a delimiter.
04:18	Let us see
04:19	Type awk space minus capital F space within double quotes PIPE space within single quote front slash civil PIPE electrical front slash opening curly bracket print space dollar0 closing curly braket after the quotes space awkdemo.txt
04:44	Press Enter
04:46	This print the entire line since we have used $0.
04:52	Notice that, names and stream of students are the second and third fields.
04:58	Say we only want to print two fields.
05:01	We will replace $0 with $2 and$3 in the above command.
05:09	Press Enter
05:11	Only two fields are shown.
05:14	Though it gives the right result, the display is all jagged and unformatted.
05:20	We can provide formatted output by using the C style printf statement.
05:26	We can also provide a serial number by using a builtin variable NR.
05:33	We will see more about builtin variables later.
05:37	Now Type awk space minus capital F within double quotes (Pipe)” after the double quotes space 'front slash Pass front slash opening curly bracket printf within double quotes percentage sign 4d space percentage sign -25s space percentage sign minus 15s space backslash n”, after the double quotes NR,$2,$3 closing curly bracket' after the single quote space awkdemo.txt
06:25	Press Enter.
06:28	We see the difference.
06:30	Here the NR stands for number of records.
06:33	Records are integers, hence we have written %d.
06:37	Name and Stream are strings. So we have used %s.
06:43	Here 25s will reserve 25 spaces for Name field.
06:48	15s will reserve 15 spaces for Stream field.
06:54	The minus sign is used to left justify the output.
06:58	This brings us to the end of this tutorial.
07:01	Let us move back to our slides.
07:04	Let us summarize.
07:05	In this tutorial we learnt To print using awk
07:10	Regular expression in awk. To list the enteries for a paritcular stream
07:15	To list only the second and the third fileds
07:18	To display a formatted output
07:19	As an assignment
07:22	Display roll no., stream and marks of Ankti Saraf
07:27	Watch the video available at the link shown below
07:30	It summarises the Spoken Tutorial project
07:33	If you do not have good bandwidth, you can download and watch it
07:37	The Spoken Tutorial Project Team Conducts workshops using spoken tutorials
07:42	Gives certificates to those who pass an online test
07:45	For more details, please write to contact@spoken-tutorial.org
07:51	Spoken Tutorial Project is a part of the Talk to a Teacher project
07:55	It is supported by the National Mission on Education through ICT,MHRD,Government of India
08:02	More information on this Mission is available at: [1]
08:07	This is Ashwini Patil from IIT Bombay signning off. Thank you for joining.

Contributors and Content Editors

PoojaMoolya, Pratik kamble, Sandhya.np14