Difference between revisions of "Linux/C3/The-grep-command/English-timed"
From Script | Spoken-Tutorial
(Created page with ' {|border=1 |'''Time''' |'''Narration''' |- |00:01 |Welcome to the spoken tutorial on '''grep''' command |- |00:05 |In this tutorial we will learn '''grep command'''. |- |00…') |
|||
| Line 1: | Line 1: | ||
| − | |||
{|border=1 | {|border=1 | ||
|'''Time''' | |'''Time''' | ||
| Line 34: | Line 33: | ||
|- | |- | ||
|00:32 | |00:32 | ||
| − | |As | + | |As prerequisitesYou should know basics of '''Linux terminal''' |
| − | + | ||
|- | |- | ||
| Line 103: | Line 101: | ||
|02:00 | |02:00 | ||
|Say we want to use '''grep command''', to see who are the students in the '''computers''' stream. | |Say we want to use '''grep command''', to see who are the students in the '''computers''' stream. | ||
| − | |||
|- | |- | ||
| Line 116: | Line 113: | ||
|02:16 | |02:16 | ||
|Now type on the '''terminal''': | |Now type on the '''terminal''': | ||
| − | |||
|- | |- | ||
| Line 150: | Line 146: | ||
|02:46 | |02:46 | ||
|This is because '''grep''' searched for the pattern '''“computers”''' with small '''c''' | |This is because '''grep''' searched for the pattern '''“computers”''' with small '''c''' | ||
| − | |||
|- | |- | ||
|02:52 | |02:52 | ||
|While for '''Zubin''', the stream is “Computers” with a capital '''C'''. | |While for '''Zubin''', the stream is “Computers” with a capital '''C'''. | ||
| − | |||
| − | |||
|- | |- | ||
Revision as of 17:38, 18 July 2014
| Time | Narration |
| 00:01 | Welcome to the spoken tutorial on grep command |
| 00:05 | In this tutorial we will learn grep command. |
| 00:09 | We will do this with the help of some examples. |
| 00:11 | To record this tutorial, I am using |
| 00:15 | *Ubuntu Linux 12.04 Operating System |
| 00:20 | and *GNU BASH version 4.2.24 |
| 00:24 | Please note, GNU bash version 4 or above is recommended to practice this tutorial. |
| 00:32 | As prerequisitesYou should know basics of Linux terminal |
| 00:36 | For relevant tutorials, please visit our website which is as shown. |
| 00:41 | First let us know about regular expressions. |
| 00:45 | *Regular expressions are pattern matching techniques. |
| 00:50 | *When we have to find out whether a pattern exist in a line, paragraph or a file. |
| 00:56 | For ex. If you want to search a phone number in the telephone directory |
| 01:02 | Or To find a keyword in a paragraph or a line, we use grep command.
Let us move on to grep. |
| 01:11 | grep searches for one or more patterns in one or more line, paragraph or a file. |
| 01:17 | If filename is not mentioned, grep search for the patterns in the standard input.
|
| 01:23 | If filename is missing, grep searches for the patterns in the standard input. |
| 01:30 | I will demonstrate usage of grep using a demo file called grepdemo.txt |
| 01:37 | Let us see the content of the file. |
| 01:40 | This is a file that has 13 entries. |
| 01:44 | Each entry has 6 fields roll number, name, stream, marks, and stipend amount. |
| 01:52 | The fields are separated by a bar, which is called a delimiter. |
| 01:56 | Let us see how grep works.
|
| 02:00 | Say we want to use grep command, to see who are the students in the computers stream. |
| 02:07 | For this we have to open the terminal. |
| 02:10 | So press CTRL + ALT and T keys simultaneously on your keyboard. |
| 02:16 | Now type on the terminal: |
| 02:18 | grep space (within double quotes) computers after the double quotes space grepdemo .txt |
| 02:27 | Press Enter |
| 02:28 | This would enlist those entries where stream is computers. |
| 02:33 | Now compare the result with the original file. |
| 02:37 | Come back to our text editor. |
| 02:40 | We see that the entry for Zubin is not enlisted. |
| 02:45 | Why this is so?
|
| 02:46 | This is because grep searched for the pattern “computers” with small c |
| 02:52 | While for Zubin, the stream is “Computers” with a capital C. |
| 02:57 | The pattern matching is case sensitive. |
| 03:00 | To make it case insensitive, we need to use the minus i option with grep. |
| 03:06 | From back to our terminal Now Type:
grep space (minus) i space (within double quotes) “computers” after the double quotes space grepdemo.txt |
| 03:20 | Press Enter. |
| 03:21 | This will now enlist all the four entries. |
| 03:25 | So we saw, grep enlists only those lines of files that match a given pattern. |
| 03:32 | We may do the reverse. |
| 03:34 | It is possible to make grep enlist only those lines that do not match the pattern. |
| 03:40 | For that we have the minus v option. |
| 03:43 | Say, we want to enlist those entries of students who have not passed. |
| 03:48 | We can also store this result in another file
|
| 03:52 | For this type:
grep space minus iv space Within double quotes pass after the double quotes space grepdemo.txt space greater than sign space notpass.txt |
| 04:11 | Press Enter. |
| 04:12 | To see the content of file, type:
cat space notpass.txt |
| 04:20 | Press Enter. |
| 04:21 | The output is displayed. |
| 04:24 | Now at the prompt type: |
| 04:26 | grep space minus i space' within double quotes fail after the double quotes space grepdemo.txt |
| 04:37 | And Press Enter. |
| 04:38 | This is different.
|
| 04:41 | This will include those students who are failed but their result is incomplete.
|
| 04:46 | If we want to see the line number in the file at which the enlisted entries are, we have the minus n option
|
| 04:54 | Let us clear the prompt. |
| 04:58 | Now type "grep space -in space within double quote "fail" after the double quotes space grepdemo.txt |
| 05:09 | Press Enter. |
| 05:11 | The line number is displayed. |
| 05:15 | The patterns so far have been of single word. |
| 05:18 | We may have multiword patterns as well. |
| 05:21 | But the entire pattern must be within quotes. |
| 05:24 | So type: grep space minus i spacewithin double quotes ankit space saraf after the double quotes space grepdemo.txt |
| 05:38 | Press Enter. |
| 05:40 | We see that Ankit Saraf's record is displayed. |
| 05:44 | We can also find patterns in multiple files.
|
| 05:48 | For this Type:
grep space minus i space within double quotes fail after double quotes space grepdemo.txt space notpass.txt
|
| 06:03 | Press Enter. |
| 06:04 | The output is displayed.
|
| 06:07 | With multiple files, grep will write the name of the file in which the entry was found.grepdemo.txt and notpass.txt |
| 06:18 | These are the records from notpass.txt file and these are the records from grepdemo.txt file. |
| 06:26 | Suppose we may only want to know the number of matches or count . |
| 06:31 | For that, we have the minus c option
|
| 06:35 | So Type: grep space minus c spacewithin double quotes Fail with a capital F after the quotes space grepdemo.txt |
| 06:48 | Press Enter. |
| 06:50 | This will give us the count of number of lines matched. |
| 06:55 | This brings us to the end of this tutorial.
|
| 06:59 | Let us summarize. |
| 07:01 | In this tutorial we learnt, |
| 07:03 | *To see the content of a file
|
| 07:07 | *To list the entries of a particular stream
|
| 07:14 | *To ignore cases
|
| 07:21 | *Lines that do not match the pattern
|
| 07:30 | *To list the line numbers with the entries
|
| 07:38 | *To store the result in another file
|
| 07:50 | And*To know the count
|
| 07:57 | As an assignment, |
| 07:58 | Explore some other commands like -E, + and ?
|
| 08:04 | Watch the video available at the link shown below. |
| 08:06 | It summarises the Spoken Tutorial project. |
| 08:10 | If you do not have good bandwidth, you can download and watch it. |
| 08:14 | The Spoken Tutorial Project Team |
| 08:16 | *Conducts workshops using spoken tutorials |
| 08:19 | *Gives certificates to those who pass an online test |
| 08:23 | For more details, please write to
contact@spoken-tutorial.org |
| 08:30 | Spoken Tutorial Project is a part of the Talk to a Teacher project |
| 08:33 | It is supported by the National Mission on Education through ICT, MHRD, Government of India |
| 08:40 | More information on this Mission is available at: http://spoken-tutorial.org\NMEICT-Intro |
| 08:45 | This is Ashwini Patil from IIT Bombay signning off. Thank you for joining. |
