 there on the regular expressions in Linux. So these are the learning outcomes. At end of this session, students will be able to demonstrate the types of regular expressions used in the Linux. So now we will see what you mean by the regular expressions. So the regular expressions are the special characters which help us in searching the data, matching the complex patterns in the string here. Regular expression is the pattern for the matching string that follows the particular pattern. The regular expressions are also called R E G E X P or R E G E X. It is very powerful tools in the Linux. So there are types of regular expressions used in the Linux. So basic are the basic regular expressions, interval regular expressions, extended regular expressions. So now we'll see some basic regular expression. So before starting that some of the commonly used commands with the regular expressions are TR, SED, VI or G R E P. That is the commands. So listed below are the some of the basic reg E X. That is symbol, that is dot, capsulation, dollar, means what it will do. It will replace any character if you make use of the symbol dot. The matches the start of the string if you make use of an encapsulation dollar it matches the end of the string here. So next we are going to see that is on the interval regular expressions. So this expression tells us about the number of occurrence of a characters in the string. They are that is expression curly brackets and so what it does it does the matches the preceding characters appearing n times exactly next n comma m. So what it does the matches the preceding characters appearing n times but not more than m. Next we are going to say that is extended regular expression. So this regular expression contains the combination of one or more than one expressions. That is some of them are that is expression slash plus. So what it does it does the matches one or more occurrence of the previous characters slash a question mark it matches the zero or one occurrence of the previous characters here. Next thing we are going to see the brace expansions. So the brace expansions are useful in doing the scripting of the file year. The syntax used for the brace expansion is one or the other a sequence of comma separated list of items inside the curly brackets as shown in this PPT. So the start and the end items in the sequence are separated by the two periods that is two dots here. So these are the brace expansion here. So now we'll see the demo of all the expressions in the Linux terminal starting from the basic regular expression. So now we'll switch on to the Linux terminal. So we'll see one by one example. So we have to take one the string file. So that is there on the desktop. So the name of that string file is data. So I have created that file and inside that I have kept some string values. So I have kept apple bad balls. So these are the string I have taken inside the data file here. Now we'll see execute the cat command to see the contents of an existing files. So we have already seen that here. So now we'll search the content in containing the letter a. So for that we have to make use of the command that is cat data grade a. So what will happen? So whenever the a appears, so it will show all the strings here. So next what we'll do? So now we'll use the regular expression that is an encapsulation. It matches the start of the string. Let us search the content which starts with the capital A or the small a here. So for that data, Capsulation a. So what does it tell only the line that starts with the characters are filtered, the lines which do not contains the character a at the start are ignored here. So the character starting with a at the starting only they are going to display that the output here. Next, we'll see the interval regular expression here. This expression tells us about the number of occurrence of the characters in the string here. So first we'll filter out all the lines that contains the character P. So same command we have to make use of cat data grape P. So now we'll want to check that the occurrence of P appears exactly two times in the string one after the other. For this, the syntax would be grape minus capital E P slash curly bracket exactly two times we want. So the apple contains the two P here. So that's why only apple has been displayed here. So before using grape P, we have seen the how many P's are occurring in the each string here. So but if you want to an exactly characters P appears at exactly two times in the string. So we have to make use of this command here. So now we'll see the extended regular expression here. This regular expression contains the combination of more than one or two expression here. So first what we'll do we'll search all the characters which contains the T. So for that the command is so these are the string which contains the T. Suppose if you want to filter out the line where the character a preceding the character T here, so we would like to use the command like grape in inverted comma a slash plus T close the bracket here. So now see here the difference between this cat dot txt grape T if you see the where the T is appearing. Now what we have done we want the exactly the whatever the preceding is there after a only T. So there are only two strings are that bat and it here. So now we'll see now the brace expansion how to use in the terminal. So the brace expression we have seen it is in the sequence or the comma separated list of the items that curly bracket shows if you want to do an eco in curly brackets that is separated by the two things that is a comma b comma c. So it will display all the string which are there inside the bracket here a b and c here. Now if you do an eco which contains the two separated dots so we want the range of numbers to be displayed. So for that the commands are from zero dot dot two eleven here. So it will display all the character decimal points which are there from zero one two three four two eleven here. So next we'll see the eco one more example in the brace that is eco a bracket zero two nine. So it will display in this manner that is a zero b a one b here. So these are useful in writing the script. So these are all the expression useful in writing the script here. So now you tell me just which symbol or the special characters are used for the matching the starting the string. So the answer is the caps we have to make use of in caps then only you will be able to sort out the thing which are starting from the matching the string here at the start of the string here. So these are my references. Thank you.