1 00:00:01,150 --> 00:00:07,120 OK so we have discussed theory so let's write some script grade file. 2 00:00:07,230 --> 00:00:15,130 I pleaded as age and on the first line start vade siobhán been Bash. 3 00:00:16,890 --> 00:00:22,940 Now your target is to provide one word or a sentence 4 00:00:27,460 --> 00:00:29,360 as an argument. 5 00:00:31,340 --> 00:00:31,970 To discrete 6 00:00:35,150 --> 00:00:36,830 if in that sentence 7 00:00:40,320 --> 00:00:49,160 there will be IP address. 8 00:00:49,360 --> 00:00:50,320 Find out 9 00:00:56,940 --> 00:00:58,620 if that IP address 10 00:01:01,950 --> 00:01:04,520 is reachable or not. 11 00:01:07,620 --> 00:01:08,730 That means dead. 12 00:01:08,760 --> 00:01:12,460 You need to create a script which takes 1 hour of Blooms-End. 13 00:01:12,630 --> 00:01:20,550 And if that argument is some very present IP address you need to find out if that IP address is reachable 14 00:01:20,640 --> 00:01:21,240 or not 15 00:01:24,270 --> 00:01:26,000 as need exactly one argument. 16 00:01:26,010 --> 00:01:29,380 We can start with that argument check. 17 00:01:29,430 --> 00:01:42,630 So if they are sign Hesh which means number of arguments if it is not equal to them then we can print 18 00:01:44,360 --> 00:01:51,760 ICO provide exactly one argument. 19 00:01:53,610 --> 00:01:54,210 E.g. 20 00:01:56,880 --> 00:02:08,810 the lot of Sanzio which means our escape name and somebody who meant we can also exit with stutterers 21 00:02:08,820 --> 00:02:15,230 of Amina. 22 00:02:15,310 --> 00:02:23,560 Now we can assign first argument to variable Cold War One 23 00:02:27,310 --> 00:02:36,210 and we can now write a regular expression for IP address. 24 00:02:36,230 --> 00:02:39,530 I will also do some comment here. 25 00:02:40,400 --> 00:02:42,950 IP address rhetoric's 26 00:02:46,580 --> 00:02:55,090 So we know that IP address has four part of digits divided by default. 27 00:02:55,440 --> 00:03:03,410 And I think it would be best to write some example here some example of IP address 28 00:03:06,750 --> 00:03:14,230 that is good to know that each part of that IP address can have one up to three digits and digits only. 29 00:03:14,260 --> 00:03:21,630 So first part in the first part we have range 0 2 9 and it will be repeated one to three times. 30 00:03:21,700 --> 00:03:25,970 So I will put one commissary into curly brackets. 31 00:03:25,970 --> 00:03:32,020 Then we have a dot but dot is a special character which means any character so we need to use backslash 32 00:03:32,350 --> 00:03:33,270 before that. 33 00:03:33,370 --> 00:03:41,460 And by that we are telling that this is only Klesko normal dot without any special effects. 34 00:03:41,470 --> 00:03:51,350 Now we can continue the second part which is same as the first one and the same you can do also for 35 00:03:51,460 --> 00:03:52,030 search. 36 00:03:52,060 --> 00:03:52,480 But 37 00:03:56,090 --> 00:04:01,070 so we're in 0 9 and then repeat one to three times 38 00:04:04,200 --> 00:04:05,920 for the fourth part. 39 00:04:05,940 --> 00:04:13,940 We can also instead of orange in square brackets use special character class gold digit. 40 00:04:14,220 --> 00:04:29,580 Discuss with prisons any number and we will also repeat these digit one to three times. 41 00:04:29,940 --> 00:04:41,060 And now we can finally do some regs check to see if indeed argument is IP address provided or not. 42 00:04:41,130 --> 00:04:47,130 So right if an inside square brackets of right where one equals sign 43 00:04:52,420 --> 00:04:54,420 and after equal sign deal done 44 00:04:57,140 --> 00:05:02,730 and our variable that regular expression. 45 00:05:03,200 --> 00:05:07,890 Now we are basically asking if IP address is found and if yes do something. 46 00:05:07,940 --> 00:05:12,750 But that would be to ask immediately if IP is not found. 47 00:05:13,850 --> 00:05:16,170 And in that case it's in disarray. 48 00:05:16,190 --> 00:05:21,870 So for that reason I am putting exclamation mark before square brackets. 49 00:05:22,160 --> 00:05:26,520 Basically I'm doing negation. 50 00:05:26,700 --> 00:05:33,240 So if there is no IP address found we can bring the users ICO. 51 00:05:33,330 --> 00:05:35,860 No IP address provided. 52 00:05:36,210 --> 00:05:41,010 And we can also exit the status to 53 00:05:44,990 --> 00:05:47,440 now if the script won't be exited here. 54 00:05:47,450 --> 00:05:55,760 We are sure that some IP address was found and would be good to store it into variable for example IP 55 00:05:57,500 --> 00:06:01,680 for that we will use for that IP address. 56 00:06:01,760 --> 00:06:13,370 We will use beshe rematch 0 do remember do remember understory I told you about that as they're very 57 00:06:13,480 --> 00:06:22,350 much zero Michie's all those regs we have to specify and be careful how you ride bansuri much as there 58 00:06:22,350 --> 00:06:24,650 are bought Kirtley and square brackets. 59 00:06:26,610 --> 00:06:32,160 Now we need to find if that IP address is reachable or not. 60 00:06:32,490 --> 00:06:33,860 How to do that. 61 00:06:34,200 --> 00:06:36,320 Beeville use Bing. 62 00:06:36,320 --> 00:06:38,360 Come on. 63 00:06:38,430 --> 00:06:45,790 I will firstly write some comment find if IP address is reachable 64 00:06:50,810 --> 00:06:57,350 or not and on the next line we can do basic common 65 00:07:06,210 --> 00:07:10,890 vowed I have here read text which means that something is wrong. 66 00:07:11,280 --> 00:07:16,870 And yes I have mistake in if statement. 67 00:07:16,890 --> 00:07:25,380 I didn't use dollar sign before the rebel so I will just fix it now and we can continue with Bing. 68 00:07:25,410 --> 00:07:34,710 Come on we will ping four times our IP address. 69 00:07:34,890 --> 00:07:36,920 So I really will spin the barometer. 70 00:07:36,980 --> 00:07:37,730 See. 71 00:07:38,000 --> 00:07:42,400 And that barometer C means how many buckets do we want to send 72 00:07:45,250 --> 00:07:46,310 now. 73 00:07:46,770 --> 00:07:58,400 If that ping command was successful vivo assign to variables that those some the message. 74 00:07:58,820 --> 00:08:13,410 So if it is that is zero then we assign it to status variable message alive. 75 00:08:13,780 --> 00:08:24,430 And if ping was not successful we will assign it to that those message that are not reachable 76 00:08:29,780 --> 00:08:34,120 and to now we can print it go 77 00:08:38,320 --> 00:08:40,280 I'd be fine. 78 00:08:40,390 --> 00:08:53,180 And if you specify our IP address us are assigned IP and in parentheses we put our status as the status 79 00:08:53,240 --> 00:08:54,590 of that IP address 80 00:08:57,460 --> 00:08:59,440 we can safely descript 81 00:09:02,440 --> 00:09:11,120 and Grant executive permission we can descript to create one and 82 00:09:19,080 --> 00:09:21,900 all I forgot to properly call descript. 83 00:09:21,900 --> 00:09:23,370 So once they Murra 84 00:09:30,560 --> 00:09:35,630 integrate no IP address provided it works perfectly. 85 00:09:35,780 --> 00:09:40,420 I can try now without any arguments and great. 86 00:09:40,460 --> 00:09:44,800 I have a message to provide exactly one argument. 87 00:09:44,840 --> 00:09:51,110 Now I can try with two arguments and we have to provide exactly one arguments. 88 00:09:51,200 --> 00:09:54,970 Great. 89 00:09:55,130 --> 00:10:06,690 Now let's put as an argument you are a computer localhost IP address and we see the pink output and 90 00:10:06,900 --> 00:10:12,070 at the end we have message IP from the stutterers alive. 91 00:10:12,170 --> 00:10:16,170 Great but I don't like to see that pink output. 92 00:10:16,210 --> 00:10:18,290 Last sentence will be enough. 93 00:10:18,360 --> 00:10:28,920 So I think that we can go back to our script and we will redirect standard output display to screen 94 00:10:29,160 --> 00:10:30,120 to Dev-Null. 95 00:10:30,300 --> 00:10:41,820 So after being command right to him which means standard output and every day the NSA agreed to Dev-Null 96 00:10:45,300 --> 00:10:47,890 thanks to that we won't see any big output. 97 00:10:48,030 --> 00:10:50,120 So let's try this out. 98 00:10:51,150 --> 00:10:59,030 But now as an argument I value some sentence which can represent for example one line from a companion 99 00:10:59,030 --> 00:11:01,840 document with IP addresses description. 100 00:11:02,220 --> 00:11:08,040 And of course if you need to find out if IP address is present here and if it is reachable 101 00:11:11,720 --> 00:11:16,050 so I have specified songs and then with IP address in it 102 00:11:19,710 --> 00:11:29,310 and we can round it and grade b c i be found and it is alive. 103 00:11:29,820 --> 00:11:39,960 So now we can change the sentence to something else and mainly change the idea that has to be not reachable. 104 00:11:52,860 --> 00:11:54,280 Now you need to wait. 105 00:11:54,870 --> 00:11:56,340 And as IP was found. 106 00:11:56,370 --> 00:12:01,630 But it but it is dead not reachable. 107 00:12:01,740 --> 00:12:11,410 Maybe you don't like to wait so long for Pinga to spawn so you can change big barometer of see and then 108 00:12:11,410 --> 00:12:12,720 running again. 109 00:12:15,970 --> 00:12:21,040 So after a few second we should see the exact same response. 110 00:12:21,880 --> 00:12:24,260 That IP was found and it is dead. 111 00:12:25,420 --> 00:12:31,480 So we have now learned how to use regular expressions in our scripts. 112 00:12:31,780 --> 00:12:34,480 And I will wait for you in next lecture.