1 00:00:00,740 --> 00:00:08,400 For a mathematical comparison we can use several operands as equal to not equal to greater than or less 2 00:00:08,400 --> 00:00:13,060 than greater than or equal to less than or equal to. 3 00:00:13,460 --> 00:00:16,850 But how to use them in each state run. 4 00:00:16,890 --> 00:00:18,630 Here are some examples. 5 00:00:18,780 --> 00:00:26,200 In the first we are asking if the value of variables is equal to 5 in the second example. 6 00:00:26,280 --> 00:00:27,500 We are comparing. 7 00:00:27,630 --> 00:00:35,520 If the value of variable of our is greater than 7 and on the last example we have two conditions. 8 00:00:35,520 --> 00:00:46,460 We are comparing If our variable Vohra is equal to 5 and variable count not equal to 1 pre-state era 9 00:00:46,460 --> 00:00:52,190 when writing IF statement because there is a need for a space almost everywhere. 10 00:00:52,340 --> 00:00:59,290 So be careful to not omit based next two brackets and around two operand. 11 00:00:59,440 --> 00:01:04,980 I believe that those slides are good as an introduction for a mathematical comparison. 12 00:01:05,170 --> 00:01:11,630 But let's write some script to see it in practice because only writing scripts makes you an expert. 13 00:01:13,500 --> 00:01:19,560 I will create Scribd riginal do multiplication of two numbers inserted as arguments. 14 00:01:20,040 --> 00:01:21,080 Let's name it. 15 00:01:21,420 --> 00:01:27,790 Multiply two numbers not as H. 16 00:01:34,140 --> 00:01:38,780 On the first line as you go shopping Big Bash 17 00:01:41,700 --> 00:01:42,940 now I sign for it. 18 00:01:42,960 --> 00:01:45,910 I will and two variables first. 19 00:01:48,120 --> 00:01:50,930 And second two variables second. 20 00:01:51,270 --> 00:01:59,370 Second equals do not assign to multiplication can be done using that. 21 00:01:59,660 --> 00:02:10,880 So that result equals first Asterix second and now we can print the result using eco common 22 00:02:13,770 --> 00:02:15,570 equal sign. 23 00:02:15,680 --> 00:02:24,740 First step is dollar signs second equals sign. 24 00:02:24,770 --> 00:02:25,940 Result. 25 00:02:26,360 --> 00:02:33,410 Don't forget on basic rule when we are setting variable we don't use dollar sign in front of them. 26 00:02:33,620 --> 00:02:42,560 But when we want to work with the value of that variable we need to prepare and dollar sign. 27 00:02:42,710 --> 00:02:44,120 Now we can save the file 28 00:02:46,930 --> 00:02:48,860 ground execute permission 29 00:02:51,960 --> 00:03:04,330 and around descript and then we can specify some arguments to and fro for example great result is done. 30 00:03:04,620 --> 00:03:10,380 But what happens if we provide only one argument we see some strange output. 31 00:03:10,450 --> 00:03:20,350 Also if you provide more arguments scrip operate only with first two and skidoos it can be confused. 32 00:03:20,540 --> 00:03:24,840 So what to do social is to have logic in our script. 33 00:03:25,100 --> 00:03:30,020 Doudeville exit script when arguments count is different from two. 34 00:03:30,200 --> 00:03:31,450 Does it make sense. 35 00:03:31,570 --> 00:03:32,240 That's right. 36 00:03:40,570 --> 00:03:46,980 Firstly I will write some command so we know exactly what we are going to do. 37 00:03:49,000 --> 00:03:53,800 Exit the script. 38 00:03:54,050 --> 00:04:02,320 There is more or less done exactly two arguments 39 00:04:05,670 --> 00:04:06,690 on the new line. 40 00:04:06,690 --> 00:04:07,790 Right. 41 00:04:08,010 --> 00:04:15,940 If and break it we know that arguments count can be printed using dollar sign hash. 42 00:04:15,960 --> 00:04:26,400 So not assign a hash not equal to or we can negate this if so instead of not equal right equal and right. 43 00:04:26,490 --> 00:04:29,100 Exclamation mark at the beginning. 44 00:04:33,710 --> 00:04:37,520 Also don't forget spaces in that condition. 45 00:04:37,790 --> 00:04:47,080 So if that condition is true what we want to do we can bring some in from my seat as to arguments needed 46 00:04:49,520 --> 00:04:50,810 around a script 47 00:04:53,380 --> 00:04:57,120 with two arguments. 48 00:04:57,950 --> 00:04:59,570 But death is not all. 49 00:04:59,570 --> 00:05:07,280 If we close here if stateman that command would be still executed and a result result variable would 50 00:05:07,280 --> 00:05:08,690 be printed. 51 00:05:08,690 --> 00:05:10,840 We need to exit scribbly here. 52 00:05:10,970 --> 00:05:16,830 So type exit 2 1 and closed the if statement using f i 53 00:05:23,830 --> 00:05:32,690 now we can save the script and see how it looks like when they're running with three months. 54 00:05:33,850 --> 00:05:42,340 We got a message saying around two arguments are great the same is when we use only one argument for 55 00:05:42,660 --> 00:05:43,280 women's. 56 00:05:43,330 --> 00:05:51,900 It is working perfectly but would happen if one argument is some string bought instead of number we 57 00:05:51,910 --> 00:05:53,600 see stretched out. 58 00:05:54,520 --> 00:05:59,890 But we can get rid of it using exit status to make some change in the script 59 00:06:03,220 --> 00:06:11,080 we can display exit status of all that common exit status of previous command can be displayed using 60 00:06:11,080 --> 00:06:12,190 dollar sign. 61 00:06:12,190 --> 00:06:13,400 Question mark. 62 00:06:13,690 --> 00:06:18,910 So just write equal exit so that those 63 00:06:21,490 --> 00:06:26,780 from all command are assigned. 64 00:06:26,780 --> 00:06:27,750 Question mark 65 00:06:32,130 --> 00:06:40,650 now when we ran the script with string as argument we see that exit status is on when we put only two 66 00:06:40,650 --> 00:06:44,690 numbers as arguments and the status is zero. 67 00:06:44,790 --> 00:06:50,790 We can use this knowledge and the right another condition which will ensure that result is printed if 68 00:06:50,850 --> 00:06:54,220 only two numbers are provided to come on. 69 00:06:54,380 --> 00:07:06,520 That means that we will print this out only if exit status equals zero. 70 00:07:06,530 --> 00:07:12,530 So after that line put another statement 71 00:07:16,050 --> 00:07:27,400 if bracket exits that those dollar sign CAUCHON are not equal to zero. 72 00:07:27,960 --> 00:07:36,430 Then we'll print some message equal. 73 00:07:36,720 --> 00:07:38,220 You need to fold 74 00:07:42,840 --> 00:07:50,150 to integer once ran the script again. 75 00:07:52,420 --> 00:07:57,390 And of course we need to exit here. 76 00:07:57,500 --> 00:08:01,370 I can for example choose at those two 77 00:08:06,070 --> 00:08:08,200 after housekeeper. 78 00:08:08,790 --> 00:08:11,240 I have a printing of resolved 79 00:08:17,890 --> 00:08:29,140 so I will just delete the previously decline and pull back the echo line with the result and close the 80 00:08:29,140 --> 00:08:30,490 if statement using. 81 00:08:30,670 --> 00:08:30,970 I 82 00:08:33,780 --> 00:08:34,770 now save the script 83 00:08:38,250 --> 00:08:41,120 and we can write with two arguments. 84 00:08:41,130 --> 00:08:45,160 It works perfectly when we use think in arguments. 85 00:08:45,480 --> 00:08:46,150 Yeah great. 86 00:08:46,170 --> 00:08:49,040 We have message you need to put two integer. 87 00:08:49,120 --> 00:08:56,730 I want that when we see what is exist at those we see number two 88 00:09:00,890 --> 00:09:13,830 when we use Swee arguments the exist that those is one great and of course the script is working perfectly 89 00:09:14,730 --> 00:09:19,380 to multiply five earfuls then this is the most important thing.