1 00:00:02,580 --> 00:00:09,710 In this lecture we are going to create a script which can take some parameters so create a file called 2 00:00:09,710 --> 00:00:10,650 file check. 3 00:00:10,730 --> 00:00:16,070 As a start with siobhán on the first line 4 00:00:19,750 --> 00:00:23,610 and on the next line we can write what we are going to build. 5 00:00:23,800 --> 00:00:34,240 So write command write script which will work with parameters 6 00:00:37,670 --> 00:00:50,300 and it will be Desch F or dash file which will provide info about number of lines vorwärts and characters 7 00:00:50,360 --> 00:00:51,290 of some file 8 00:01:04,670 --> 00:01:10,000 of lines vorwärts and characters 9 00:01:13,100 --> 00:01:19,760 and we can also use Sparham meter dash age or dash dash help 10 00:01:25,620 --> 00:01:34,750 and these will provide each message so one time aura. 11 00:01:34,990 --> 00:01:43,680 The goal is to build our script with some barometers parameter or parameter file will take a value of 12 00:01:43,760 --> 00:01:49,990 a file pop and it will print a number of lines voids and characters in that file. 13 00:01:51,010 --> 00:01:56,120 Parameter age or a parameter or help will print usage of message. 14 00:01:56,180 --> 00:02:00,230 That means message how to use our script. 15 00:02:00,460 --> 00:02:07,810 So if you want to check what parameters were added We basically need to loop through all arguments so 16 00:02:07,840 --> 00:02:09,220 let's do it. 17 00:02:09,220 --> 00:02:11,000 We will use a while loop. 18 00:02:11,050 --> 00:02:18,020 So while a number of arguments are represented as a sign hash is greater than zero. 19 00:02:18,280 --> 00:02:23,720 Then perform commands between do and keyboards. 20 00:02:23,760 --> 00:02:30,840 Now we should check what is the first argument and for that reason we can use case statement. 21 00:02:31,100 --> 00:02:33,470 So case dollar sign or one 22 00:02:36,470 --> 00:02:38,270 in. 23 00:02:38,430 --> 00:02:47,460 So if the first argument is that age or degradation of legal pre-NDA usage message 24 00:02:57,150 --> 00:03:01,860 so this will override echo usage. 25 00:03:02,120 --> 00:03:12,620 Dollar Signs 0 which is the screen name and then the possibilities user has Desch H or does it help 26 00:03:14,090 --> 00:03:19,090 Desch efile or dash dash file followed by file pop 27 00:03:24,130 --> 00:03:27,920 and we can also exit discretely here as user. 28 00:03:27,930 --> 00:03:30,190 Don't know how to use the script that 29 00:03:34,500 --> 00:03:47,070 if the first arable land is Desch f or a dash dash file we should store a given file apart into variable 30 00:03:47,070 --> 00:03:53,760 file so I the lot of to into viable file 31 00:03:56,950 --> 00:04:05,160 but why we are using here go are assigned to because we are expecting to get filed back right after 32 00:04:05,160 --> 00:04:13,740 a user specified dish or Dish dish file but what happens if after dish or Dish dish file is not efile 33 00:04:13,850 --> 00:04:19,090 path we need to check if a file really exists. 34 00:04:19,660 --> 00:04:20,850 So we'll see. 35 00:04:20,890 --> 00:04:30,850 Using filed this update F and if that file doesn't exist we will print the file not exit's 36 00:04:34,860 --> 00:04:38,490 so eco file 37 00:04:41,300 --> 00:04:47,900 does not exits and will exit the script with exit status to 38 00:04:52,260 --> 00:04:59,130 now if we have existing file we need to find out how many lines of words and characters in the file 39 00:04:59,130 --> 00:04:59,820 has. 40 00:05:00,120 --> 00:05:10,030 So for all lines we will use command WC vate barometer our So lines for us. 41 00:05:10,250 --> 00:05:19,920 Cut the file and output of that cut command will give into standard input of command W see 42 00:05:23,420 --> 00:05:31,230 four of our ads will use command debri will see with meter W 43 00:05:42,740 --> 00:05:44,450 and for correctors 44 00:05:47,260 --> 00:05:51,150 it will be the same bandwidth parameter and 45 00:06:00,650 --> 00:06:08,100 but because we are assigning to a variable output of command we need to do command substitution. 46 00:06:08,300 --> 00:06:09,980 And I will do that. 47 00:06:09,980 --> 00:06:17,550 For example using batiks. 48 00:06:17,640 --> 00:06:25,470 Now we can print to user information about a number of lines of words and characters. 49 00:06:25,560 --> 00:06:29,070 So start with printing file name 50 00:06:33,220 --> 00:06:37,010 file Galarza on file. 51 00:06:38,980 --> 00:06:42,120 Then we can print number of lines 52 00:06:46,220 --> 00:06:53,240 so it got lines and this is two dollar sign lines. 53 00:06:53,240 --> 00:07:03,700 Then we can print number of boards so a number of words is represented by variable Lords. 54 00:07:05,270 --> 00:07:12,830 And then we can print number of characters which is represented by the characters 55 00:07:17,220 --> 00:07:17,780 we. 56 00:07:17,800 --> 00:07:21,550 And this case section using doubles and column 57 00:07:30,870 --> 00:07:35,620 and for a case that user will type something different. 58 00:07:35,700 --> 00:07:42,210 We are using asterisk which is a wildcard representation of any number of characters. 59 00:07:42,840 --> 00:07:53,680 And here we can be lazy and just use each line read Exit command and close the section using double 60 00:07:53,680 --> 00:07:56,180 semicolon. 61 00:07:56,330 --> 00:08:02,570 Now we can close the case statement all suck. 62 00:08:03,920 --> 00:08:08,880 But if you are looking carefully something is not right. 63 00:08:08,930 --> 00:08:14,090 We are at the beginning asking if number of arguments is greater than zero. 64 00:08:14,480 --> 00:08:18,230 But number of arguments is still the same and not changing. 65 00:08:18,440 --> 00:08:26,120 It would be nice to decrease the number of arguments after reports as arguments in case section and 66 00:08:26,120 --> 00:08:32,290 to our surprise we have such an option and it is using keyword shift. 67 00:08:32,830 --> 00:08:40,640 Every Varietes shift we are drawing ever a first argument so that means if we for example have five 68 00:08:40,640 --> 00:08:50,430 arguments and then brightened the first Tuvan is throw away and we have only four arguments so far. 69 00:08:50,450 --> 00:08:52,590 Desch F and dash dash. 70 00:08:52,670 --> 00:08:54,080 File S.. 71 00:08:54,140 --> 00:08:58,640 We need to throw away that argument which represents parameter 72 00:09:03,530 --> 00:09:04,700 throw a 73 00:09:10,280 --> 00:09:15,290 parameters argument and also we need to throw away 74 00:09:18,070 --> 00:09:23,150 debt at a woman which is your presence file but 75 00:09:25,900 --> 00:09:27,690 that parameter is the value. 76 00:09:28,180 --> 00:09:36,130 So if user specified only Desch f followed by some file pop we now don't have any argument. 77 00:09:36,250 --> 00:09:46,770 And while we'll finish with this loop Eevee didn't have in the Help section exit commom We also would 78 00:09:46,770 --> 00:09:54,880 need to use command shift which will throw every argument which is represented by parameter Desch age 79 00:09:55,330 --> 00:09:58,990 or dash dash help. 80 00:09:59,240 --> 00:10:06,440 And in this section is not needed as help parameter is not followed by any value as it was in the file 81 00:10:06,480 --> 00:10:08,800 parameter. 82 00:10:08,830 --> 00:10:12,960 So one time more for the case user has specified. 83 00:10:13,090 --> 00:10:17,000 Or does this file followed by file path. 84 00:10:17,200 --> 00:10:24,920 We need to throw away two arguments as we don't want to come across those arguments again as Dave already 85 00:10:24,940 --> 00:10:32,750 puts us and forecast user specified Desch age or Degesch help we need to fro. 86 00:10:32,860 --> 00:10:40,240 Only one argument as is debt argument was already processed and we don't want to come across with it 87 00:10:40,420 --> 00:10:42,530 again. 88 00:10:42,580 --> 00:10:48,820 So now we can close the script ground execute permissions 89 00:10:53,050 --> 00:10:54,580 and run discrete 90 00:10:59,860 --> 00:11:04,950 but firstly let's see what we can read in the current directory. 91 00:11:04,960 --> 00:11:15,620 You'll see us so I will try to check that employee file from previous lecture and can see that I did 92 00:11:15,620 --> 00:11:18,740 it wrongly as I didn't specify file Paromita. 93 00:11:18,860 --> 00:11:22,540 So I have received the message. 94 00:11:22,610 --> 00:11:31,250 If I use parameter file with employee file I received the file stat.. 95 00:11:31,350 --> 00:11:32,240 Great. 96 00:11:32,350 --> 00:11:38,160 I see 8 lines for divorce and 199 characters. 97 00:11:38,340 --> 00:11:39,290 Great. 98 00:11:40,000 --> 00:11:45,890 If I change file to some not existing I receive file doesn't exist. 99 00:11:45,940 --> 00:11:47,120 Great. 100 00:11:47,140 --> 00:11:56,230 Now I will try to change parameters Dish dish file to Desch F and I will also art Dish dish help. 101 00:11:59,760 --> 00:12:02,100 So I am using two buy meat that is either 102 00:12:04,970 --> 00:12:06,320 and great. 103 00:12:06,320 --> 00:12:08,280 I can see firer stat.. 104 00:12:08,360 --> 00:12:14,060 And also I can see using message because I have also specified help barometer. 105 00:12:14,870 --> 00:12:22,010 So at the beginning of our script letter asking if number of arguments is greater than zero and it was 106 00:12:22,070 --> 00:12:30,600 we have three arguments then we went into K.S. and started to ask what is the first argument. 107 00:12:30,800 --> 00:12:33,030 First argument was Desch have. 108 00:12:33,140 --> 00:12:39,900 So we have prepared for our statistics for a second argument which has employee file. 109 00:12:40,120 --> 00:12:48,040 Then we have used shift 2 times which means that we get rid of Desch F and also we get rid of employee 110 00:12:48,040 --> 00:12:49,270 file. 111 00:12:49,300 --> 00:12:53,850 Now we have only one argument and it is Desch doesn't help. 112 00:12:54,280 --> 00:13:00,740 The script goes again from the beginning and asking Is number of arguments greater than zero. 113 00:13:01,030 --> 00:13:01,910 Yes it is. 114 00:13:01,930 --> 00:13:05,520 We have one argument that doesn't help. 115 00:13:05,560 --> 00:13:12,310 So we then go to the K section where we are asking for the first argument which is now help. 116 00:13:12,520 --> 00:13:19,330 And in that case we are printing usage message and exiting with Aristotle's one. 117 00:13:19,810 --> 00:13:26,320 If it didn't use exit command here we still have the shift to come on here which would throw away the 118 00:13:26,320 --> 00:13:27,490 first argument. 119 00:13:27,640 --> 00:13:29,670 In our case Desch didn't help. 120 00:13:29,800 --> 00:13:36,250 And then the script would continue to the beginning of viable where we are asking is the number of arguments 121 00:13:36,250 --> 00:13:37,960 greater than zero. 122 00:13:37,960 --> 00:13:38,970 No it isn't. 123 00:13:38,980 --> 00:13:40,980 We have zero arguments now. 124 00:13:41,080 --> 00:13:49,960 So the script would continue after dummy keyboard of vital. 125 00:13:49,980 --> 00:13:57,130 Now we can check some bigger file for example passport file and it works nice. 126 00:13:57,620 --> 00:14:03,680 So in this way you can create your own script with numerals but ammeters.