1
00:00:00,000 --> 00:00:01,110
[No audio]

2
00:00:01,110 --> 00:00:03,870
As we are continuing to the text processing

3
00:00:03,870 --> 00:00:07,920
commands, we will go over the grep and egrep

4
00:00:07,920 --> 00:00:10,920
commands that is also as one of the powerful

5
00:00:10,920 --> 00:00:14,640
commands in terms of text processing. So what

6
00:00:14,640 --> 00:00:19,260
exactly is a grep. The grep command which stands

7
00:00:19,260 --> 00:00:23,130
for global regular expression print, processes

8
00:00:23,130 --> 00:00:26,940
texts line by line, and prints any lines which

9
00:00:26,940 --> 00:00:32,369
match a specified pattern. So basically in simple

10
00:00:32,369 --> 00:00:36,210
words, it's a search technology or a search

11
00:00:36,210 --> 00:00:40,470
feature in Linux that allows you to search for a

12
00:00:40,470 --> 00:00:44,970
specific feature or specific keyword actually, sorry

13
00:00:44,970 --> 00:00:48,810
not feature a specific keyword that you look for

14
00:00:49,080 --> 00:00:54,750
in a file or an output from a command. So let's

15
00:00:54,750 --> 00:00:57,510
get into a Linux machine and I will show you a few

16
00:00:57,510 --> 00:01:00,090
of the commands and examples. So this way you have

17
00:01:00,090 --> 00:01:02,490
a better understanding how the grep or egrep

18
00:01:02,490 --> 00:01:06,209
command works. I have my Linux machine right here

19
00:01:06,239 --> 00:01:11,160
open and again I am logged in as myself, the

20
00:01:11,160 --> 00:01:16,380
machine, the hostname is MyFirstLinuxVM and

21
00:01:17,460 --> 00:01:21,290
which directory I am in, I am in /home/iafzal.

22
00:01:21,290 --> 00:01:23,310
Now one thing I do want to tell you, you're probably

23
00:01:23,310 --> 00:01:25,770
thinking to yourself, hey why Imran alway runs

24
00:01:25,770 --> 00:01:29,460
whoami, and hostname when he sees himself here,

25
00:01:29,670 --> 00:01:32,970
as iafzal, and right here is hostname? The

26
00:01:32,970 --> 00:01:37,770
reason I do that is because a lot of systems, when

27
00:01:37,770 --> 00:01:39,600
you're going to get into the corporate world, a

28
00:01:39,600 --> 00:01:43,050
lot of systems not going to have this type of

29
00:01:43,050 --> 00:01:45,720
prompt, they're probably going to show you either

30
00:01:45,750 --> 00:01:49,500
this symbol or the hashtag. So you're probably not

31
00:01:49,500 --> 00:01:51,670
going to know whether you're logged in as iafzal,

32
00:01:51,670 --> 00:01:53,400
or you're going to logged into the right

33
00:01:53,400 --> 00:01:55,950
machine. But if you do see it perfect, that's

34
00:01:55,950 --> 00:01:59,010
great. But if you don't, that's why I want you to

35
00:01:59,010 --> 00:02:03,240
get used to have these few commands, whoami,

36
00:02:03,240 --> 00:02:05,520
hostname, and which directory you are in before

37
00:02:05,520 --> 00:02:07,650
you start making any changes to your system.

38
00:02:08,100 --> 00:02:11,610
Anyway, let's clear the screen. And the first

39
00:02:11,610 --> 00:02:14,550
command we will run for grep, as always check the

40
00:02:14,550 --> 00:02:17,940
version and check for help. So for grep dash dash

41
00:02:17,940 --> 00:02:21,180
version, it will give you the version and now you

42
00:02:21,180 --> 00:02:24,180
could read it, you know where to find the version.

43
00:02:24,420 --> 00:02:27,180
The next one is grep dash dash help. This will

44
00:02:27,180 --> 00:02:31,110
give you all the information about the grep and

45
00:02:31,170 --> 00:02:36,210
its options. If you want to get a quick list of

46
00:02:36,210 --> 00:02:38,220
all the options that are available, you always use

47
00:02:38,220 --> 00:02:42,990
grep dash dash help, if you want to get the longer

48
00:02:42,990 --> 00:02:47,040
description or have every option, you could use

49
00:02:47,040 --> 00:02:51,360
man and do grep, and this will give you a detailed

50
00:02:51,360 --> 00:02:55,410
information about the grep command. Anyway, so we

51
00:02:55,410 --> 00:02:57,720
know the version, we know how to get help, and now

52
00:02:57,720 --> 00:03:01,560
let's get to this second lab question which is to

53
00:03:01,560 --> 00:03:05,850
search for a keyword in a file. So I am in my home

54
00:03:05,850 --> 00:03:08,520
directory. I'll go back to the seinfeld directory,

55
00:03:08,550 --> 00:03:11,250
in there I have a file called seinfeld-characters

56
00:03:11,280 --> 00:03:15,360
we'll cat it out, and these, this are the contents of

57
00:03:15,360 --> 00:03:19,320
the seinfeld directory. Okay, so now if I just

58
00:03:19,320 --> 00:03:25,170
clear the screen, go back up, and what I will do is I

59
00:03:25,170 --> 00:03:30,817
will grep for Seinfeld, in the filename

60
00:03:30,817 --> 00:03:35,010
seinfeld-characters. It means only give me the

61
00:03:35,010 --> 00:03:37,380
lines there matches the word Seinfeld.

62
00:03:37,680 --> 00:03:39,930
When I hit enter, there are two lines that match

63
00:03:39,930 --> 00:03:43,920
the word Seinfeld, which is Jerry Seinfeld and

64
00:03:43,920 --> 00:03:47,460
Morty Seinfeld. I could, same way I could do with

65
00:03:47,490 --> 00:03:50,130
other files as well. Let's say if I want to grep

66
00:03:50,130 --> 00:03:53,880
for my username iafzal in /etc/password,

67
00:03:54,180 --> 00:03:56,015
I could do the same thing grep iafzal

68
00:03:56,015 --> 00:03:59,190
/etc/password and it will go into that file

69
00:03:59,190 --> 00:04:02,250
and search for that specific keyword. And it

70
00:04:02,250 --> 00:04:05,190
brings back one line because there is only one

71
00:04:05,220 --> 00:04:09,680
user in /etc/passwd that has the word iafzal,

72
00:04:09,680 --> 00:04:12,450
and that's me, of course, right. Next

73
00:04:12,450 --> 00:04:16,920
command or the next syntax that we'll learn is

74
00:04:16,920 --> 00:04:20,579
search, search for a keyword and count it. So if I

75
00:04:20,579 --> 00:04:24,089
am doing, let's hit up arrow key twice, and this is

76
00:04:24,089 --> 00:04:26,459
a command we ran again, which is to grep Seinfeld

77
00:04:26,459 --> 00:04:29,730
from seinfeld-characters, and it gives me two but

78
00:04:29,730 --> 00:04:33,300
what if you have a file that has 1000s of words

79
00:04:33,450 --> 00:04:36,120
that matches your criteria, and you want to know

80
00:04:36,120 --> 00:04:38,430
how many times it shows up, then you could just

81
00:04:38,430 --> 00:04:41,580
simply do grep -c, and it would tell you that

82
00:04:41,610 --> 00:04:46,590
it is showing up two times. So that's what -c

83
00:04:46,620 --> 00:04:50,460
is used for. The next one is -i which is the

84
00:04:50,460 --> 00:04:54,060
one that you should always use and I have a habit

85
00:04:54,180 --> 00:04:57,870
of using grep with always -i. What -i

86
00:04:57,870 --> 00:05:00,330
does is it actually search for keyword and

87
00:05:00,360 --> 00:05:05,130
ignores the case sensitive. Meaning if I have grep

88
00:05:05,130 --> 00:05:08,400
Seinfeld seinfeld-character it gave me 2 Seinfeld.

89
00:05:08,400 --> 00:05:13,290
What if I have, in inside of this while I have a

90
00:05:13,290 --> 00:05:16,560
seinfeld with lowercase s. So let's say if I'm

91
00:05:16,560 --> 00:05:19,740
grepping for seinfeld with lowercase s, then hit

92
00:05:19,740 --> 00:05:22,770
enter. It's not giving me anything, even though I

93
00:05:22,770 --> 00:05:25,680
know there is a word seinfeld in it. So that's

94
00:05:25,680 --> 00:05:29,790
why I always use -i option to tell my system,

95
00:05:29,790 --> 00:05:33,870
hey, ignore any uppercase or lowercase, from that

96
00:05:33,870 --> 00:05:38,007
keyword, and from that file. And you do -i,

97
00:05:38,007 --> 00:05:40,860
it actually greps and gets you the

98
00:05:40,860 --> 00:05:43,620
result, regardless whether they are written in

99
00:05:43,620 --> 00:05:48,240
uppercase or lowercase. Next one is n, displays the

100
00:05:48,240 --> 00:05:52,590
matched line and their line numbers. So we used, let's

101
00:05:52,590 --> 00:05:55,500
clear the screen, and if you remember, use -c

102
00:05:55,500 --> 00:05:59,220
option, which gives you the total number of lines

103
00:05:59,220 --> 00:06:02,190
that matched our criteria. Now I wanted to see

104
00:06:02,190 --> 00:06:04,980
those lines to end the line and number where

105
00:06:05,010 --> 00:06:09,300
exactly it happened. So in that case, I hit up up

106
00:06:09,300 --> 00:06:12,660
arrow key and replace -c with -n, hit

107
00:06:12,660 --> 00:06:15,510
enter. And you will see, it will give me the two

108
00:06:15,510 --> 00:06:18,180
lines that match my criteria. And it also telling

109
00:06:18,180 --> 00:06:21,720
me, the first line is actually on the line number

110
00:06:21,720 --> 00:06:24,720
one, and the second matched line is line number

111
00:06:24,750 --> 00:06:28,410
eight. Isn't that awesome? Yeah, I like it. Okay.

112
00:06:28,650 --> 00:06:31,740
Next one is -v, also very powerful. Meaning

113
00:06:31,740 --> 00:06:37,140
what if you want to get everything but that search

114
00:06:37,320 --> 00:06:40,470
keyword. So let's say if I want to get all the

115
00:06:40,470 --> 00:06:44,550
lines that do not match seinfeld. So let's do

116
00:06:44,550 --> 00:06:51,240
grep -v seinfeld, or I could just do vi or

117
00:06:51,240 --> 00:06:58,920
iv to include, i as in to ignore, seinfeld from

118
00:06:58,920 --> 00:07:02,160
seinfeld-characters. And now you will see I have a

119
00:07:02,160 --> 00:07:05,400
list of every line that the whole file content,

120
00:07:05,640 --> 00:07:10,560
but this does not have that two Jerry Seinfeld, and

121
00:07:10,560 --> 00:07:15,030
Morty Seinfeld. These two lines are omitted

122
00:07:15,300 --> 00:07:19,680
or are excluded from it because I use the -v

123
00:07:19,680 --> 00:07:23,100
option. So -v is basically telling the system

124
00:07:23,280 --> 00:07:27,660
give me everything except this search keyword. All

125
00:07:27,660 --> 00:07:31,470
right. The next one is what if you want to combine

126
00:07:31,470 --> 00:07:34,890
the keyword with other texts processors commands

127
00:07:34,890 --> 00:07:37,200
that we have learned previously. Right. Yes, we

128
00:07:37,200 --> 00:07:40,230
could definitely do that. So let's say if I type

129
00:07:40,530 --> 00:07:44,520
grep seinfeld, or let me run the same command,

130
00:07:44,520 --> 00:07:47,250
the last command, grep -vi seinfeld and

131
00:07:47,250 --> 00:07:51,060
seinfeld-characters, right? Right. So what if I

132
00:07:51,060 --> 00:07:54,240
want to print, from this output I only wanted to

133
00:07:54,240 --> 00:07:56,940
print the first column. Then you could, what you

134
00:07:56,940 --> 00:07:59,400
could do is you could hit up arrow key, pipe it

135
00:07:59,400 --> 00:08:04,230
right here, awk it and dollar by the way, chop

136
00:08:04,230 --> 00:08:07,050
down the line, it is not actually putting into a

137
00:08:07,050 --> 00:08:09,870
new line. It's a continuation of the same line. If

138
00:08:09,870 --> 00:08:11,610
you make your window bigger, you will see it as

139
00:08:11,610 --> 00:08:14,280
coming up in one line. Let me show you real quick.

140
00:08:14,670 --> 00:08:19,050
You see if I do it this, see went back. So print

141
00:08:20,070 --> 00:08:25,890
dollar one, and curly braces, and quote close. And

142
00:08:25,890 --> 00:08:30,270
now it's giving me only the first column off my

143
00:08:30,360 --> 00:08:34,320
matched criteria. Now, what if I wanted to get only

144
00:08:34,320 --> 00:08:38,308
the first three letters have this output? Can you

145
00:08:38,308 --> 00:08:41,370
guess, what could that be? I'm sure you know how to

146
00:08:41,370 --> 00:08:44,610
do it. But if you forgot, that's fine, you hit up

147
00:08:44,610 --> 00:08:48,090
arrow key, now you could put another pipe. And now

148
00:08:48,090 --> 00:08:51,990
that you could do cut -c for characters, and

149
00:08:51,990 --> 00:08:54,870
you want the first three that will be one minus

150
00:08:54,900 --> 00:08:57,120
three, one through three because you are picking

151
00:08:57,120 --> 00:09:00,450
the range. And now you will see it is giving you

152
00:09:00,480 --> 00:09:03,690
everything except the keyword line that matches

153
00:09:03,690 --> 00:09:07,350
Seinfeld. Alright, let's clear the screen. Let me

154
00:09:07,350 --> 00:09:11,580
make my window a little smaller. And I'll move on

155
00:09:11,580 --> 00:09:16,230
to the next one, which is ls -l. So grep does

156
00:09:16,230 --> 00:09:20,670
not only search for a keyword from a file, it

157
00:09:20,670 --> 00:09:24,120
actually search for any keyword from any output of

158
00:09:24,120 --> 00:09:28,920
a command. So let's say if I have, let me go to my

159
00:09:28,920 --> 00:09:32,400
home directory, so it's /home/iafzal/seinfeld.

160
00:09:32,400 --> 00:09:35,640
I'll go one step back to cd .., it will bring me

161
00:09:35,640 --> 00:09:38,820
back to my /home/iafzal directory. Now in

162
00:09:38,820 --> 00:09:41,790
here, when I do ls -l, you're gonna see the

163
00:09:41,790 --> 00:09:44,580
listing of all the files and directories. Now what

164
00:09:44,580 --> 00:09:48,420
in this, what if in this output, I only wanted to

165
00:09:48,420 --> 00:09:52,140
see the line that matched the file or directory

166
00:09:52,140 --> 00:09:56,790
Desktop. So I hit up arrow key, pipe it, and now

167
00:09:56,820 --> 00:10:02,280
I'll grep it for Desktop, and let's say just for

168
00:10:02,850 --> 00:10:06,630
giggles, use the lowercase d, and hit enter and

169
00:10:06,630 --> 00:10:09,360
it's not going to give me anything. Why? Because if

170
00:10:09,360 --> 00:10:12,720
you notice the Desktop has uppercase D, so you

171
00:10:12,720 --> 00:10:15,450
could either do hit up arrow key and replace the

172
00:10:15,480 --> 00:10:18,660
lowercase d with uppercase or leave it

173
00:10:18,660 --> 00:10:22,980
as it, and put -i option to ignore the case

174
00:10:22,980 --> 00:10:25,230
sensitive, hit enter, and you're gonna see that it

175
00:10:25,230 --> 00:10:28,470
is pulling only that line, that matched the word

176
00:10:28,500 --> 00:10:32,610
Desktop. Isn't that cool? All right, now let me go

177
00:10:32,610 --> 00:10:35,520
into the grep and egrep functionality. Now you

178
00:10:35,520 --> 00:10:39,030
know grep works perfectly on every keyword. Now

179
00:10:39,390 --> 00:10:42,570
the egrep comes into play when you want to search

180
00:10:42,630 --> 00:10:47,370
two words from a file. So let's clear the screen,

181
00:10:47,430 --> 00:10:50,580
let's go into the seinfeld directory. In seinfeld

182
00:10:50,580 --> 00:10:53,040
directory, we have a file called seinfeld, and let's

183
00:10:53,040 --> 00:10:56,190
cat that seinfeld-characters file, hit enter.

184
00:10:56,700 --> 00:10:59,610
And you'll see these are the contents of that

185
00:11:00,210 --> 00:11:04,350
file. Now what if I want to get the list or lines

186
00:11:04,350 --> 00:11:07,800
that match not only Seinfeld, but also Costanza.

187
00:11:08,730 --> 00:11:11,580
For that we will use the egrep, which is a little

188
00:11:11,580 --> 00:11:15,180
powerful command than grep. So it will be egrep

189
00:11:15,600 --> 00:11:19,170
-i of course, I want to ignore uppercase or

190
00:11:19,170 --> 00:11:22,690
lowercase, here you put double quote,

191
00:11:22,690 --> 00:11:25,209
[No audio]

192
00:11:25,209 --> 00:11:28,230
the keyword and the first keyword I want to search for is

193
00:11:28,230 --> 00:11:33,000
Seinfeld, then the for the second keyword you have

194
00:11:33,000 --> 00:11:36,360
to put a pipe in the middle and then put the

195
00:11:36,360 --> 00:11:42,060
second keyword would be Costanza, close with the

196
00:11:42,060 --> 00:11:45,120
double quotes, and of course specify the file name

197
00:11:45,120 --> 00:11:49,500
from where you are trying to search. You hit

198
00:11:49,530 --> 00:11:52,650
enter, and now you will see it is picking up, let me

199
00:11:52,650 --> 00:11:55,920
make this bigger so, and hit the up arrow key, so

200
00:11:55,920 --> 00:11:58,500
you know what exactly the output. Now you see it's

201
00:11:58,500 --> 00:12:01,603
giving me Jerry Seinfeld, George Costanza,

202
00:12:01,603 --> 00:12:05,790
Frank Costanza, Estelle Costanza, and Morty Seinfeld. So all

203
00:12:05,790 --> 00:12:09,570
the lines that match Seinfeld and Costanzas are

204
00:12:09,840 --> 00:12:14,790
there. So again, if you wanted to awk it out for

205
00:12:14,790 --> 00:12:18,570
a second column, if you wanted to cut it out for

206
00:12:18,570 --> 00:12:22,140
certain characters, you could definitely do that

207
00:12:22,140 --> 00:12:26,370
by putting pipe after one another. So this

208
00:12:26,370 --> 00:12:29,970
lecture is all about grep and egrep, and again,

209
00:12:30,000 --> 00:12:33,300
I want you to try man on grep and try different

210
00:12:33,330 --> 00:12:36,240
options that are available to you like these are

211
00:12:36,240 --> 00:12:39,660
the different options. Try it if you have time,

212
00:12:39,690 --> 00:12:42,750
otherwise the ones I showed you, these are more

213
00:12:42,750 --> 00:12:45,930
than enough for you to perform your everyday daily

214
00:12:45,930 --> 00:12:47,915
task while you are at the job.

215
00:12:47,915 --> 00:12:50,091
[No audio]