Curly braces and GREP tool

Curly braces allow you to specify a set of characters from which the shell automatically forms all possible combinations

touch file{1,2,3} o/p: Will create 3 files file1,file2,file3
mkdir directory{1,2,3}{a,b,c} o/p: directories created: directory1a,directory1b,etc
touch file{a..z}

The following is the summary of various io-redirection and logical operators
  


Pattern searching using grep

Stands for globally search for the regular expression (RE) and print out the line.

Return status – success 0, pattern not found 1, file not found 2


ps -ef | grep root

The preceding command will show all processes running currently whose user ID is "root"

Metacharacter	Function	Example	Description
^	Beginning-of-line anchor	'^mango'	Will display all lines beginning with mango
$	End-of-line anchor	'mango'$'	Will display all lines ending with mango
.	Matches single character	'm..o'	Will display lines containing m, followed by two characters, followed by an o
*	Matches zero or more characters preceding the asterisk	'*mango'	Will display lines with zero or more spaces, followed by the pattern mango
[ ]	Matches single character in the set	'[Mm]ango'	Will display lines containing Mango or mango
[^]	Matches single character not in the set	'[^A–M] ango'	Will display lines not containing a character in the range A through M, followed by ango
\<	Beginning-of-word anchor	'\<mango'	Will display lines containing a word that begins with mango
\>	End-of-word anchor	'mango\>'	Will display lines containing a word that ends with mango

We will try the following commands on the sample.txt file:

Sr. no.	Command	Description
1	grep Fruit sample.txt	This will show all lines with pattern Fruit.
2	grep Fruit G*	This searches pattern Fruit in all files starting with G.
3	grep '^M' sample.txt	This searches all lines starting with M.
4	grep '6$' sample.txt	This searches lines ending with 6.
5	grep '1\..' sample.txt	This displays lines containing 1 and any character after it.
6	grep '\.6' sample.txt	This shows lines containing .6.
7	grep '^[AT]' sample.txt	This searches lines starting with A or T.
8	grep '[^0-9]' sample.txt	This contains at least one alphabet.
9	grep '[A-Z][A-Z] [A-Z]' sample.txt	This searches the upper case, upper case space, and upper case word.
10	grep '[a-z]\{8\}' sample. txt	This displays all lines in which there are at least eight consecutive lowercase letters.
11	grep '\<Fruit' sample.txt	This displays all lines containing a word starting with Fruit. The \< is the beginning-of-word anchor.
12	grep '\<Fruit\>' sample. txt	This displays the line if it contains the word Fruit. The \< is the beginning-of-word anchor and the \> is the end-of-word anchor.
12	grep '\<[A-Z].*o\>' sample.txt	This displays all lines containing a word starting with an uppercase letter, followed by any number of characters and a word ending in o.
14	grep -n '^south' sample. txt	This displays line numbers also.
15	grep –i 'pat' sample.txt	This displays case insensitive search.
16	grep -v 'Onion' sample.txt > temp mv temp sample.txt	This deletes the line containing pattern.
17	grep –l 'Nuts' *	This lists files containing pattern.
18	grep –c 'Nuts' sample.txt	This prints the number of lines where pattern is present.
19	grep –w 'Nuts' sample.txt	This counts where the whole world pattern is present, not a part of the word.