Add-On REGEX

Question 1

Show an example of the following anchors?

• Beginning of a string
• End of a string
• Word boundary

Answer 1

‘^SearchString’
‘SearchString$’
‘\bSearchString\b’

Question 2

What are character classes for:
any lowercase letter
any uppercase letter
any letter
hexadecimal values

Answer 2

[[:lower:]]
[[:upper:]]
[[:alpha:]]
[[:alnum:]]

Question 3

Regex example to check if only one char was entered?

Answer 3

’^[[:alpha:]]$’

Question 4

Write a pattern that matches any word that begins with b, followed by a vowel, and ending with t.

Answer 4

\bb[aeiou]t\b

Question 5

Match any digit or carat symbol

Match line that does not contain numbers

Match any line containing a digit

Match any line containing a minus, zero or nine

Answer 5

[0-9^]

[^0-9]

[0-9]

[-09]

Question 6

What are the special character classes for:
[0-9] (digits)
[\t\r\n] (whitespaces)
[A-Za-z0-9_]

Answer 6

[[:digit:]]
[[:space:]]
[[:alnum:]]

Question 7

Regex should check only one of the following words item0, item1….

Answer 7

^item[[:digit:]]$

Question 8

Find any three character?

Answer 8

‘\b[[:alnum:]]\b’

Question 9

Find any line that contains only one character?

Answer 9

’^[[:alnum:]]$’

Question 10

Match any word that contains three lowercase letters?

Answer 10

‘\b[[:lower:]]{3}\b’

Question 11

5 ‘a’ characters
5 or more ‘a’ characters
between 5 and 7 ‘a’ characters
between 3 and 5 lowercase characters

Answer 11

a{5}
a{5,}
a{5,7}
[[:lower:]]{3,5}

Question 12

What is the shorthand version of:
a{0,} - zero ore more
a{1,} - one or more
a{0,1} - zero or one

Answer 12

a*
a+
a?

Question 13

Find any number, whether it’s a whole number or a decimal

Answer 13

’[[:digit:]]+.?[[:digit:]]*’

Question 14

Search for dog or cat or fish

Answer 14

dog|cat|fish

Question 15

Search for cat or bat?

Answer 15

cat|bat

[cb]at

Question 16

Search for:
hack, crack, hacking, hacked, cracking, cracked

Answer 16

(hack|crack)(ing|ed)?

Question 17

egrep command to search for IP address?

Answer 17

egrep ‘^([[:digit:]]{1,3}.){3}[[:digit:]]{1,3}$’ testgr.txt

Question 18

egrep command that matches either 202-224-1228 or (202)224-1228?

Answer 18

egrep ‘(([[:digit:]]{3}))|([[:digit]]{3}-)[[:digit:]]{3}-[[:digit]]{4}’ testgr.txt

Question 19

egrep command that matches either “color” or “colour”?

Answer 19

egrep ‘colo[u]?r’ testgr.txt

Question 20

How can I do the following:

1. Reverse grep
2. Case insensitive
3. show a byte offset in the input file to the match
4. show only the match
5. Color the exact match

Answer 20

1. grep -v
2. grep -i
3. grep -b
4. grep -o
5. grep –color