‘Sed’ command #4 – HackerRank Solution

In this post, we will solve ‘Sed’ command #4 HackerRank Solution. This problem (‘Sed’ command) is a part of Linux Shell series.

Objective

Sed is a popular utility that enables quick parsing and transformation of text. Here are some basic uses for it:

Substitute the first occurrence of editor with tool:

$:~/hackerrank/bash/grep/grep1$ echo "My favorite programming editor is Emacs. Another editor I like is Vim." | sed -e s/editor/tool/
My favorite programming tool is Emacs. Another editor I like is Vim.

Substitute all occurrences of editor with tool:

$:~/hackerrank/bash/grep/grep1$ echo "My favorite programming editor is Emacs. Another editor I like is Vim." | sed -e s/editor/tool/g
My favorite programming tool is Emacs. Another tool I like is Vim.  

Substitute the second occurrence of editor with tool:

$:~/hackerrank/bash/grep/grep1$ echo "My favorite programming editor is Emacs. Another editor I like is Vim." | sed -e s/editor/tool/2
My favorite programming editor is Emacs. Another tool I like is Vim.

Highlight all occurrences of editor by enclosing them in curly brackets (i.e., {}):

$:~/hackerrank/bash/grep/grep1$ echo "My favorite programming editor is Emacs. Another editor I like is Vim." | sed -e s/editor/{\&}/g
My favorite programming {editor} is Emacs. Another {editor} I like is Vim.

Task

Given n lines of credit card numbers, mask the first 12 digits of each credit card number with an asterisk (i.e., *) and print the masked card number on a new line. Each credit card number consists of four space-separated groups of four digits. For example, the credit card number 1234 5678 9101 1234 would be masked and printed as **** **** **** 1234.

Input Format

Each line contains a credit card number in the form dddd dddd dddd dddd, where d denotes a decimal digit (i.e., 0 through 9). There are a total of n lines of credit card numbers.

Constraints

• 1 <= n <= 20; note that the value of n does not matter when writing your command.

Output Format

For each credit card number, print its masked version on a new line.

Sample Input

1234 5678 9101 1234  
2999 5178 9101 2234  
9999 5628 9201 1232  
8888 3678 9101 1232  

Sample Output

**** **** **** 1234
**** **** **** 2234
**** **** **** 1232
**** **** **** 1232

Explanation

Observe that the first twelve digits have been masked for each credit card number, and they are printed in the same order as they were received as input.

Solution – ‘Sed’ command #4 – HackerRank Solution

sed -r 's/[0-9]{4}[ ]/**** /g'

Note: This problem (‘Sed’ command #4) is generated by HackerRank but the solution is provided by CodingBroz. This tutorial is only for Educational and Learning purpose.