Demonstrating practical applications

Here, I’m using various variables and arrays that were introduced in previous chapters. Let’s put this into practice with the following Bash script:

Figure 4.11 – Introducing BASH_REMATCH in a practical application

This example code can be found in the ch04_regex_02.sh file in this chapter’s folder. In this script, I declared the user_list variable on line 3. On line 6, I declared the pattern variable. On line 8, I started a while loop that reads each line of data from the $user_list variable.

On line 9, I used the match operator, =~, to compare each line ($line) against our regex pattern ($pattern). These are referred to by the $line and $pattern variables, which are declared. When you use the match operator, the string on the left (represented by the $line variable) is matched against the regex pattern on the right. If the pattern matches, the expression returns true (0); otherwise,...