How to read column data from a text file in a bash shell script

One common task in day-to-day shell scripting jobs is to read data line by line from a file, parse the data, and process it. The input file can be either a regular text file (e.g., logs or config files) where each line contains multiple fields separated by space, or a CSV file that is formatted with delimiter-separated values in each row. This bash tutorial describes how to read columns from a file and store them into separate variables for further processing.