How to find the last field using ' cut '

In Unix and Linux systems, the cut command is a highly effective text processing tool for extracting columns or fields from text lines. If you need to find the last field of each line, you can use the cut command in combination with delimiters and other commands to achieve this.

For example, suppose you have a file data.txt with the following content:

shell
John:Doe:25
Jane:Smith:30
Emily:Jones:22

Each line in this file contains three fields separated by colons (:). We aim to extract the last field of each line, which corresponds to the age of each person.

Since the cut command does not natively support extracting the last field, we can combine it with rev (a command that reverses strings) to accomplish this. The specific steps are as follows:

1. Use the rev command to reverse each line.
2. Use the cut command to extract the first field (which is the last field in the original line).
3. Apply the rev command again to reverse the result back to its original order.

Here are the specific commands and execution results:

bash
rev data.txt | cut -d':' -f1 | rev

Explanation:

• rev data.txt: Reverses each line in data.txt.
• cut -d':' -f1: Sets the delimiter to colon (:) and extracts the first field (which is the last field in the original line).
• rev: Reverses the extracted field back to its original sequence.

The execution result will be:

shell
25
30
22

This successfully extracts the last field of each line. Although this approach is slightly convoluted, it provides a straightforward and effective solution when the cut command lacks native support for extracting the last field.