[Linux] Bash awk uso equivalente: Process text files and extract data

Overview

The awk command is a powerful text processing tool in Unix-like operating systems. It is primarily used for pattern scanning and processing, allowing users to extract and manipulate data from files or input streams based on specified patterns.

Usage

The basic syntax of the awk command is as follows:

awk [options] 'pattern { action }' file

Common Options

• -F: Specifies the field separator (default is whitespace).
• -v: Allows you to assign a value to a variable before executing the program.
• -f: Allows you to specify a file containing awk commands.
• -e: Allows you to specify the awk program as a command line argument.

Common Examples

Example 1: Print specific columns

To print the first and third columns from a file named data.txt, you can use:

awk '{print $1, $3}' data.txt

Example 2: Using a custom field separator

If your data is comma-separated, you can specify the field separator with the -F option:

awk -F, '{print $1, $2}' data.csv

Example 3: Pattern matching

To print lines that contain the word “error” from a log file:

awk '/error/' log.txt

Example 4: Calculating sums

To calculate the sum of values in the second column of a file:

awk '{sum += $2} END {print sum}' data.txt

Example 5: Using variables

You can use the -v option to set a variable and use it in your awk command:

awk -v threshold=100 '$2 > threshold {print $1}' data.txt

Tips

• Always quote your awk commands to avoid shell interpretation issues.
• Use the BEGIN and END blocks to perform actions before processing the input or after finishing it, respectively.
• Test your awk commands with sample data to ensure they work as expected before applying them to larger datasets.