> ## Documentation Index > Fetch the complete documentation index at: https://notes.kodekloud.com/llms.txt > Use this file to discover all available pages before exploring further. # Introduction to awk > Awk is a powerful language for text processing, enabling easy filtering, transforming, and formatting of structured text. Awk is a powerful, domain-specific language for text processing. Whether you’re automating seat lookups in a movie theater or parsing system statistics, Awk’s field-oriented syntax and built-in variables make it easy to filter, transform, and format structured text. ## Why Use Awk? * Processes structured data by rows (records) and columns (fields) * Handles irregular whitespace automatically * Integrates seamlessly into Unix pipelines * Offers concise one-liners or full-fledged scripts ## Fields and Records Imagine a seating chart stored in `minimovies.txt`, where “Y” means a seat is taken and “N” means it’s available. Awk treats each line as a **record** and each whitespace-separated item as a **field**. ![The image is an "Introduction to awk" diagram showing a table with columns labeled 1 to 5 and rows containing letters "a" to "e" with "y" and "n" indicating whether something is taken or not. A legend explains that "y" means it's taken and "n" means it's not.](https://kodekloud.com/kk-media/image/upload/v1752868662/notes-assets/images/Advanced-Bash-Scripting-Introduction-to-awk/introduction-to-awk-diagram.jpg) * Columns ➔ Fields (`$1`, `$2`, …) * Rows ➔ Records (`NR` is the built-in record counter) ### Extracting a Specific Seat Step 1: Select the third column (`$3`) for every record.\ Step 2: Filter for record number 2 using `NR`. ![The image is an introduction to the "awk" command, showing a table with columns labeled a, b, c, d, e, and highlighting column c. It includes instructions for using "awk" to extract column c and create a comparison operation for equality.](https://kodekloud.com/kk-media/image/upload/v1752868663/notes-assets/images/Advanced-Bash-Scripting-Introduction-to-awk/awk-command-introduction-column-c.jpg) ```bash theme={null} # Verify Awk installation $ awk --version # Step 1: Print the 3rd field for each line $ awk '{ print $3 }' minimovies.txt c n n n y # Step 2: Only line 2 $ awk 'NR == 2 { print $3 }' minimovies.txt n ``` `NR` is a built-in Awk variable representing the current record (line) number.\ Fields are referenced as `$1`, `$2`, etc. ## Awk as a Domain-Specific Language Awk is more than a simple filter—it’s a small programming language tailored for text. It provides: * Pattern-action statements * Built-in variables (`NR`, `NF`, `FS`, `OFS`) * Control structures (`if`, `while`, `for`) ![The image is a slide titled "Introduction to awk," explaining that a Domain-Specific Language is a programming language designed for a specific subject area.](https://kodekloud.com/kk-media/image/upload/v1752868664/notes-assets/images/Advanced-Bash-Scripting-Introduction-to-awk/introduction-to-awk-dsl-slide.jpg) Awk treats any sequence of spaces and tabs as the default field separator (`FS` = `[ \t]+`). ## Handling Irregular Spacing Even if your data has inconsistent spacing, Awk splits fields correctly: ![The image is an introduction to "awk," highlighting its ability to create powerful programs or one-liner scripts for parsing large and complex text data easily.](https://kodekloud.com/kk-media/image/upload/v1752868665/notes-assets/images/Advanced-Bash-Scripting-Introduction-to-awk/awk-introduction-text-parsing.jpg) ```bash theme={null} $ awk 'NR == 2 { print $3 }' minimovies.txt n ``` ## Integrating Awk with Unix Pipelines Combine Awk with other commands to filter and format on the fly: ```bash theme={null} $ cat minimovies.txt | awk '$1 == "2" { print $4 }' n ``` ### Common Use Cases | Command | Purpose | Example | | ------- | -------------------- | ---------------------------------------- | | top | System runtime stats | `top \| awk '{ print $2 }' \| head -5` | | ps | Process listing | `ps aux \| awk '$3 > 50 {print $1, $3}'` | | df -h | Disk usage report | `df -h \| awk '$5 > "80%"'` | ```bash theme={null} $ top | awk '{ print $2 }' | head -n 5 702 Avg: 996838 353T 41224173/79G ``` ```bash theme={null} $ df -h Filesystem Size Used Avail Use% Mounted on C:/Program Files/Git 459G 182G 277G 40% / G: 15G 0 15G 0% /g ``` ## Writing Full Awk Scripts Instead of one-liners, you can write complete Awk programs: ```awk theme={null} #!/usr/bin/awk -f BEGIN { print "Hello, World!" } ``` Make it executable and run directly: ```bash theme={null} $ chmod +x hello.awk $ ./hello.awk Hello, World! ``` Ensure the shebang path (`/usr/bin/awk`) matches your system’s Awk installation. Awk transforms text processing into an intuitive workflow by combining pattern matching, field manipulation, and a minimal scripting language. Whether you need quick one-liners or full scripts, Awk has you covered. ## Links and References * [GNU Awk User’s Guide](https://www.gnu.org/software/gawk/manual/gawk.html) * [Kubernetes Basics](https://kubernetes.io/docs/concepts/overview/what-is-kubernetes/) * [Docker Hub](https://hub.docker.com/) * [Terraform Registry](https://registry.terraform.io/)