awk

Definition

A domain-specific programming language designed specifically for text processing and data extraction, particularly excellent at handling data formatted in columns.

Explain Like I'm New

The command-line spreadsheet. If you have a file with rows and columns separated by spaces, `awk` can easily say 'Print only the 3rd column, but only if the 1st column is greater than 50'.

Real World Example

You run the `df -h` command to see hard drive space. It outputs 6 columns. You only want the column showing the percentage full. You pipe it: `df -h | awk '{print $5}'`. It strips away everything else and just prints the 5th column.

Common Use Cases

•Data extraction
•Log parsing
•Reporting

Interview Questions

basic

In `awk`, how do you refer to the very first column of text in a row?

intermediate

If a CSV file is separated by commas instead of spaces, how do you tell `awk` to process it correctly?

Flash Cards

Question

First column?

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Answer

Using `$1`.

Question

Process commas?

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Answer

You use the Field Separator flag (`-F`). Example: `awk -F ',' '{print $2}' file.csv`.