How to Replace Words in FILE1 with Corresponding Values from FILE2 Using AWK in Linux?

Summary: Learn how to effectively use `AWK` to replace words in `FILE1` with corresponding values from `FILE2` in a Linux environment.
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How to Replace Words in FILE1 with Corresponding Values from FILE2 Using AWK in Linux?

If you work regularly in the Linux environment, you're likely well-versed in shell scripting and command-line tools. One powerful tool that often comes in handy is AWK. In this guide, we will discuss an efficient way to replace words in FILE1 with corresponding values from FILE2 using AWK.

Understanding AWK

AWK is a versatile programming language designed for text processing and typically used as a data extraction and reporting tool. Its associative arrays and ability to handle complex pattern-matching tasks make it especially useful for file manipulation tasks.

Scenario

Imagine you have two files: FILE1 and FILE2.

FILE1 contains text where certain words need to be replaced.

FILE2 contains pairs of words where each line has a word to search for and its replacement.

For example:
FILE1:

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FILE2:

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Our goal is to substitute each word in FILE1, according to pairs in FILE2 using AWK.

The AWK Command

Here is a step-by-step process to achieve this:

Step 1: Prepare the AWK Script

Combine the two files so that you can use AWK to look up replacements:

[[See Video to Reveal this Text or Code Snippet]]

Let’s break down this AWK command:

NR==FNR{a[$1]=$2; next}: As we process FILE2, store the replacement pairs into an associative array a.

NR refers to the total record number.

FNR is the record number in the current file.

a[$1]=$2 assigns the value $2 to the key $1 in the array a.

next skips to the next line, keeping the script focused on FILE2.

{for (i=1;i<=NF;i++) if ($i in a) $i=a[$i]}: For each word in FILE1, check if there's a corresponding replacement in array a.

NF is the number of fields in the current record.

if ($i in a) $i=a[$i] means if the word $i exists in the array a, replace it with a[$i].

1: This is a shorthand for { print }, which prints the modified line.

Step 2: Execute the Script

Run the above AWK command in the terminal:

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The output should now display the modified content of FILE1:

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Conclusion

Using AWK for replacing words in one file by referencing corresponding values in another file is both efficient and powerful. This method can be particularly useful in data preprocessing and text manipulation tasks.

Whether you're scripting daily tasks or managing large datasets, mastering tools like AWK expands your capability to perform complex text processing with ease.

Happy coding!