How to Search and Replace in Unix in Multiple Files

How to Search and Replace in Unix Across Multiple Files

Searching and replacing text within multiple files can be essential for developers and system administrators. Using command-line tools is not only efficient but also allows for complex operations with just a few commands.

Understanding the Basics

The two main tools used for text replacement are sed and awk. Each has unique features suited for various scenarios. Sed is particularly adept at streamlining changes across many files.

Using Sed for Search and Replace

Here's a simple way to use sed to perform search and replace:

1. Open your terminal.
2. Use the following command:

sed -i.bak 's/oldtext/newtext/g' .txt

In this command:

• -i.bak will edit the files in place and create a backup with a .bak extension.
• s/oldtext/newtext/g signifies searching for all instances of "oldtext" and replacing them with "newtext" across all .txt files in the directory.

Using Find with Sed

If you want to execute a search and replace operation on files spread in different directories, you can combine find with sed:

find . -name '.txt' -exec sed -i.bak 's/oldtext/newtext/g' {} +

Advanced Replacement Techniques

In more complex situations, you might need to employ regular expressions. Sed handles regular expressions efficiently:

sed -i.bak -E 's/old[^ ]/newtext/g' .txt

This regex will match any occurrence of "old" followed by any non-space characters, aiding in broader searches.

Pro Tips

• Always test your commands on sample files first to avoid unintended changes.
• Utilize version control systems to track changes during replacements.
• Consider restricting operations to specific directories for safer execution.

Common Use Cases

There are various scenarios where you might want to search and replace across multiple files:

1. Updating configuration files with a new API endpoint.
2. Refactoring code by changing variable names consistently across the project.
3. Replacing outdated text in documentation files.

Conclusion

Using tools like sed and combined with find commands allows for efficient search and replacement in Unix across multiple files. This capability is invaluable for developers and system administrators alike, making text management straightforward and effective.

Glossary of Terms

• sed: A stream editor for filtering and transforming text.
• awk: A programming language for pattern scanning and processing.
• regex: A sequence of characters defining a search pattern.

Pro Tips

• Backup important files before performing bulk changes.
• Use verbose flags to see what changes will be made without executing them immediately.
• Learn basic regex patterns for more advanced searches.

Efficiently Edit Text in Multiple Files

Update: 25 Sep 2025