Introduction

The rename utility is a powerful command-line tool available on many Linux distributions for performing batch file renaming using Perl regular expressions or simple string substitutions. Whether you need to standardize filenames, apply sequential numbering, change extensions en masse, or normalize case, rename offers a concise, scriptable solution far more flexible than invoking mv repeatedly.

Versions and Compatibility

There are two primary implementations of rename in widespread use:

• Perl-based rename (sometimes called prename): uses full Perl regular expressions. Common on Debian, Ubuntu and related systems.
• util-linux rename: offers simpler syntax (rename from to files…) and is default on distributions such as Fedora, CentOS and Arch.

Check your version with:

rename --version

For detailed options, consult the rename man page.

Basic Syntax

Using Regular Expressions

The Perl-based variant supports the full spectrum of Perl regex:

• Character classes: [0-9], [A-Za-z]
• Grouping amp alternation: (foobar)
• Quantifiers: , , , {n,m}
• Lookarounds: (=pattern), (!pattern)

Example: prepend IMG_ only to JPEG files:

rename s/^(.).jpeg/IMG_1.jpg/i .JPG

Common Use Cases

1. Changing File Extensions

rename s/.html/.php/ .html

2. Sequential Numbering

Use shell expansion or combine with ls:

a=1 for f in .txt do mv f file_((a  )).txt done

Or with renameutils batch editor: renameutils homepage.

3. Case Conversion

• Lowercase all filenames:
  rename y/A-Z/a-z/
• Uppercase all filenames:
  rename y/a-z/A-Z/

4. Prefix/Suffix Addition

rename s/^/backup_/ .conf

Advanced Techniques

Dry-Run / Preview

Preview changes before applying:

rename -n s/old/new/ 

The -n flag shows proposed renames without executing them.

Combining with find

Recursively rename across directories:

find . -type f -name .log -exec rename s/.log/.txt/ {} 

Undoing with Version Control

If files are tracked in git, you can:

git mv oldname newname

Then commit to maintain history. For bulk renames, use a for loop with git mv.

Troubleshooting and Tips

• Back up critical files before mass renaming.
• Use -n (dry-run) to prevent mistakes.
• Beware of filename collisions: two originals mapping to same target.
• Escape special characters: space, brackets, ampersand.
• When in doubt, wrap filenames in quotes: file.

Alternative Tools

• mmv: moves/copies/links multiple files by wildcard patterns.
• renameutils: interactive editing of rename commands. See renameutils homepage.
• Thunar Bulk Rename: graphical interface for GTK desktops.

Real-World Examples

Renaming Photo Archives

rename s/^DSC0([0-9] )/photo_1/ DSC.JPG

Standardizing Log Files

rename s/^server_log_([0-9]{4})([0-9]{2})([0-9]{2})/1-2-3.log/ server_log_.log

Conclusion

The rename command is an indispensable tool for system administrators, developers, and power users. Its ability to harness regular expressions for batch processing can save hours of manual work. By mastering syntax, leveraging dry-runs, and combining with other utilities like find, you’ll streamline file management workflows with confidence and precision.

Further reading: consult the Perl Regular Expressions tutorial and your distribution’s package documentation for advanced flags.