rename — Batch-Rename Files with Patterns

rename renames many files at once, making it the big sibling of mv as soon as regular expressions come into play. Be warned – and this is the single most important fact on this page: there are two completely different programs called rename. This page covers the Perl rename (also file-rename or prename, the default on Debian/Ubuntu), which works with Perl expressions such as rename 's/old/new/' *.txt. RHEL, Fedora, and SUSE, by contrast, ship the util-linux rename, which has an incompatible syntax (rename old new *.txt, a plain string replacement with no regex). Check which one you have with rename --version, and always try commands with -n (dry run) first before letting them loose.

Basic Usage

rename 's/<old>/<new>/' <files> — Replace first occurrence of a pattern in filenames.

rename 's/foo/bar/' *.txt

rename 's/<old>/<new>/g' <files> — Replace all occurrences in filenames.

rename 's/-/_/g' *.html

rename -n 's/<old>/<new>/' <files> — Dry run: show what would be renamed without doing it.

rename -n 's/.jpeg/.jpg/' *.jpeg

rename -v 's/<old>/<new>/' <files> — Verbose: show each rename operation.

rename -v 's/IMG_/photo_/' *.jpg

rename -f 's/<old>/<new>/' <files> — Force: overwrite existing files.

rename -f 's/backup_//' *.sql

Case Changes

rename 'y/A-Z/a-z/' <files> — Convert filenames to lowercase.

rename 'y/A-Z/a-z/' *.JPG

rename 'y/a-z/A-Z/' <files> — Convert filenames to uppercase.

rename 'y/a-z/A-Z/' *.txt

rename 's/(\w+)/\L$1/' <files> — Lowercase entire filename using Perl modifiers.

rename 's/(\w+)/\L$1/' *

rename 's/(\w)/\u$1/' <files> — Capitalize first letter of filename.

rename 's/(\w)/\u$1/' *.txt

Extension Changes

rename 's/\.txt$/.md/' <files> — Change file extension from .txt to .md.

rename 's/\.txt$/.md/' *.txt

rename 's/\.jpeg$/.jpg/' <files> — Normalize JPEG extensions.

rename 's/\.jpeg$/.jpg/' *.jpeg

rename 's/$/.bak/' <files> — Add .bak extension to all files.

rename 's/$/.bak/' *.conf

rename 's/\.bak$//' <files> — Remove .bak extension from all files.

rename 's/\.bak$//' *.bak

Numbering & Padding

rename 's/(\d+)/sprintf("%03d",$1)/e' <files> — Zero-pad numbers in filenames to 3 digits.

rename 's/(\d+)/sprintf("%03d",$1)/e' file*.txt

rename -N 1 's/^/sprintf("%03d_",$N++)/e' <files> — Add sequential numbers as prefix.

rename -N 1 's/^/sprintf("%03d_",$N++)/e' *.jpg

rename 's/(\d+)/$1+100/e' <files> — Offset numbers in filenames by 100.

rename 's/(\d+)/$1+100/e' track_*.mp3

Common Patterns

rename 's/ /_/g' <files> — Replace spaces with underscores in filenames.

rename 's/ /_/g' *

rename 's/[^a-zA-Z0-9._-]/_/g' <files> — Sanitize filenames: replace special chars with underscores.

rename 's/[^a-zA-Z0-9._-]/_/g' *

rename 's/(.+)\.(.+)/$2.$1/' <files> — Swap filename and extension.

rename 's/(.+)\.(.+)/$2.$1/' *.txt

rename 's/^(\d{4})(\d{2})(\d{2})/$1-$2-$3/' <files> — Insert dashes in date-formatted filenames.

rename 's/^(\d{4})(\d{2})(\d{2})/$1-$2-$3/' 20260315*.log

rename 's/^/prefix_/' <files> — Add a prefix to all filenames.

rename 's/^/2026_/' *.csv

Conclusion

The Perl rename is the most powerful batch-renaming tool around, because it brings the full expressive power of regular expressions – including case modifiers (\L, \u) and evaluated code via the /e flag for numbering and calculations. The one rule to remember: make sure which rename is installed, because the util-linux rename on RHEL/SUSE does not understand this Perl syntax and may do something entirely different. Run every operation with -n first, review the preview, and only then run it for real – a wrong expression can mangle many files at once. For simple single renames, mv is enough; for more complex logic beyond filenames, reach for a shell loop with mv and sed.