rename.ul

rename expression files

expression
    A Perl expression that modifies the filename. It's typically a substitution command like 's/old/new/' or a more complex sequence of Perl operations using variables and functions. 's/foo/bar/' replaces 'foo' with 'bar', 'y/a-z/A-Z/' convert to upper case. The $_ variable represents the original filename within the Perl code.

files
    A list of files to be renamed. Can include wildcards like * and ?. For example, '*.txt' renames all files with the '.txt' extension.

The rename command, often referred to as rename.ul to differentiate it from other rename utilities, provides a powerful way to rename multiple files based on Perl regular expressions.
It iterates through a list of files, applying the specified Perl expression to each filename. The expression can perform replacements, insertions, deletions, and other string manipulations. This makes it ideal for tasks such as converting filenames to lowercase, removing spaces, adding sequential numbers, or correcting typos across numerous files.
Its strength lies in its flexibility, allowing for complex renaming operations. However, this also means users need a basic understanding of Perl regular expressions to utilize its full potential. Without Perl knowledge, using rename becomes difficult. Backup your data before using it.

Requires a working knowledge of Perl regular expressions. Errors in the expression can lead to unintended and potentially destructive renames.
It renames files directly and does not provide an 'undo' option. ALWAYS backup files before running rename.
The command does not provide confirmation or preview of rename operations.

• To rename all files ending in '.htm' to '.html':
  rename 's/.htm$/.html/' *.htm
• To convert all filenames to lowercase:
  rename 'y/A-Z/a-z/' *
• To remove spaces from filenames:
  rename 's/ //g' *
• To prefix all files with 'new_':
  rename 's/^/new_/' *

rename does not handle errors gracefully. If a rename operation fails (e.g., due to insufficient permissions or a file already existing with the new name), the process may continue with other files, leading to inconsistent results.

The rename command is a common utility found on many Unix-like systems. Different versions of rename exist, but rename.ul generally refers to the Perl-based implementation. It has been part of standard Unix toolsets for a long time, providing a valuable tool for batch file management. Its widespread availability and Perl's popularity have contributed to its continued use.

mv(1), find(1)