How to use the command repren (with examples)

Repren is a multi-pattern string replacement and file renaming tool. It is a command-line tool that allows users to easily rename files and perform find-and-replace operations on file contents using either literal strings or regular expressions.

Use case 1: Do a dry-run renaming a directory of PNGs with a literal string replacement

Code:

repren --dry-run --rename --literal --from 'find_string' --to 'replacement_string' *.png

Motivation: The motivation for this example is to demonstrate how to perform a dry-run of renaming files in a directory. By using the --dry-run flag, the command will display the changes that would be made without actually renaming any files. This can be useful to preview the effects of the rename operation before committing to it.

Explanation:

• --dry-run: This flag indicates that the operation should be performed as a dry-run, meaning that no actual changes will be made.
• --rename: This flag specifies that the operation being performed is a rename operation.
• --literal: This flag indicates that the replacement string provided is a literal string.
• --from 'find_string': This argument specifies the string that should be found and replaced in the filenames.
• --to 'replacement_string': This argument specifies the string that should be used as the replacement.

Example output: Dry-run output:

Renaming file1.png to filereplacement_string.png
Renaming file2.png to filereplacement_string.png
Renaming file3.png to filereplacement_string.png

Use case 2: Do a dry-run renaming a directory of JPEGs with a regular expression

Code:

repren --rename --dry-run --from 'regular_expression' --to 'replacement_string' *.jpg *.jpeg

Motivation: The motivation for this example is to demonstrate how to perform a dry-run renaming operation using a regular expression pattern as the search criteria. Regular expressions provide a powerful way to search for patterns in filenames, allowing for more complex and flexible renaming operations.

Explanation:

• --rename: This flag specifies that the operation being performed is a rename operation.
• --dry-run: This flag indicates that the operation should be performed as a dry-run, meaning that no actual changes will be made.
• --from 'regular_expression': This argument specifies the regular expression pattern that should be used to search for filenames to be renamed.
• --to 'replacement_string': This argument specifies the replacement string that should be used for the filenames.

Example output: Dry-run output:

Renaming file1.jpg to filereplacement_string.jpg
Renaming file2.jpeg to filereplacement_string.jpeg
Renaming file3.jpeg to filereplacement_string.jpeg

Use case 3: Do a find-and-replace on the contents of a directory of CSV files

Code:

repren --from '([0-9]+) example_string' --to 'replacement_string \1' *.csv

Motivation: The motivation for this example is to demonstrate how to perform a find-and-replace operation on the contents of files in a directory. This can be useful for making bulk changes to file contents, such as updating a specific string pattern.

Explanation:

• --from '([0-9]+) example_string': This argument specifies the regular expression pattern to search for within the file contents. The pattern is designed to match a sequence of digits followed by the string “example_string”.
• --to 'replacement_string \1': This argument specifies the replacement string to be used. The “\1” in the replacement string refers to the matched sequence of digits in the search pattern.

Example output: File content changes:

Before:
This is an example string: 123 example_string

After:
This is an example string: replacement_string 123

Use case 4: Do both a find-and-replace and a rename operation at the same time, using a pattern file

Code:

repren --patterns path/to/patfile.ext --full *.txt

Motivation: The motivation for this example is to demonstrate how to perform both a find-and-replace and a rename operation simultaneously by using a pattern file. This can be useful when multiple search patterns and replacements need to be applied to different files.

Explanation:

• --patterns path/to/patfile.ext: This argument specifies the path to a pattern file that contains the search and replacement patterns. The pattern file allows for specifying multiple search and replacement pairs.
• --full: This flag specifies that the command should perform both the find-and-replace and the rename operation.

Example output: File name changes:

Renaming file1.txt to filereplacement_string1.txt
Renaming file2.txt to filereplacement_string2.txt
Renaming file3.txt to filereplacement_string3.txt

Use case 5: Do a case-insensitive rename

Code:

repren --rename --insensitive --patterns path/to/patfile.ext *

Motivation: The motivation for this example is to demonstrate how to perform a case-insensitive rename operation. By using the --insensitive flag, the command will match filenames regardless of their case, allowing for a more flexible renaming operation.

Explanation:

• --rename: This flag specifies that the operation being performed is a rename operation.
• --insensitive: This flag indicates that the command should perform a case-insensitive match when searching for filenames.
• --patterns path/to/patfile.ext: This argument specifies the path to a pattern file that contains the search and replacement patterns.

Example output: File name changes:

Renaming File1.txt to filereplacement_string1.txt
Renaming FILE2.txt to filereplacement_string2.txt
Renaming fiLe3.txt to filereplacement_string3.txt

Conclusion:

In this article, we explored several use cases of the repren command, a powerful tool for multi-pattern string replacement and file renaming. We looked at examples of renaming files with literal string replacement, performing find-and-replace operations on file contents, combining find-and-replace and rename operations using a pattern file, and performing case-insensitive renames. These examples highlight the versatility and flexibility of the repren command in performing various file renaming tasks.