# repren > Multi-pattern string replacement and file renaming tool. > More information: . - Do a dry-run renaming a directory of PNGs with a literal string replacement: `repren {{[-n|--dry-run]}} --rename --literal --from '{{find_string}}' --to '{{replacement_string}}' {{*.png}}` - Do a dry-run renaming a directory of JPEGs with a `regex`: `repren --rename {{[-n|--dry-run]}} --from '{{regex}}' --to '{{replacement_string}}' {{*.jpg}} {{*.jpeg}}` - Do a find-and-replace on the contents of a directory of CSV files: `repren --from '{{([0-9]+) example_string}}' --to '{{replacement_string \1}}' {{*.csv}}` - Do both a find-and-replace and a rename operation at the same time, using a pattern file: `repren {{[-p|--patterns]}} {{path/to/patfile.ext}} --full {{*.txt}}` - Do a case-insensitive rename: `repren --rename {{[-i|--insensitive]}} {{[-p|--patterns]}} {{path/to/patfile.ext}} *`