$ frs --help

USAGE:
  frs [FLAGS] <search-pattern> <replace-pattern> [base-path]

FLAGS:
  -i, --case-insensetive
  -c, --continue-on-error
  -d, --directory            Rename all matching directories. If no type is set, then everything will be renamed
  -n, --dry-run              This is the default and lets you run it without the actual operation
  -f, --file                 Rename all matching files. If no type is set, then everything will be renamed
  -h, --help                 Prints help information
  -r, --run                  Actually running the rename operation. If you want to set this as default, set the
                            environment variable `FRS_DEFAULT_OP` to `RUN`
  -s, --symlink              Rename all matching symlinks. If no type is set, then everything will be renamed
  -T, --traverse-tree        TODO
  -V, --version              Prints version information
  -v, --verbose              Set the verbosity. In a dry-run its automatically set to 1

ARGS:
  <search-pattern>
  <replace-pattern>
  <base-path>           [default: .]

$ frs -f '([a-z]+)_(\d+)(\..+)' '${2}_${1}${3}' test_folder
test_folder/bar_02.png -> test_folder/02_bar.png
test_folder/foo_01.txt -> test_folder/01_foo.txt

$ cargo +nightly install frs