USAGE:

rexmv -m -r [-f] [items ...]

-m : regexp matching pattern (may include grouping parentheses).

-r : use $1, $2 and so on to reference grouping from the matching pattern.

-f : actually rename the items, instead of just dry running.

-v : show version.

Examples:

Make everything upper case:

rexmv -m '(.*)' -r '\U$1' *

Change extension from .mp4 to .mpeg4:

rexmv -m '.mp4$' -r '.mpeg4' *

Change '1of8' to 'S01E01', '2of8' to 'S01E02' and so on (useful for renaming tv show episodes):

rexmv -m '(\d+)of8' -r 'S01E0$1' *