regular expression based file renamer
rer is a tool that rename files that matches given pattern. Each file name given as argument is matched against pattern. If a match is found file is renamed according to given replacement using PCRE regular expression.
rer /pattern/replacement/modifiers file [file [...]]
rename foobar to foobaz
$ rer /bar/baz/ foobar
Swap first word with second, renaming foo-bar to bar-foo, foo-baz to baz-foo and foo-123 to 123-foo
$ rer '/(\w+)-(\w+)/\2-\1/' foo-bar foo-baz foo-123