Rename multiple files based on pattern in Unix

Question

There are multiple files in a directory that begin with prefix fgh, for example:

fghfilea
fghfileb
fghfilec

I want to rename a

Answer 1

It was much easier (on my Mac) to do this in Ruby. Here are 2 examples:

# for your fgh example. renames all files from "fgh..." to "jkl..."
files = Dir['fgh*']

files.each do |f|
  f2 = f.gsub('fgh', 'jkl')
  system("mv #{f} #{f2}")
end

# renames all files in directory from "021roman.rb" to "021_roman.rb"
files = Dir['*rb'].select {|f| f =~ /^[0-9]{3}[a-zA-Z]+/}

files.each do |f|
  f1 = f.clone
  f2 = f.insert(3, '_')
  system("mv #{f1} #{f2}")
end