[examples/rename] Add mass file rename example.

examples/rename.lua

@@ -0,0 +1,42 @@
+#!/bin/env lua
+-- Basic mass file renamer using osx and
+-- standard Lua gsub().
+--
+-- Renames every file inside a directory.
+-- A trimmed down but functional and useful
+-- variant of util-linux rename(1) 
+--
+-- Author Lorenzo Cogotti, The DoubleFourteen Code Forge
+
+local io = require 'io'
+local osx = require 'osx'
+local write = io.write
+local dir = osx.dir
+local sep = osx.sep
+
+local ENOENT = 2  -- errno value for No such file or directory
+
+-- Read command line arguments
+local pattern = assert(select(1, ...), "Missing filename pattern argument")
+local repl = assert(select(2, ...), "Missing filename replacement argument")
+local path = select(3, ...) or "."
+
+for filename in dir(path) do
+    local newfilename = filename:gsub(pattern, repl, 1)
+
+    if filename ~= newfilename then
+        local from = path..sep..filename
+        local to = path..sep..newfilename
+
+        local buf, err, code = osx.stat(to)
+        if buf then
+            error(filename..": File '"..to.."' exists, refusing to overwrite.")
+        end
+        if code ~= ENOENT then
+            error(err)
+        end
+
+        write(from, ' -> ', to)
+        assert(osx.rename(filename, newfilename))
+    end
+end