Template for (small) command line scripts written in lua (5.2)

cli.lua

#! /usr/bin/env lua

local function main(argv)
  local name =  argv[1] or 'World'
  sh.spawn('echo "Hello, %s!"', name)
end


---
-- I/O helper functions
---

_G.sh = {}
function sh.q(str)
  if str == nil then
    return
  end

	return string.gsub(str, "'", [['"'"']])
end

function sh.qt(str)
  if str == nil then
    return
  end

  return sh.q(str:sub(1, #str - 1))
end

function sh.trim(str)
  return str:match('^%s*(.*%S)') or ''
end

function sh.run(cmd, ...)
  local command = cmd:format(...)
  local p = io.popen(command, 'r') or {}
  local output = p:read('*a')
  local _, _, status = p:close()

  if status ~= 0 then
    error(string.format("Failed to execute '%s'", command))
    return
  end

  return output
end

function sh.get(...)
  return sh.qt(sh.run(...))
end

function sh.spawn(cmd, ...)
  os.execute(cmd:format(...))
end

function sh.read(msg, ...)
  io.write(msg:format(...))
  return io.read()
end

function sh.confirm(cmd)
  local input = sh.read('%s\nConfirm (y/n): ', cmd)
  if input == 'y' then
    sh.spawn(cmd)
  end
end

main(_G.arg)