Open WhatsApp from the shell with Termux

open-whatsapp

#!/data/data/com.termux/files/usr/bin/env lua

-- Escape a string for use in a shell command
local function shell_escape(args)
  local ret = {}
  local s
  for _, a in pairs(args) do
    s = tostring(a)
    if s:match("[^A-Za-z0-9_/:=-]") then
      s = "'" .. s:gsub("'", "'\\''") .. "'"
    end
    table.insert(ret, s)
  end
  return table.concat(ret, " ")
end

-- Convert a character to its hex representation
local char_to_hex = function(c)
  return string.format("%%%02X", string.byte(c))
end

-- URL encode a string
local function urlencode(url)
  if url == nil then
    return
  end
  url = url:gsub("\n", "\r\n")
  url = url:gsub("([^%w ])", char_to_hex)
  url = url:gsub(" ", "+")
  return url
end

-- Get the phone number and message from the arguments
local phone = arg[1]
local message = arg[2]

-- The phone number is required
if phone == nil then
  print("Usage: open-whatsapp <phone> [message]")
  os.exit(1)
else
  -- Strip any non-digit characters from the phone number
  phone = phone:gsub("%D", "")
end

-- Generate a wa.me link (with the message if it exists)
local link = "https://wa.me/" .. phone
if message ~= nil then
  link = link .. "?text=" .. urlencode(message)
end

-- Open the link
os.execute("( " .. shell_escape({ "termux-open-url", link }) .. " >/dev/null 2>&1 & )")