Show the list of available packages

zrshowpkg.lua

--#!/usr/bin/env texlua
-- zrshowpkg.lua
prog_name = "zrshowpkg"
version = "0.2a"
mod_date = "2016/05/17"
verbose = false
show_path = false
do_validate = true
---------------------------------------- preparations
kpse_progname = nil
unpack = unpack or table.unpack
texlua = pcall(function()
  lfs = require "lfs"
  kpse = require "kpse"
end)
---------------------------------------- logging
do
  local concat = table.concat
  function info(...)
    if not verbose then return end
    local t = { prog_name, ... }
    io.stderr:write(concat(t, ": ").."\n")
  end
  function alert(...)
    local t = { prog_name, "warning", ... }
    io.stderr:write(concat(t, ": ").."\n")
  end
  function abort(...)
    verbose = true; info(...)
    os.exit(-1)
  end
  function sure(val, a1, ...)
    if val then return val end
    abort((type(a1) == "number") and ("error("..a1..")") or a1, ...)
  end
end
---------------------------------------- retrieve information
do
  local fnnorm = function(x) return x end
  local pdelim = ':'
  if os.type == "windows" then
    fnnorm, pdelim = string.lower, ';'
  end
  local function valid_path(file, dir)
    if do_validate then
      local kpath = kpse.find_file(file, "tex", true)
      return (fnnorm(kpath) == fnnorm(dir.."/"..file)) and kpath
    else return dir.."/"..file
    end
  end
  function retrieve_info()
    info("inquiring for search path")
    local path = sure(kpse.expand_path("$TEXINPUTS"), "search path is empty")
    path = path:explode(pdelim)
    info("total found "..#path.." directories")
    local pinfo, tc = {}, 0
    for _, dir in ipairs(path) do
      if lfs.isdir(dir) then
        local dc = 0
        for file in lfs.dir(dir) do
          if not pinfo[file] and fnnorm(file):sub(-4) == ".sty" then
            local fpath = valid_path(file, dir)
            if fpath then
              pinfo[file] = fpath; dc = dc + 1
            end
          end
        end
        info("found "..dc.." files in", dir)
        tc = tc + dc
      else alert("not a directory", dir)
      end
    end
    info("total found "..tc.." files")
    return pinfo
  end
end
---------------------------------------- show information
do
  function show_info(pinfo)
    local lines = {}
    for file, path in pairs(pinfo) do
      local name = file:sub(1, -5)
      local line = (show_path) and name.. " ("..path..")" or name
      table.insert(lines, line)
    end
    table.sort(lines)
    for _, line in ipairs(lines) do
      print(line)
    end
  end
end
---------------------------------------- main
do
  local function show_usage()
    io.stdout:write(([[
This is %s v%s <%s> by 'ZR'
Usage: %s[.lua] [<option>...] [<prog_name>]
Options:
  -p       also show path
  -q       skip validation
  -v       be verbose
]]):format(prog_name, version, mod_date, prog_name))
    os.exit(0)
  end
  function read_option()
    local idx = 1
    while idx <= #arg do
      local opt = arg[idx]
      if opt:sub(1, 1) ~= "-" then break end
      if opt == "-h" or opt == "--help" then
        show_usage()
      elseif opt == "-v" then
        verbose = true
      elseif opt == "-p" then
        show_path = true
      elseif opt == "-q" then
        do_validate = false
      else
        abort("invalid option", opt)
      end
      idx = idx + 1
    end
    if arg[idx] then
      kpse_progname = arg[idx]; idx = idx + 1
    end
    sure(not arg[idx], "wrong number of arguments")
  end
  function main()
    sure(texlua, "this script requrires TeXlua")
    read_option()
    kpse.set_program_name("luatex", kpse_progname)
    show_info(retrieve_info())
  end
end
---------------------------------------- go
main()
-- EOF

Note:
This script must be run with TeXlua (that is, LuaTeX as Lua interpreter). You cannot run it with ordinary Lua binaries.

Usage example:

texlua zrshowpkg.lua latex

Prints the names of all the packages that can be loaded in latex execution.

texlua zrshowpkg.lua -p lualatex

Prints the names of all the packages that can be loaded in lualatex execution, with their locations.