What is Lua ?

Lua is a powerful, efficient, lightweight, embeddable scripting language, 用标准C语言编写并以源代码形式开放， 其设计目的是为了嵌入应用程序中，从而为应用程序提供灵活的扩展和定制功能。 Lua 是巴西里约热内卢天主教大学（Pontifical Catholic University of Rio de Janeiro）里的一个研究小组，由Roberto Ierusalimschy、Waldemar Celes 和 Luiz Henrique de Figueiredo所组成并于1993年开发。

Lua supports procedural programming, object-oriented programming, functional programming, data-driven programming, and data description.

Installation

curl -R -O http://www.lua.org/ftp/lua-5.3.3.tar.gz
tar zxf lua-5.3.3.tar.gz
cd lua-5.3.3
# build Lua
make linux

 test your building


make test


 if ok


$ sudo make install

cd src && mkdir -p /usr/local/bin /usr/local/include /usr/local/lib /usr/local/man/man1 /usr/local/share/lua/5.1 /usr/local/lib/lua/5.1

cd src && install -p -m 0755 lua luac /usr/local/bin

cd src && install -p -m 0644 lua.h luaconf.h lualib.h lauxlib.h …/etc/lua.hpp /usr/local/include

cd src && install -p -m 0644 liblua.a /usr/local/lib

cd doc && install -p -m 0644 lua.1 luac.1 /usr/local/man/man1

$ lua -v

Lua 5.1.5  Copyright © 1994-2012 Lua.org, PUC-Rio

You can also install lua pkg management tool (like python pip, ruby gem):

$ sudo apt-get install luarocks
$ sudo luarocks install luasocket
Installing http://luarocks.org/repositories/rocks/luasocket-3.0rc1-2.src.rock...
Using http://luarocks.org/repositories/rocks/luasocket-3.0rc1-2.src.rock... switching to 'build' mode
Archive:  /tmp/luarocks_luarocks-rock-luasocket-3.0rc1-2-1445/luasocket-3.0rc1-2.src.rock
  inflating: luasocket-3.0rc1-2.rockspec  
 extracting: v3.0-rc1.zip            
Archive:  v3.0-rc1.zip

Note: make xxx, where xxx is your platform name. eg. linux, macosx, freebsd…

Lua Tutorial

Lua Hello World

  1. Interactive mode:
$ lua
Lua 5.1.5  Copyright (C) 1994-2012 Lua.org, PUC-Rio
> print("hello".." world")
hello world
>
  1. Lua scripts:
#!/usr/local/bin/lua

print("Hello"…" World！")


$ ./test.lua

Hello World！


$ lua test.lua

Hello World！

Example: Http Request

#!/usr/bin/env lua
local http=require("socket.http")
local ltn12 = require("ltn12")

local request_body = [[login=admin&password=pass]]

local response_body = {}

local path = "/v1/users"

local url = "http://example.com"

local token = ""


local res, code, response_headers = http.request{

url = string.format("%s/%s", url, path),

method = "GET",

headers =

{

["Content-Type"] = "application/x-www-form-urlencoded";

},

source = ltn12.source.string(request_body),

sink = ltn12.sink.table(response_body),

}


print(res)

print(code)


if type(response_headers) == "table" then

for k, v in pairs(response_headers) do

print(k, v)

end

end


print("Response body:")

if type(response_body) == "table" then

print(table.concat(response_body))

else

print("Not a table:", type(response_body))

end

Note: If for https request, you can use Lua ssl lib. require("ssl.https"). First, install Lua package manager: sudo apt-get install luarocks

Trouble Shooting

If :

# luarocks install luasec OPENSSL_LIBDIR=/usr/lib/x86_64-linux-gnu/
Warning: Failed searching manifest: Failed extracting manifest file
Installing https://raw.githubusercontent.com/rocks-moonscript-org/moonrocks-mirror/master/luasec-0.6-1.rockspec...
Using https://raw.githubusercontent.com/rocks-moonscript-org/moonrocks-mirror/master/luasec-0.6-1.rockspec... switching to 'build' mode

Error: Could not find expected file openssl/ssl.h, or openssl/ssl.h for OPENSSL – you may have to install OPENSSL in your system and/or pass OPENSSL_DIR

or OPENSSL_INCDIR to the luarocks command. Example: luarocks install luasec OPENSSL_DIR=/usr/local

It means to install openssl lib first. To install openssl: $ sudo apt-get install openssl libssl-dev. then, sudo luarocks install luasec OPENSSL_LIBDIR=/usr/lib/x86_64-linux-gnu/ or sudo luarocks install luasec.

Reference

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