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In this tutroial, we will demonstrate how to use the resty command-line utility shipped with OpenResty.

cd ~
export PATH=/usr/local/openresty/bin:$PATH
which resty

screenshot 1

It’s usually in this path.

We can check its version number with the -V option.

resty -V

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If you install OpenResty using our pre-built binary packages for Linux, then you should install the openresty-resty package.

dnf list installed openresty-resty

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Because it’s not in the openresty main package.

It’s much easier to do “hello world” using a resty command, for example.

resty -e 'print("Hello World")'

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Note the -e option.

Or run a Lua script on the terminal.

echo 'print("Hello World")' > hello.lua
cat hello.lua
resty hello.lua

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So it is also a great way to write new command-line applications using OpenResty.

Nonblocking I/O is also possible here.

time resty -e 'ngx.sleep(1) ngx.say("done")'

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Let’s connect to’s 443 port using the cosocket API.

resty -e 'local sock = ngx.socket.tcp() print(sock:connect("", 443))'

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Or using light threads.

resty -e 'ngx.thread.wait(ngx.thread.spawn(function () print("in thread!") end))'

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You can also use Lua modules easily. Let’s create a test module.

mkdir lua/
vim lua/test.lua

The lua/test.lua file looks like this:

local _M = {}

function _M.hello() print("Hello") end

return _M

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And then we use the -I option to add the lua/ directory to the Lua module search paths.

resty -I lua/ -e 'require "test".hello()'

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Without the -I option, it won’t find it.

resty -e 'require "test".hello()'

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This is because the lua/ directory is not in the Lua module search paths by default.

Standard Lua modules can be loaded directly, like

resty -e 'local ok, stdout = require "".run([[echo ok]]) print(stdout)'

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This module is for running abitrary shell commands nonblockingly.

We can also define lua shared memory dictionaries via the --shdict option.

resty --shdict 'dogs 10m' -e 'print(ngx.shared.dogs:set("age", 11))'

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Multiple shared dictionaries can be defined this way.

resty --shdict 'dogs 7m' --shdict 'cats 5m' -e 'print(ngx.shared.dogs, " ", ngx.shared.cats)'

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It can also be handy to inject custom nginx configuration snippets.

resty --http-conf 'lua_regex_match_limit 102400;' -e 'print "ok"'

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We can also play with LuaJIT’s JIT compiler.

Let’s create a hot Lua script.

echo 'local a = 0 for i = 1, 1e8 do a = a + 1 end print(a)' > bench.lua
cat bench.lua

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And then disable the JIT compiler altogether.

time resty -joff bench.lua

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For comparison, we can check how much faster when we enable the JIT compiler.

time resty bench.lua

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Or we can check the compiled Lua code paths, or “traces”, with the -jv option.

resty -jv bench.lua

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Or with even more details like the compiled bytecode dump, IR code dump, as well as machine code dump.

resty -jdump bench.lua

You can always find all the supported features via the -h option.

resty -h

Or refer to its documentation via the restydoc utility.

restydoc resty-cli

If you install openresty through our pre-built binary packages, then you should install the openresty-doc or openresty-restydoc package.

dnf list installed openresty-doc

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We will have a closer look at the restydoc utility in another dedicated video tutorial.

About The Author

Yichun Zhang (Github handle: agentzh), is the original creator of the OpenResty® open-source project and the CEO of OpenResty Inc..

Yichun is one of the earliest advocates and leaders of “open-source technology”. He worked at many internationally renowned tech companies, such as Cloudflare, Yahoo!. He is a pioneer of “edge computing”, “dynamic tracing” and “machine coding”, with over 22 years of programming and 16 years of open source experience. Yichun is well-known in the open-source space as the project leader of OpenResty®, adopted by more than 40 million global website domains.

OpenResty Inc., the enterprise software start-up founded by Yichun in 2017, has customers from some of the biggest companies in the world. Its flagship product, OpenResty XRay, is a non-invasive profiling and troubleshooting tool that significantly enhances and utilizes dynamic tracing technology. And its OpenResty Edge product is a powerful distributed traffic management and private CDN software product.

As an avid open-source contributor, Yichun has contributed more than a million lines of code to numerous open-source projects, including Linux kernel, Nginx, LuaJIT, GDB, SystemTap, LLVM, Perl, etc. He has also authored more than 60 open-source software libraries.