Command Execution

Execute external commands and shell scripts with full control over I/O streams.

For executor configuration, see Executor.

Loading

local exec = require("exec")

Acquiring an Executor

Get a process executor resource by ID:

local executor, err = exec.get("app:exec")
if err then
    return nil, err
end

-- Use executor
local proc = executor:exec("ls -la")
-- ...

-- Release when done
executor:release()

Returns: Executor, error

Creating a Process

Create a new process with the specified command:

-- Simple command
local proc, err = executor:exec("echo 'Hello, World!'")

-- With working directory
local proc = executor:exec("npm install", {
    work_dir = "/app/project"
})

-- With environment variables
local proc = executor:exec("python script.py", {
    work_dir = "/scripts",
    env = {
        PYTHONPATH = "/app/lib",
        DEBUG = "true",
        API_KEY = api_key
    }
})

-- Run shell script
local proc = executor:exec("./deploy.sh production", {
    work_dir = "/app/scripts",
    env = {
        DEPLOY_ENV = "production"
    }
})

Returns: Process, error

start / wait

Start the process and wait for completion.

local proc = executor:exec("./build.sh")

local ok, err = proc:start()
if err then
    return nil, err
end

local exit_code, err = proc:wait()
if err then
    return nil, err
end

if exit_code ~= 0 then
    return nil, errors.new("INTERNAL", "Build failed with exit code: " .. exit_code)
end

stdout_stream / stderr_stream

Get streams to read process output.

local proc = executor:exec("./process-data.sh")

local stdout = proc:stdout_stream()
local stderr = proc:stderr_stream()

proc:start()

-- Read all stdout
local output = {}
while true do
    local chunk = stdout:read(4096)
    if not chunk then break end
    table.insert(output, chunk)
end
local result = table.concat(output)

-- Check for errors
local err_output = {}
while true do
    local chunk = stderr:read(4096)
    if not chunk then break end
    table.insert(err_output, chunk)
end

local exit_code = proc:wait()

stdout:close()
stderr:close()

if exit_code ~= 0 then
    return nil, errors.new("INTERNAL", table.concat(err_output))
end

return result

write_stdin

Write data to process stdin.

-- Pipe data to command
local proc = executor:exec("sort")
local stdout = proc:stdout_stream()

proc:start()

-- Write input
proc:write_stdin("banana\napple\ncherry\n")
proc:write_stdin("")  -- Signal EOF

-- Read sorted output
local sorted = stdout:read()
print(sorted)  -- "apple\nbanana\ncherry\n"

proc:wait()
stdout:close()

signal / close

Send signals or close the process.

local proc = executor:exec("./long-running-server.sh")
proc:start()

-- ... later, need to stop it ...

-- Graceful shutdown (SIGTERM)
proc:close()

-- Or force kill (SIGKILL)
proc:close(true)

-- Or send specific signal
local SIGINT = 2
proc:signal(SIGINT)

Permissions

Exec operations are subject to security policy evaluation.

Errors

See Error Handling for working with errors.