Lua

Get Text Received on an SSH Channel

Demonstrates the Chilkat Ssh.GetReceivedText method, which decodes and returns all text currently accumulated in a channel's normal receive buffer. The first argument is the channel number and the second is the charset. The receive buffer is cleared after the text is returned.

Background: This is the retrieval half of the read-then-get pattern: a Channel* read or receive call fills the buffer, and this hands you the text. Because the buffer is cleared on retrieval, each call returns only what arrived since the last one. A valid channel with nothing buffered returns an empty string successfully, so an empty result is not an error. Retrieve text promptly after a channel completes, before other SSH operations can discard the completed channel record.

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Lua

local chilkat = require("chilkat")

-- Demonstrates the Ssh.GetReceivedText method, which decodes and returns all text currently in
-- a channel's normal receive buffer.  The 1st argument is the channel number and the 2nd is the
-- charset.  The receive buffer is cleared after the text is returned.

local ssh = chilkat.Ssh.new()

local sshPort = 22
local success = ssh:connect("ssh.example.com", sshPort)
if not success then
    print(ssh.last_error_text)
    return
end

-- Normally you would not hard-code the password in source.  You should instead obtain it
-- from an interactive prompt, environment variable, or a secrets vault.
local password = "mySshPassword"

success = ssh:authenticate_pw("mySshLogin", password)
if not success then
    print(ssh.last_error_text)
    return
end

local channelNum = ssh:open_session_channel()
if channelNum < 0 then
    print(ssh.last_error_text)
    return
end

success = ssh:send_req_exec(channelNum, "cat /etc/hostname")
if not success then
    print(ssh.last_error_text)
    return
end

-- IMPORTANT: Set a read timeout.  ReadTimeoutMs defaults to 0, which means no limit -- without
-- it, this call waits forever if the server never sends channel close.
ssh.read_timeout_ms = 15000

success = ssh:channel_receive_to_close(channelNum)
if not success then
    print(ssh.last_error_text)
    return
end

-- Retrieve the accumulated output.  A valid channel with no buffered data returns an empty
-- string successfully.
local output = ssh:get_received_text(channelNum, "utf-8")
if not ssh.last_method_success then
    print(ssh.last_error_text)
    return
end

print(output)

ssh:disconnect()