Lua

Send EOF on an SSH Channel

Demonstrates the Chilkat Ssh.ChannelSendEof method, which sends an SSH EOF message on a channel. The only argument is the channel number. EOF closes only the client-to-server direction; the application may still receive stdout, stderr, exit status, EOF, and CLOSE from the server.

Background: Many remote commands read standard input until it ends — wc, sort, cat and friends. Sending EOF is the SSH equivalent of pressing Ctrl+D: it tells the remote process no more input is coming so it can finish and emit results. After sending EOF, do not send more data on that channel; a later send may return true even though nothing is delivered.

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Lua

local chilkat = require("chilkat")

-- Demonstrates the Ssh.ChannelSendEof method, which sends an SSH EOF message on a channel.  The
-- only argument is the channel number.  EOF closes only the client-to-server direction; output
-- may still be received from the server.

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, "wc -l")
if not success then
    print(ssh.last_error_text)
    return
end

-- Send input to the remote command.
success = ssh:channel_send_string(channelNum, "line one\nline two\nline three\n", "utf-8")
if not success then
    print(ssh.last_error_text)
    return
end

-- Signal that no more input will be sent.  Do not send more data on this channel afterward.
success = ssh:channel_send_eof(channelNum)
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

-- Output can still be received after EOF is sent.
success = ssh:channel_receive_to_close(channelNum)
if not success then
    print(ssh.last_error_text)
    return
end

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()