Perl

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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Chilkat2 Perl

use strict;
use warnings;
use Chilkat2;

# 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.

my $ssh = Chilkat2::Ssh->new;

my $sshPort = 22;
my $success = $ssh->Connect('ssh.example.com', $sshPort);
if (!$success) {
    print $ssh->LastErrorText, "\n";
    exit;
}

# 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.
my $password = 'mySshPassword';

$success = $ssh->AuthenticatePw('mySshLogin', $password);
if (!$success) {
    print $ssh->LastErrorText, "\n";
    exit;
}

my $channelNum = $ssh->OpenSessionChannel();
if ($channelNum < 0) {
    print $ssh->LastErrorText, "\n";
    exit;
}

$success = $ssh->SendReqExec($channelNum, 'wc -l');
if (!$success) {
    print $ssh->LastErrorText, "\n";
    exit;
}

# Send input to the remote command.
$success = $ssh->ChannelSendString($channelNum, "line one\nline two\nline three\n", 'utf-8');
if (!$success) {
    print $ssh->LastErrorText, "\n";
    exit;
}

# Signal that no more input will be sent.  Do not send more data on this channel afterward.
$success = $ssh->ChannelSendEof($channelNum);
if (!$success) {
    print $ssh->LastErrorText, "\n";
    exit;
}

# 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->ReadTimeoutMs(15000);

# Output can still be received after EOF is sent.
$success = $ssh->ChannelReceiveToClose($channelNum);
if (!$success) {
    print $ssh->LastErrorText, "\n";
    exit;
}

my $output = $ssh->GetReceivedText($channelNum, 'utf-8');
if (!$ssh->LastMethodSuccess) {
    print $ssh->LastErrorText, "\n";
    exit;
}

print $output, "\n";

$ssh->Disconnect();