Perl

Multiple SendReqExec on the Same Connection

Demonstrates running a series of commands on one SSH connection using SendReqExec. Each exec request requires its own logical channel — this is not a separate SSH connection, just a new session channel on the existing one.

Background: An SSH session channel is single-use for an exec request: once the command runs and the server closes the channel, that channel cannot be reused. Opening a fresh channel per command is cheap, since the expensive work — the TCP connection, key exchange, and authentication — is done once and shared. This is why running ten commands over one connection is far faster than connecting ten times.

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use strict;
use warnings;
use Chilkat2;

# This example requires the Chilkat API to have been previously unlocked.
# See Global Unlock Sample for sample code.

# Demonstrates running a series of commands on one SSH connection using SendReqExec.  Each exec
# request requires its own logical channel.  This is not a new SSH connection -- it is simply a
# new session channel on the existing one.

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

my $hostname = 'ssh.example.com';
my $port = 22;
my $success = $ssh->Connect($hostname, $port);
if (!$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;
}

# 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);

# ---- 1st command, on its own session channel ----
my $channelNum = $ssh->OpenSessionChannel();
if ($channelNum < 0) {
    print $ssh->LastErrorText, "\n";
    exit;
}

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

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

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

print $cmdOutput, "\n";
print "----\n";

# ---- 2nd command, on a NEW session channel over the same connection ----
$channelNum = $ssh->OpenSessionChannel();
if ($channelNum < 0) {
    print $ssh->LastErrorText, "\n";
    exit;
}

$success = $ssh->SendReqExec($channelNum, 'nslookup chilkatsoft.com');
if (!$success) {
    print $ssh->LastErrorText, "\n";
    exit;
}

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

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

print $cmdOutput, "\n";

$ssh->Disconnect();