Perl

Receive from an SSH Channel Until a Pattern Matches

Demonstrates the Chilkat Ssh.ChannelReceiveUntilMatch method, which receives text until the accumulated text matches a pattern. The arguments are the channel number, the pattern, the charset, and whether matching is case-sensitive. Existing buffered text is checked before waiting for more network data.

Important: Set the ReadTimeoutMs property before calling this method. It defaults to 0, meaning no limit, so without it the call waits forever if the received data never contains a match.

Background: Driving a shell channel means knowing when the remote side has finished talking. With no PTY requested the shell is non-interactive and never prints a prompt, so the reliable signal is a marker you deliberately echo after your command. This method automates "read until you see X." The pattern syntax is deliberately minimal: literal characters plus *, which matches zero or more characters and can span line breaks. ? and bracket classes are not supported, and backslash does not escape a literal *.

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Perl

use chilkat();

$success = 0;

#  Demonstrates the Ssh.ChannelReceiveUntilMatch method, which receives text until the
#  accumulated text matches a pattern.  The 1st argument is the channel number, the 2nd is the
#  pattern, the 3rd is the charset, and the 4th selects case-sensitive matching.  The pattern
#  supports literal characters plus "*", which matches zero or more characters.

$ssh = chilkat::CkSsh->new();

$sshPort = 22;
$success = $ssh->Connect("ssh.example.com",$sshPort);
if ($success == 0) {
    print $ssh->lastErrorText() . "\r\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.
$password = "mySshPassword";

$success = $ssh->AuthenticatePw("mySshLogin",$password);
if ($success == 0) {
    print $ssh->lastErrorText() . "\r\n";
    exit;
}

$channelNum = $ssh->OpenSessionChannel();
if ($channelNum < 0) {
    print $ssh->lastErrorText() . "\r\n";
    exit;
}

#  Start a shell WITHOUT requesting a PTY.  Without a PTY the shell sees it is connected to a
#  raw data pipe and enters non-interactive mode: it suppresses the command prompt, does not
#  echo typed commands back, and skips interactive login scripts.  The output is therefore
#  clean and easily parseable -- but because no prompt is ever sent, code must not wait for
#  one.  Instead, have each command print a predictable marker, or wait for EOF / channel close.
$success = $ssh->SendReqShell($channelNum);
if ($success == 0) {
    print $ssh->lastErrorText() . "\r\n";
    exit;
}

#  There is no prompt to wait for, so make the command itself announce when it has finished
#  by echoing a marker after it.
$success = $ssh->ChannelSendString($channelNum,"ls -l /tmp; echo DONE_MARKER\n","utf-8");
if ($success == 0) {
    print $ssh->lastErrorText() . "\r\n";
    exit;
}

#  IMPORTANT: Set a read timeout before receiving until a match.  ReadTimeoutMs defaults to 0,
#  which means no limit -- without it, this call waits forever if the received data never
#  contains a match.
$ssh->put_ReadTimeoutMs(15000);

#  Receive until the marker appears in the output.
$caseSensitive = 0;
$success = $ssh->ChannelReceiveUntilMatch($channelNum,"DONE_MARKER","utf-8",$caseSensitive);
if ($success == 0) {
    print $ssh->lastErrorText() . "\r\n";
    exit;
}

$output = $ssh->getReceivedText($channelNum,"utf-8");
if ($ssh->get_LastMethodSuccess() == 0) {
    print $ssh->lastErrorText() . "\r\n";
    exit;
}

print $output . "\r\n";

$ssh->Disconnect();