Receive from an SSH Channel Until a Pattern Matches

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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.

load ./chilkat.dll

set 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.

set ssh [new_CkSsh]

set sshPort 22
set success [CkSsh_Connect $ssh "ssh.example.com" $sshPort]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    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.
set password "mySshPassword"

set success [CkSsh_AuthenticatePw $ssh "mySshLogin" $password]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

set channelNum [CkSsh_OpenSessionChannel $ssh]
if {$channelNum < 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    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.
set success [CkSsh_SendReqShell $ssh $channelNum]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

#  There is no prompt to wait for, so make the command itself announce when it has finished
#  by echoing a marker after it.
set success [CkSsh_ChannelSendString $ssh $channelNum "ls -l /tmp; echo DONE_MARKER\n" "utf-8"]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    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.
CkSsh_put_ReadTimeoutMs $ssh 15000

#  Receive until the marker appears in the output.
set caseSensitive 0
set success [CkSsh_ChannelReceiveUntilMatch $ssh $channelNum "DONE_MARKER" "utf-8" $caseSensitive]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

set output [CkSsh_getReceivedText $ssh $channelNum "utf-8"]
if {[CkSsh_get_LastMethodSuccess $ssh] == 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

puts "$output"

CkSsh_Disconnect $ssh

delete_CkSsh $ssh