SSH Remote Shell with Multiple Commands

See more SSH Examples

Demonstrates running several commands one after another in a single remote shell session, retrieving each command's output separately. No PTY is requested, so each command is followed by an echoed marker that signals where its output ends.

load ./chilkat.dll

set success 0

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

#  Demonstrates running several commands one after another in a single remote shell session,
#  retrieving each command's output separately.
#  
#  No PTY is requested, so the shell runs non-interactively and never prints a command prompt.
#  Because there is no prompt to synchronize on, each command is followed by an "echo" of a
#  unique marker, and the output is read up to that marker.

set ssh [new_CkSsh]

set hostname "ssh.example.com"
set port 22
set success [CkSsh_Connect $ssh $hostname $port]
if {$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
}

#  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

set caseSensitive 1

#  ---- 1st command: change directory ----
set success [CkSsh_ChannelSendString $ssh $channelNum "cd /tmp; echo END_OF_CMD_1\n" "utf-8"]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

set success [CkSsh_ChannelReceiveUntilMatch $ssh $channelNum "END_OF_CMD_1" "utf-8" $caseSensitive]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

#  Retrieving the text also clears the receive buffer, which matters: if the next marker were
#  left in the buffer, the following receive would match immediately.
set cmdOutput [CkSsh_getReceivedText $ssh $channelNum "utf-8"]
if {[CkSsh_get_LastMethodSuccess $ssh] == 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

puts "$cmdOutput"

#  ---- 2nd command: directory listing ----
set success [CkSsh_ChannelSendString $ssh $channelNum "ls; echo END_OF_CMD_2\n" "utf-8"]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

set success [CkSsh_ChannelReceiveUntilMatch $ssh $channelNum "END_OF_CMD_2" "utf-8" $caseSensitive]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

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

puts "$cmdOutput"

#  ---- 3rd command: long listing, then finish the session ----
set success [CkSsh_ChannelSendString $ssh $channelNum "ls -l\n" "utf-8"]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

#  No more input will be sent.
set success [CkSsh_ChannelSendEof $ssh $channelNum]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

set success [CkSsh_ChannelReceiveToClose $ssh $channelNum]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

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

puts "$cmdOutput"

CkSsh_Disconnect $ssh

delete_CkSsh $ssh