Tcl

SSH Remote Shell

See more SSH Examples

Demonstrates how to start a shell on a remote SSH server, run a command, and retrieve the output. Tcl

load ./chilkat.dll

set success 0

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

set ssh [new_CkSsh]

# Hostname may be an IP address or hostname:
set hostname "www.some-ssh-server.com"
set port 22

# Connect to an SSH server:
set success [CkSsh_Connect $ssh $hostname $port]
if {$success != 1} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

# Wait a max of 5 seconds when reading responses..
CkSsh_put_IdleTimeoutMs $ssh 5000

# Authenticate using login/password:
set success [CkSsh_AuthenticatePw $ssh "myLogin" "myPassword"]
if {$success != 1} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

# Open a session channel.  (It is possible to have multiple
# session channels open simultaneously.)

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

# Some SSH servers require a pseudo-terminal
# If so, include the call to SendReqPty.  If not, then 
# comment out the call to SendReqPty.
# Note: The 2nd argument of SendReqPty is the terminal type,
# which should be something like "xterm", "vt100", "dumb", etc.
# A "dumb" terminal is one that cannot process escape sequences.
# Smart terminals, such as "xterm", "vt100", etc. process
# escape sequences.  If you select a type of smart terminal,
# your application will receive these escape sequences
# included in the command's output.  Use "dumb" if you do not
# want to receive escape sequences.  (Assuming your SSH
# server recognizes "dumb" as a standard dumb terminal.)
set termType "dumb"
set widthInChars 120
set heightInChars 40
# Use 0 for pixWidth and pixHeight when the dimensions
# are set in number-of-chars.
set pixWidth 0
set pixHeight 0
set success [CkSsh_SendReqPty $ssh $channelNum $termType $widthInChars $heightInChars $pixWidth $pixHeight]
if {$success != 1} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

# Start a shell on the channel:
set success [CkSsh_SendReqShell $ssh $channelNum]
if {$success != 1} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

# Start a command in the remote shell.  This example
# will send a "ls" command to retrieve the directory listing.
set success [CkSsh_ChannelSendString $ssh $channelNum "ls\r\n" "ansi"]
if {$success != 1} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

# Send an EOF.  This tells the server that no more data will 
# be sent on this channel.  The channel remains open, and
# the SSH client may still receive output on this channel.
set success [CkSsh_ChannelSendEof $ssh $channelNum]
if {$success != 1} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

# Read whatever output may already be available on the
# SSH connection.  ChannelReadAndPoll returns the number of bytes
# that are available in the channel's internal buffer that
# are ready to be "picked up" by calling GetReceivedText
# or GetReceivedData.
# A return value of -1 indicates failure.
# A return value of -2 indicates a failure via timeout.

# The ChannelReadAndPoll method waits
# for data to arrive on the connection usingi the IdleTimeoutMs
# property setting.  Once the first data arrives, it continues
# reading but instead uses the pollTimeoutMs passed in the 2nd argument:
# A return value of -2 indicates a timeout where no data is received.

set pollTimeoutMs 2000
set n [CkSsh_ChannelReadAndPoll $ssh $channelNum $pollTimeoutMs]
if {$n < 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

# Close the channel:
set success [CkSsh_ChannelSendClose $ssh $channelNum]
if {$success != 1} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

# Perhaps we did not receive all of the commands output.
# To make sure,  call ChannelReceiveToClose to accumulate any remaining
# output until the server's corresponding "channel close" is received.
set success [CkSsh_ChannelReceiveToClose $ssh $channelNum]
if {$success != 1} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

# Let's pickup the accumulated output of the command:
set cmdOutput [CkSsh_getReceivedText $ssh $channelNum "ansi"]
if {[CkSsh_get_LastMethodSuccess $ssh] != 1} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

# Display the remote shell's command output:
puts "$cmdOutput"

# Disconnect
CkSsh_Disconnect $ssh

delete_CkSsh $ssh