(Tcl) Using sudo in an SSH Shell Session

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Demonstrates how to run a command as sudo in a shell session.

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load ./chilkat.dll

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

set ssh [new_CkSsh]

set port 22
set success [CkSsh_Connect $ssh "the-ssh-server.com" $port]
if {$success != 1} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

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

# Start a shell session.
# (The QuickShell method was added in Chilkat v9.5.0.65)
set channelNum [CkSsh_QuickShell $ssh]
if {$channelNum < 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

# Construct a StringBuilder with our command ("ls") run with "sudo"
# Note: The line-endings are potentially important.  Some SSH servers may
# require either LF or CRLF line endings.  (Unix/Linux/OSX servers typically
# use bare-LF line endings.  Windows servers likely use CRLF line endings.)

# Using "sudo -S" causes the sudo prompt to be written to stderr,
# and the password is read from stdin (i.e. from the echo command ouput).
# The sudo commands -p option allows us to set the prompt, and we can set it to
# the empty string, thus eliminating the prompt from the stderr completely.
# This allows us to run the command as root (super-user) with no prompt.
set sbCommands [new_CkStringBuilder]

CkStringBuilder_Append $sbCommands "echo \"theSshPassword\" | sudo -S -p \"\" ls\n"

# Add another command to echo a marker string that
# we'll use in ChannelReceiveUntilMatch below.
# The use of single quotes around 'IS' is a trick so that the output
# of the command is "THIS IS THE END OF THE SCRIPT", but the terminal echo
# includes the single quotes.  This allows us to read until we see the actual
# output of the last command.
CkStringBuilder_Append $sbCommands "echo THIS 'IS' THE END OF THE SCRIPT\n"

# Send the commands..
set success [CkSsh_ChannelSendString $ssh $channelNum [CkStringBuilder_getAsString $sbCommands] "ansi"]
if {$success != 1} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    delete_CkStringBuilder $sbCommands
    exit
}

# Send an EOF to indicate no more commands will be sent.
# For brevity, we're not checking the return values of each method call.
# Your code should check the success/failure of each call.
set success [CkSsh_ChannelSendEof $ssh $channelNum]

# Receive output up to our marker.
set success [CkSsh_ChannelReceiveUntilMatch $ssh $channelNum "THIS IS THE END OF THE SCRIPT" "ansi" 1]

# Close the channel.
# It is important to close the channel only after receiving the desired output.
set success [CkSsh_ChannelSendClose $ssh $channelNum]

# Get any remaining output..
set success [CkSsh_ChannelReceiveToClose $ssh $channelNum]

# Get the complete output for all the commands in the session.
puts "--- output ----"
puts [CkSsh_getReceivedText $ssh $channelNum ansi]

delete_CkSsh $ssh
delete_CkStringBuilder $sbCommands