(Objective-C) 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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#import <CkoSsh.h>
#import <CkoStringBuilder.h>

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

CkoSsh *ssh = [[CkoSsh alloc] init];

int port = 22;
BOOL success = [ssh Connect: @"the-ssh-server.com" port: [NSNumber numberWithInt: port]];
if (success != YES) {
    NSLog(@"%@",ssh.LastErrorText);
    return;
}

// Authenticate using login/password:
success = [ssh AuthenticatePw: @"theSshLogin" password: @"theSshPassword"];
if (success != YES) {
    NSLog(@"%@",ssh.LastErrorText);
    return;
}

// Start a shell session.
// (The QuickShell method was added in Chilkat v9.5.0.65)
int channelNum = [[ssh QuickShell] intValue];
if (channelNum < 0) {
    NSLog(@"%@",ssh.LastErrorText);
    return;
}

// 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.
CkoStringBuilder *sbCommands = [[CkoStringBuilder alloc] init];
[sbCommands Append: @"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.
[sbCommands Append: @"echo THIS 'IS' THE END OF THE SCRIPT\n"];

// Send the commands..
success = [ssh ChannelSendString: [NSNumber numberWithInt: channelNum] strData: [sbCommands GetAsString] charset: @"ansi"];
if (success != YES) {
    NSLog(@"%@",ssh.LastErrorText);
    return;
}

// 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.
success = [ssh ChannelSendEof: [NSNumber numberWithInt: channelNum]];

// Receive output up to our marker.
success = [ssh ChannelReceiveUntilMatch: [NSNumber numberWithInt: channelNum] matchPattern: @"THIS IS THE END OF THE SCRIPT" charset: @"ansi" caseSensitive: YES];

// Close the channel.
// It is important to close the channel only after receiving the desired output.
success = [ssh ChannelSendClose: [NSNumber numberWithInt: channelNum]];

// Get any remaining output..
success = [ssh ChannelReceiveToClose: [NSNumber numberWithInt: channelNum]];

// Get the complete output for all the commands in the session.
NSLog(@"%@",@"--- output ----");
NSLog(@"%@",[ssh GetReceivedText: [NSNumber numberWithInt: channelNum] charset: @"ansi"]);