Objective-C

Receive an SSH Channel Until Close

Demonstrates the Chilkat Ssh.ChannelReceiveToClose method, which receives data on a channel until the server sends and Chilkat processes channel CLOSE. The only argument is the channel number. EOF alone does not complete this method.

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 server never sends channel close.

Background: This is the simplest and most reliable way to collect the complete output of a one-shot exec command, because the server closes the channel when the command finishes. It is not appropriate for an interactive shell, which never closes on its own — use the poll-based methods there instead. Both stdout and stderr are processed, merged or kept separate according to StderrToStdout.

Chilkat Objective-C Downloads

Download Chilkat for Objective-C

Objective-C

#import <CkoSsh.h>
#import <NSString.h>

BOOL success = NO;

//  Demonstrates the Ssh.ChannelReceiveToClose method, which receives data on a channel until the
//  server sends channel CLOSE.  The only argument is the channel number.  EOF alone does not
//  complete this method.

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

int sshPort = 22;
success = [ssh Connect: @"ssh.example.com" port: [NSNumber numberWithInt: sshPort]];
if (success == NO) {
    NSLog(@"%@",ssh.LastErrorText);
    return;
}

//  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.
NSString *password = @"mySshPassword";

success = [ssh AuthenticatePw: @"mySshLogin" password: password];
if (success == NO) {
    NSLog(@"%@",ssh.LastErrorText);
    return;
}

int channelNum = [[ssh OpenSessionChannel] intValue];
if (channelNum < 0) {
    NSLog(@"%@",ssh.LastErrorText);
    return;
}

success = [ssh SendReqExec: [NSNumber numberWithInt: channelNum] command: @"ls -l /tmp"];
if (success == NO) {
    NSLog(@"%@",ssh.LastErrorText);
    return;
}

//  IMPORTANT: Set a read timeout.  ReadTimeoutMs defaults to 0, which means no limit -- without
//  it, this call waits forever if the server never sends channel close.
ssh.ReadTimeoutMs = [NSNumber numberWithInt:15000];

//  Receive everything the command produces, up to and including channel close.
success = [ssh ChannelReceiveToClose: [NSNumber numberWithInt: channelNum]];
if (success == NO) {
    NSLog(@"%@",ssh.LastErrorText);
    return;
}

NSString *output = [ssh GetReceivedText: [NSNumber numberWithInt: channelNum] charset: @"utf-8"];
if (ssh.LastMethodSuccess == NO) {
    NSLog(@"%@",ssh.LastErrorText);
    return;
}

NSLog(@"%@",output);

[ssh Disconnect];