Objective-C

Multiple SendReqExec on the Same Connection

Demonstrates running a series of commands on one SSH connection using SendReqExec. Each exec request requires its own logical channel — this is not a separate SSH connection, just a new session channel on the existing one.

Background: An SSH session channel is single-use for an exec request: once the command runs and the server closes the channel, that channel cannot be reused. Opening a fresh channel per command is cheap, since the expensive work — the TCP connection, key exchange, and authentication — is done once and shared. This is why running ten commands over one connection is far faster than connecting ten times.

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Objective-C

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

BOOL success = NO;

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

//  Demonstrates running a series of commands on one SSH connection using SendReqExec.  Each exec
//  request requires its own logical channel.  This is not a new SSH connection -- it is simply a
//  new session channel on the existing one.

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

NSString *hostname = @"ssh.example.com";
int port = 22;
success = [ssh Connect: hostname port: [NSNumber numberWithInt: port]];
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;
}

//  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];

//  ---- 1st command, on its own session channel ----
int channelNum = [[ssh OpenSessionChannel] intValue];
if (channelNum < 0) {
    NSLog(@"%@",ssh.LastErrorText);
    return;
}

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

success = [ssh ChannelReceiveToClose: [NSNumber numberWithInt: channelNum]];
if (success == NO) {
    NSLog(@"%@",ssh.LastErrorText);
    return;
}

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

NSLog(@"%@",cmdOutput);
NSLog(@"%@",@"----");

//  ---- 2nd command, on a NEW session channel over the same connection ----
channelNum = [[ssh OpenSessionChannel] intValue];
if (channelNum < 0) {
    NSLog(@"%@",ssh.LastErrorText);
    return;
}

success = [ssh SendReqExec: [NSNumber numberWithInt: channelNum] command: @"nslookup chilkatsoft.com"];
if (success == NO) {
    NSLog(@"%@",ssh.LastErrorText);
    return;
}

success = [ssh ChannelReceiveToClose: [NSNumber numberWithInt: channelNum]];
if (success == NO) {
    NSLog(@"%@",ssh.LastErrorText);
    return;
}

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

NSLog(@"%@",cmdOutput);

[ssh Disconnect];