enter code hereI have a C++ application running on an Embedded Linux device which uses systemd.
If I wish to stream the debug output of my services / processes, I SSH into the device and execute command journalctl -u <my_systemd_service>.service -f from the terminal, where <my_systemd_service> is my actual service name.
Now the issue is that during production, I'd like to have SSH disabled for security reasons. However, I would still like to be retrieve the debug output sometimes, triggered by sending an MQTT command to the device as the device is connected to an MQTT broker.
Is there a way to get my debug output from within the C++ code itself when the MQTT command is received?
I don't suppose using system() would be ideal. For example system("journalctl -u <my_systemd_service>.service -f") ? Of course this would also need to run in a separate thread if so. Any recommendations would be appreciated.
You can direct service stdout/stderr to a file then read it using std::fstream whenever you need. You might want to see this: https://stackoverflow.com/a/43830129/11277878
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I am developing the test suit in C++ for the PDA-like device running Linux.
While working with development kit I have access to a serial console with system output. Eventually my software should be used on closed box with no console output and Ethernet connection available. I would like to be able to duplicate the entire console output (not only my code output, that would be easy). Any suggestions?
The SSH to the device is working, but apparently it only echoes the commands and responses I send from the remote console. I would like to sniff in on all system output from previously started applications and kernel.
I am trying to get some scripts to run upon an aws termination action. I have created /etc/init.d/Script.sh and linked symbolically to /etc/rc01.d/K01Script.sh
However terminating through aws console did not produce the output I was looking for. (It is a script that does a quick API call to a server over https should take only a few seconds).
Then I tried again but specifically changed a kernel parameter:
'sudo sysctl -w kernel.poweroff_cmd=/etc/rc0.d/K01Script.sh'
and again no output.
I get the message "The system is going down for power off NOW!" when terminating the server so I'm pretty sure the Ubuntu server is going into runlevel 0. Permissions are owned by root.
I know I could create a lifecycle to do something like this but my team prefers the quick and dirty way.
any help very much appreciated!
I have a scheduling program running on Server A running Windows 2008 RS. Server B is my SAS server under Windows 2008 R2. How do I kick-off a job on SAS server from my scheduling server? I can either use the sas.exe or a batch file to start my job. Owners of the SAS server tell me that I cannot add an application or Windows service to the SAS server. Is this even possible?
Below is a copy of my answer to a slightly different question (source: http://www.runsubmit.com/questions/260/hide-sas-batch-jobs-winxp). I'm copy/pasting it here for perpetuity and also because it's more likely to help people searching:
You can use PsExec which is part of Microsoft/Sysinternals list of utility programs. This file will go on the scheduling server. Grab it from here:
http://technet.microsoft.com/en-us/sysinternals/bb897553.aspx
The tool is designed to allow you to execute jobs on remote machines. For example, if you want to launch a SAS program from the command line you could run:
psexec \\machinename sas.exe -sysin remotedrivename:\remotefolder\myprogram.sas
This would launch SAS.EXE on the remote machine and run the supplied program that exists on the remote machine. When it launches SAS it appears to launch it within a PsServ service. Because it's running within a service no interface will be displayed. I'm not even sure if you would see it appear as it's own process or application in windows task manager. If you use SysInternals other program, ProcessExplorer, instead of Task Manager you can see this happening.
Note that the REMOTE MACHINE and the LOCAL machine can be the same machine.
PROS: Many other uses for this technique. It's free. PsExec is only required on the machine that is making the call, not both machines.
CONS: Its a bit of a roundabout way to do things. Need to install a third party program (although it is now a MS tool). Some antivirus programs/network admins may not allow it.
Note that if your SAS jobs access network resources then you will probably need to make the network resource available first using the net map command. I suggest running your sas job in a batch file like so (or use the 'x' command from within your SAS file to call the 'net use' commands):
Command executed from local machine:
psexec \\machinename -sysin remotedrivename:\remotefolder\myprogram.BAT
Contents of batch file on remote machine:
net use m: \\fileserver\sharedfolder /USER:mynetworkdomainname\myusername mypassword
sas.exe -sysin remotedrivename:\remotefolder\myprogram.sas
net use m: /delete
I want to run Linux command remotely from Window based Qt C++ application programmatically. What is the simpliest way to do it?
You need some sort of server on the Linux machine and your Windows machine will be a client. I'd say the easiest way would be just make a php script to run your command and drop it in your www root and have your Windows machine fetch that URL.
At the end of the day, without knowing what your requirements are with regard to security and with regard to what kind of commands you'll be running is, it's very difficult to give a definitive answer to this question.
Simply connect to telnet server on the linux using sockets, and send the commands.
This actually requires very little code. Check the Java version here:
Sending telnet commands and reading the response with Java
You can do similarly with Qt/C++ as well.
Simple server-side program witch will handle the requests and then using ex system() function will be this "remotely" part of solution.
And on client-side simple text field handled by function witch will be able to connect to server to send command run request.
The most important thing in this solution will be to take care about security.
One way to do it is, to have a client-server model, the server resides in linux and client can be your computer. That way you can send commands to the server and have its output thrown at you. That's one way I think of this problem.
Use UPnP to get past the firewall(or use NAT traversal or UDP/TCP hole punching). Otherwise (without forwarding the port) it would be impossible to reach the server.
The second is to write your own RSH and SSH utility. (or use putty or other pre-existing software)
You could use Plink if you are on Windows whatever version. If you can run PuTTY, then you can run PLink. PuTTY Plink Documentation. Using that you could use the executable, and automate things. Otherwise, if you're looking for a specific programming language, they'd still be dependent upon some SSH Library. If you're writing your own installer, you could include the PLink.exe in your installer, and distribute it with your application.
From the documentation page:
Z:\sysosd>plink login.example.com 'echo "Hello World"'
I am wondering if someone can provide me with a couple c++ functions that would allow me to send and receive data over a telnet port.
I've also heard that I can create a program, and have it run via SSH, this would be preferred just because of the security benefits of SSH, are there any samples out there?
Update:
What I want to do, is create a console program users could use remotely via SSH or telnet. I am a C++ programmer.
Update 2: I know I was vague, I am creating an inventory system that I want to be accessible to our employees via SSH or telnet. I will be using sockets, and will often display data to the user via (telnet or through ssh) and accept input from them. I will have to implement sockets, and send data and receive data I know, is there a library for this?
I am not quite sure what you are asking here.
You can execute a remote program via:
ssh <user>#<machine> "<command>"
(Provided you have prepared a passphrase-less pubkey authentication; you'd be asked for a password / passphrase otherwise. The very first invokation will also require user input as SSH wants to verify the fingerprint of the remote machine.)
You could then capture the output of that command line (which is equivalent to the output of the remote command, unless ssh itself belches an error) via the usual means.
I seriously dont believe you want to implement telnet and SSH protocol all by your handwritten code!! That would be too difficult for you.
What I think you want to do is to "Run a command remotely". is it?
If yes then you you would need to execute the command as told by DevSolar but you will need to generate SSH keygen to be installed so that it doesnt ask for password at the prompt.
Else write an expect script.