my old father is using ubuntu-gnome. He has no static ip address. In order to perform remote administration, I need to know his ip. I was using dyndns free account (configuration in the adsl modem), but this will stop working in a couple of days.
I would like to run a script each time he logs in to publish his ip on my website. I have tried to put a script on the boot, but the network is not available. It seems that it is gnome 3 that starts the network, but I do not know much about gnome 3.
How should I do to have my script run automatically as soon as the network is available ?
One possible non-elegant solution for this is to put your script in his cron to run every X minutes :)
Looking to mine /etc/NetworkManager/ looks like there is a folder dispatcher.d that I think it'll do what you want. Just experiment with a bash/perl/python w/e script in there set the permission appropriately. You can find the UUID in the system-connections/ folder. More information is available in man networkmanager.
EDIT: Look what I found: https://askubuntu.com/questions/13963/call-script-after-connecting-to-a-wireless-network. Seems like this is exactly what you want.
The easiest way is to use another dynamic DNS service. I used to use my own. You could also put curl or wget command to cron or create a systemd service that will call that command periodically. As a target you would have to use your machine with a web server where you can see the IP in your logs.
It is not Gnome that connects the network, it is a system service called NetworkManager. It tries to connect at boot if possible. In some cases it waits for wireless signal, in other cases it waits for a user password. I recently verified that in Fedora, NetworkManager properly implements the systemd's network-online.target but it may have yet to be fixed in other distributions, see the upstream bug report.
https://bugzilla.gnome.org/show_bug.cgi?id=728965
If you want to run a system service just after boot, you need to use:
[Unit]
...
Wants=network-online.target
After=network-online.target
You could also just run a script that calls nm-online at the beginning to wait for the network connectivity if you can expect the connectivity to come up in reasonable time, otherwise it times out. Such a script can be run from any environment including a user session.
And, as noted already, you can put a script into /etc/NetworkManager/dispatcher.d that will be called on any network configuration change and such a script can then filter connection up events and start the notification script.
Related
I accidentally deleted my public and private key and had to generate new SSH keys due to not being able to restore the keys (and not having a backup anywhere). How do I change the public SSH key then of my Oracle Cloud instance?
Terminating the instance and remaking it isn't an option, and I've tried looking online but wasn't able to find much. Any help would be appreciated.
Thanks
Some background
Found a solution! Just so people are aware, there are methods online that involve connecting to the machine via VNC, but for me personally it felt very trial-an-error, when pressing buttons at the wrong time, and it ended up not working properly (VNC didn't display recovery mode for me, just a blank screen after selecting it).
Summary
This guide involves: Creating another machine (as incl. in free tier anyway), detaching the boot volume drive from the machine and attaching it to the machine just created, to do editing to change the keys over, then attaching the drive back up.
Create another VPS (Oracle have them incl. > free tier)
I deleted one of my other VPS' in the Oracle panel (that was a free machine - as I didn't need it and wasn't using it) and created it again anew (I made sure to delete the old boot volumes before continuing).
(This solution is assuming your using Ubuntu 20.04, but this will probably work for other OS's as well)
Basically from there,
I powered off the machine I wanted to change my SSH key of.
After fully being powered off, just detach the boot volume from the VPS, and attached it as a block volume to the machine just created.
Login to the machine via SSH, and run the connection commands by hitting the three dots (image below) and viewing the connection commands, to connect the drive up.
Editing files on the drive & mounting process
Then by running blkid (or sudo fdisk -l for a more friendly view)
you're able to see what drives are available for mounting. So then you just make a folder and simply type:
sudo mount [drive path e.g. /dev/sdb] [folder path e.g. ./drive]
Edit the file at /home/ubuntu/.ssh/authorized_keys, or however your machine is configured (Oracle by default disallows root, but if you've edited your configuration it's up to your end).
Then, simply go to the relevant path to be able to unmount the drive, umount [folder path e.g. ./drive]
Run the disconnect commands for the drive from the panel.
Then, simply detach the drive from your other machine and reattach it back to the original machine. Wait till it's fully attached and then start the machine again.
You can create a console connection, connection to it, then reboot the instance (through OCI console), and get to GRUB in the console connection... a few more steps and you can upload a new ssh key: https://docs.oracle.com/en-us/iaas/Content/Compute/References/serialconsole.htm
I have my GCP machine that is scheduled to switch on and run from 6hrs in the morning to 12hrs. I am trying to automate the script once the machine is on, so I am scheduling a job on 6:30 hrs.
But what I observed is that UIPath Robot doesn't automatically get connected unless I open an RDP session and then manually open UI Path Assistant to connect it with orchestrator.
I also tried to create a bat script and schedule it with windows startup. But that fails to run as well. To verify my startup script I added two commands:
<verification script sending mail on startup> && <UIPath Script>
I tested this script manually in RDP session and they did run sequentially as expected. But when I added it to auto-scheduling in gcp, only the first script actually ran (<verification script sending mail on startup>) and the second one (<UIPath Script>) just didn't.
Moreover I did put the bat file in Windows Startup Folder but again that also required me to sign into the system using RDP session for it to run.
From my understanding, the UIPath Script (XAML) in order to run needs the system to be switched on 24/7 and then it connects to orchestrator and then we can schedule the process based on the time, but then my maching will be idle for lots of ineffective hours.
Secondly, going by the .bat file to be as a startup script also fails as in order to run the script, it needs the user to be logged in which doesn't happen. Though other scripts such as .py files run smoothly so I lose here as well.
Finally scheduling my bat file through windows startup feature does work but then it's also of no use as for it to start also I need to open an RDP session and log in.
Does anyone know the workaround for this?
While working on machine xyz (could be linux or windows) - I need to start an executable program on another windows machine (just trigger would do).
How could that be done.
As per the comments provided, did the following purely on trial basis:
- Ran a custom listening tcl script on target machine (this was monitoring a shared file for writes) - also trying to use the win task scheduler to make it run each time user logs in
- On another machine that was to send command to the remote machine for exe execution, wrote a tcl proc to write to the shared file mentioned above
Thus whenever the file was written to, the script running on the target machine read the instructions and executed accordingly.
This is working for now, there are a few issues i am still facing but I think will get better eventually.
I have a Google Cloud Platform account that I access from a VirtualBox VM. I am using the Google Compute Engine for a project that I am currently working on, and I had to create a custom image based on the Ubuntu 14.04 image that's available there.
I made changes to the Ubuntu image by ssh'ing into an Ubuntu 14.04 instance, (from my Vbox VM terminal) installing the Matlab compiler runtime, and downloading some other files that I needed. I created the custom image by following the steps according to the documentation.
However, now the changes I made are only available to me when I SSH from my Vbox VM terminal. I need to be able to run a certain matlab program Via startup scripts, how can I make it so that all users using this image have access to the customizations I made? Is there a way I can do this without having to make the edits by ssh'ing from the developers console and redoing all the changes?
EDIT: I don't think I was very clear so Ill give some examples. say my Google account is alexanderlang. When I ssh into an instance created from my custom image from the developers console, bash prompt looks like:
alexanderlang#myinstance $
My Vbox username is alex, and when I ssh into the same instance from my vbox terminal, bash prompt looks like:
alex#myinstance $
alex#myinstance can run matlab programs, but alexanderlang#myinstance cannot. I'm talking about the same instance, created from the same image. I think this might have something to do with the ssh keys for my custom image, but I don't know how to change or remove those keys.
When you connect to your VM instance via ssh by using either Developers Console or gcloud, the user account is dynamically created (if it doesn't already exist) by setting metadata on the VM. The question is: how does each tool choose your username?
When you use Google Developers Console, the only information it knows about you is your Google Account name, so it uses that, e.g., <first-name>_<last-name> or similar.
When you connect to your instance via gcloud, it knows the value of $USER so it uses that instead.
Note that in either case, your account has passwordless sudo access, so if you want to switch from one account to the other, you can run:
sudo su alex
while logged in as alexanderlang and then you have access to all the programs that alex does.
Similarly, you can run:
sudo su alexanderlang
while logged in as alex to do the reverse.
Startup scripts run as root. To run commands as another user, you need to do two things:
change to that username
run commands as that user
sudo su alex will create a new shell and hence ignore the rest of the script (until you manually exit the user shell, which is not what you want).
You can use sudo su alex -c 'command to run' but since what you want to run is a complex script, you need to first save the script to a file, and then run it.
Your options are:
pre-create the shell script to run
dynamically generate it from the startup script
Doing (1) is easy if the script never changes. For frequently-changing scripts (and it sounds like, many dynamically created VMs), you want to use option (2).
Here's how to do this in a startup script:
cat > /tmp/startup-script-helper.sh <<EOF
# ... put the script contents here ...
EOF
sudo su alex -c '/tmp/startup-script-helper.sh'
You can use Packer to create a derived image from a stock GCE VM image. Packer will let you do the following very easily:
boot a GCE VM using an image you specify
run some customization step, e.g., shell script, or Chef/Puppet/etc.
save the resulting image in your Google Cloud Platform project
Then, you can boot any number of new VMs using your newly-created image.
Note that since your VM image will be stored on Google Cloud Storage, you will be charged for the space it uses. Current pricing for Google Cloud Storage standard class is USD $0.026 / GB / month. A typical VM image should be less than 1GB.
You can see a complete example of how I used Packer to build VMs and pre-installed Ambari on it via my GitHub repo.
I have my test writtern in Sikuli. If I RDP into my Jenkins machine and have an active session then all sikuli test pass.
However, for overnight run, my Jenkins machine do get locked. I want to understand if anyone has encountered and solved this issue before. Thanks!
Note: I cannot leave my Jenkins slave unlocked due to security reasons.
It's a known limitation of RDP.
Two optional solutions:
install VNC Server (like UltraVNC), and run it as Windows service (make sure it is launched during Windows logon).
OR
Create a batch file that disconnects Remote Desktop, and use it instead of closing the RDP session with the regular X button. The batch command is:
%windir%\system32\tscon.exe %SESSIONNAME% /dest:console