Windows screen shots via command-line SSH session

command linescreenshotsshwindows

I've browsed the handful of "screen capture" queries here, but I was unable to find anything which addressed my specific need.

I'm looking for a command-line tool that I can run via remote SSH connection (by way of the cygwin sshd daemon). There are several to choose from, but the few I've tried (ImageMagick, nircmd, and MiniCap) all result in a blank screen. I assume that this is due to the remotely logged in user not having a proper graphical console session running.

The goal here is automate screen capture and retrieval of the main system console (what one would see if they were looking at the physical monitor) through the use of ssh script from a Unix host:

ssh user@windowshost "screencap --output /tmp/console.jpg"
scp user@windowshost:/tmp/console.jpg /some/destdir

Note that these must be done on demand, so polling a remote directory that has snapshots dumped periodically will not work.

Bonus points for programs that are open source and have a portable install (so I don't need to RDP/VNC into the machine to run a graphical installer).

Best Answer

If you already have VNC on the machine you may try to make screenshots through VNC, e.g. with VNC Snapshot.

Related Solutions

How to Take a Screenshot from Command Line in Windows

Download imagemagick. Many command line image manipulation tools are included. import allows you to capture some or all of a screen and save the image to a file. For example, to save the entire screen as a jpeg:

import -window root screen.jpeg

If you want to use the mouse to click inside a window or select a screen region & save a a png, just use:

import box.png

Linux – ssh-agent and screen

With the following setup, you won't need any wrapper for invoking screen. Moreover, it avoids using /tmp (with the consequent security risks).

Ensure you have an ~/tmp directory:
```
mkdir ~/tmp
```
Add to .screenrc the following line:
```
setenv SSH_AUTH_SOCK "$HOME/tmp/ssh-agent-screen"
```
- This ensures that inside screen, ssh looks for the socket always in the same location, rather than a changing path.
- You must use setenv whichever shell you use, since it's a screen and not a shell command.
Add to .bash_profile the following line:
```
[ -n "$SSH_AUTH_SOCK" ] && [ "$SSH_AUTH_SOCK"!="$HOME/tmp/ssh-agent-screen" ] && ln -sf "$SSH_AUTH_SOCK" "$HOME/tmp/ssh-agent-screen"
```
- This will link from the fixed location (where ssh looks) to the real one, and must appear after starting ssh-agent.
- Using [ -n "$SSH_AUTH_SOCK" ] will properly prevent errors when SSH_AUTH_SOCK is not set.
- [ "$SSH_AUTH_SOCK"!="$HOME/tmp/ssh-agent-screen" ] will prevent screen sessions linking $HOME/tmp/ssh-agent-screen to itself, if screen sources .bash_profile.
Instead of starting ssh-agent in .bash_profile, you can consider connecting with ssh -A (to use agent forwarding and make the remote machine use your agent).

After this setup, you can just use standard screen command. You'll only need to recreate existing sessions or manually set SSH_AUTH_SOCK inside them to the fixed location of step 2.

Credits to this website for the idea; I avoided using /tmp. This answer is similar but uses extra aliases.

Best Answer

Related Solutions

How to Take a Screenshot from Command Line in Windows

Linux – ssh-agent and screen

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