How to turn the screen blanking/sleep mode off under CentOS 7? - linux

After a few minutes my freshly installed minimal CentOS installation blanks the screen and disconnects the WiFi. The system wakes back up, when I hit any key. I am under the suspicion that this is related to the setting of the screen blanking and/or sleep mode.
I've found a few hints on the web but most of them revolve around window manager settings (I do not have a window manager installed). One that seems to do something, I already tried:
sudo setterm -powersave off -blank 0
This command does not yield any output but it doesn't fix the problem either: The system keeps to blank the screen after a while.
The iwconfig sleep mode device setting is not available since NetworkManager is installed.

Apparently it worked but not permanently (the setting is reset at reboot). I added the line
setterm -powersave off -blank 0
to my /etc/rc.d/rc.local file and made it executable. This way the setting is set again at boot time.

Related

Create shell script to reboot linux in case of incorrect shutdown

I have Raspbian Jessie 8 running in a Raspberry Pi 3. There are 3 JavaScript services that are automatically started by PM2.
However, if the Raspberry is shutdown incorrectly, e.g., if the energy cable is removed, the services don't start.
They only start automatically if the Raspberry is shutdown properly, e.g., using sudo reboot.
I need a shell script that checks if the Raspberry was incorrectly shutdown and, if it was, to be rebooted using sudo reboot.
I saw here and here how to create a simple reboot script and here how to check if a service is running, but found nothing on how to check for an improper shutdown. Can anyone tell me how?
You can always put your services start in the legacy startup-file /etc/rc.local that is a shell script called as the very last thing in the startup. Make sure its executable.

Black Console after automated Debian UEFI install

I try to build a reproducible automated build environment based on Debian 8.1 Jessie.
I created a boot iso image based on a netinstall image and put a preseed.cfg file in int for automatic installation.
I managed to get it bootable with BIOS and UEFI and can install a KDE Developer Debian in VMWare Workstation 11 fully automated.
I have also a server iso image to install a debian Server with Jenkins, both with BIOS and UEFI Boot.
But after the installation, the Version with UEFI Boot shows a black Screen when started.
I can blindly log in, start the gui with "startx" and see my installed xfce desktop. When i quit xfce the console is usable and visible.
I tried suggested bootparameters "nomodeset" and "vga=Linux" that i found with google to no avail.
I also tried to debug the boot prozess, to find out which command leads to a blank screen, but i did not find the right place to delay the processes at bootup so i can see when the messages dissapear (quiet bootparameter was removed :-)
I also tried to reset the console to no avail.
Can anybode point me to a tool that does the same "switching" like X so the console is useable?
Can anybody give me some hints how to debug the bootprocess to find out which command is causing this behaviour?
I dont want to install X because this should be a headless server system later.
I managed to get my system to boot using the kernel command line modprobe.blacklist=vmwgfx, or placing 'blacklist vmwgfx' in /etc/modprobe.d/*.conf
I assume it is some bug in the vmwgfx module, however as this workaround works for me I have no immediate need to investigate further.

Screen tool on Galileo

I have compiled and installed screen tool on Galileo running on Yocto.
http://www.gnu.org/software/screen/
When I run the tool everything is OK, I can create many sessions. However when I close the terminal all my sessions are closed (when I do "screen -ls" from other terminal there are no sockets). This is not happening in any other Linux distribution.
Regards,
Yevgeniy
Are you running screen from inside a ssh connection? There was a bug in earlier releases of the devkit where on disconnect systemd killed all processes started by the daemon, which isn't what you want. This has been fixed so upgrading your image should be sufficient.
If you can't get the upgrade, the fix is to add "KillMode=process" to the end of /lib/systemd/system/ssh#.service.

SSH tunnelling into arch box

I have a raspberry pi running arch linux connected to the TV and want to run commands on that screen by SSH'ing from my Ubuntu machine elsewhere.
I have tried running the command SSH -Y root# and starting xclock as a test. However I get the following error:
No protocol specified
Error: Can't open display: :0
I then tried running "export DISPLAY=:0" on the arch machine, but this doesn't solve the issue.
I have X running fine and can see it on the TV and I have edited the file /etc/ssh/ssh_config to allow X11 forwarding.
Anyone know what I am doing wrong?
Many thanks
The ArchLinux wiki has some good instructions on setting things up. I struggled for a while until I found them, but for me the key was to set up SSH forwarding within sshd_config (most distros seem to enable this by default, but Arch doesn't).
Once you've enabled X forwarding in SSHD, I also found it helpful to install the dummy video driver for Xorg ("pacman -S xf86-video-dummy"), which gets rid of irritating errors about missing the RANDR extension. This might not be necessary if you already have it running a real X server locally on the Pi - personally, I'm running mine completely headless.
I've found that I don't have to worry about setting up the DISPLAY variable, or xhost, when running with 'ssh -X' from an iMac. I'd expect Ubuntu to behave the same.
looks like an authentication problem. The answer used to be
xhost +
on the console of the X display. Might help.
You probably want to set
export DISPLAY=[IP_ADDRESS_OF_ARCH_BOX]:0
on your Ubuntu box, then when you run xclock from your Ubuntu box, it'll forward the screen to the Arch box.

Attach/Detach to a remote instance of Eclipse

When using Eclipse over X-Windows on a remote shell (X port forwarding), is there a way to simply detach my X connection and come back to the process later. For a little more clarity, I'm on a Windows machine and have to reboot. I'd like to keep Eclipse running and come back where I left off. Eclipse is running on my Windows machine through an X-Server connected to a Linux box.
I'm thinking something like tmux could do the trick. However, I do a Ctrl-Z to stop Eclipse and it won't close the Eclipse Window. If I restart the X-Server in Windows, Eclipse fails when I try fg 1. Any other options?
Xpra did everything that I needed, but it was not clear exactly how it worked. I was able to get it working by opening two PuTTY sessions in windows, one server and one client. Also, the Google Code is out-dated. Instead, install from http://xpra.devloop.org.uk/dists/xpra-0.0.7.9.tar.bz2. I'm not sure how it's different, but it worked for me. The README tells how to build the package. It is necessary to apt-get a bunch of other stuff. But, here are the missing pieces on how to get it work as I describe above:
Setup server:
cd ~/download/xpra/xpra-0.0.7.9
export PYTHONPATH=$PWD/install/lib/python:$PYTHONPATH
./install/bin/xpra start :10
export DISPLAY=:10
xterm&
Setup client:
cd ~/download/xpra/xpra-0.0.7.9
export PYTHONPATH=$PWD/install/lib/python:$PYTHONPATH
./install/bin/xpra attach :10
Notes:
The Windows xpra installer is not needed for this configuration. I don't know what it's supposed to do.
Be sure to run Xming on Windows.
Be sure to enable X port forwarding on the client PuTTY window.
Launch whatever you want from the xterm window. (ie Eclipse)
You can close the server window once xterm is up.
Hit ctrl-c in the client window to detach from the session.
Do all the client commands again to re-attach..even after restarting PuTTY, the Xming, or Windows itself.
I have zero experience with it, but xpra sounds like exactly what you're looking for.

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