If ForwadX11 and ForwardX11Trusted are both enabled in /etc/ssh/ssh_config, when you do “ssh host” it will invoke X11 forwarding by default. This is convenient when you frequently need to run programs with GUI on remote host. However, with X11 forwarding, if you are simply running a text mode command/script via ssh, like “ssh node ls” […]
ssh pass password to sudo
echo <your password> | ssh <node name> “sudo -S <command>”
Recovering LVM from disk image
For a RAID NAS box, when the NAS box dies, the data on the drives are still intact. They can be retrieved in the following steps: dd disks containing LVM to hard drive; # create images of hard drives losetup /dev/loopx disks.img; # make images appear as loop devices on OS partx -v -add /dev/loopx; […]
bash script does not run command
Sometimes a bash script does not run the commands as cron or start up scripts that usually run when you debugging it. This may be caused by that the embedded running environment does not provide proper search path. To avoid this, always use full path to the executibles.
R upgrade all packages
update.packages(checkBuilt=TRUE, ask=FALSE)
Fedora copy paste not working
The convenient select copy, mouse middle click paste way does not work on some Fedora desktop environment. Even the Ctrl-C/Ctrl-V/Ctrl-X copy past and menu copy-paste does not work, forcing users to hand type in things that usually just a few mouse clicks away. This is identified as a buggy package called “clipit” To identify the […]
Avoid duplicates in $PATH
Linux search /etc/profile.d and ~/.bashrc, ~/.bash_profile for system and user defined environmental variables. One of the most manipulated variable is $PATH. You can see this by running $ echo $PATH In most cases, when a new 3rd party software is installed, and you want it to be in your default executable search path, you insert […]
Installing Lapack in CentOS 7-8
For CentOS7, ccmake -DCMAKE_INSTALL_PREFIX=/usr/local/lapack -DCMAKE_BUILD_TYPE=RELEASE -DBUILD_SHARED_LIBS=ON -DLAPACKE=ON .. Then make, make install will get you a working version of liblapacke.so The current version 3.8.0 source has bugs that prevent the .so to work properly. Version 3.7.1 is the best to do. For CentOS8, the Fedora 29 version of Lapack works by dnf install.
Ganglia cannot display cluster view with certain version of php
This is related with a version compatibility issue. nano +26 /usr/share/ganglia/cluster_view.php change $context_metrics = “”; to $context_metrics = array(); will do the job.
kill zombies
A zombie is already dead, so you cannot kill it. To clean up a zombie, it must be waited on by its parent, so killing the parent should work to eliminate the zombie. An example of how you might send a signal to every process that is the parent of a zombie (note that this […]