To create an rrd datbase file needs a certain amount of understanding of what you monitor, and for how long the data needs to be kept, and of course, storage space is also a consideration when creating a new rrd … Continue reading
Dimension rrdtool databases with years worth of values
Posted in Database, Monitoring
Tagged database, rrdtools
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Configuring vim for dark terminal windows
On CentOS, vim is installed with a default configuration. These defaults might be right for some users but not for everyone. I will describe the two settings I personally find most annoying for my setup. One of the assumtions in the … Continue reading
Recompress git repository
Git repositories are getting bigger and bigger. To reduce the disk space used by a repository, git provides some housekeeping functionality. Compared to other version control systems, git stores the complete history in each cloned repository if not told otherwise. This can … Continue reading
Modify file and directory date
Sometimes it is necessary to change a file or even a directory’s timestamp. This sounds easy, but most GUI utilities installed out of the box on OS X as well as on Linux don’t let you change a file’s timestamp. … Continue reading
Posted in Linux Administration, MacOSX
Tagged date, touch
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Shrink sparse cqow2 disc image
There might be cases when a VM temporarily used a lot of disk space which is then not needed any more. The sparse disk image format qcow2 will grow as the disk space is used, but it does not automatically shrink. … Continue reading
Posted in Linux Administration, Virtualisation
Tagged qcow2, qemu
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Perform a portscan using netcat
To perform a port scan, most of the time we think about a separate program. Sometimes it is not necessary to look that far. On most Linux systems netcat is already installed or can be installed easily from a repository. Continue reading
Posted in Linux Administration, Security
Tagged nc, netcat, portscan
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Restrict SSH access to port forwarding to one specific port
Allowing access to an unprotected service on a server is always a problem. Sometimes the easiest way is to not expose this service to the network but allow access via ssh port-forwarding, but how to limit the SSH account to … Continue reading
Posted in Linux Administration, Security
Tagged port forwarding, SSH
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Generate public SSH key from private SSH key
A lost SSH public-key or a web service generates an SSH key but does not provide the public-key part to you. What to do now? There is a solution for this situation. Continue reading
Posted in Linux Administration, Security
Tagged SSH, ssh key
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Review: iPhone 6 Battery Charger Case
In today’s world the smartphone has become the mobile communication center in our pocket. All the wireless technologies around us communicate with our smartphones. Wireless technologies drain the battery, but there is a way to extend the battery life. When using … Continue reading
Managing shell commands and processes
Not every command you might execute only runs for a couple of seconds. When you have a long running command a couple of problems can come with it. When the ssh connection is not stable, the command might be interrupted, … Continue reading
Posted in Linux Administration
Tagged bash, screen, SSH
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