System monitoring

I was looking for a system monitoring solution that can notify my in case of abnormal CPU/netowrk/disk usage via email or telegram. It seems there are several popular solutions: * `Nagios `_ * `Munin `_ * `Icinga `_ * `Spiceworks `_ * `Monit `_ * `Cacti `_ * `Zabbix `_ * `Glances `_ * `Monitorix `_ See also: * ``_

March 22, 2020 · SergeM

Robocar project

For the robocar contest in Berlin I started a project of building an autonomous toy car (scale 1:10). The goal of the contest was to show the fastest lap driving autonomously. The track had 8-shape with lane boundaries marked with white tape. Unfortunately the competition got cancelled. But that gave me an opportunity to switch from my 1st gen car to 2nd gen version. Here is my first version: The second version is built upon a stock RC car Absima Abs1...

August 24, 2019 · SergeM

ROS experience

ROS on raspberry pi There is a compiled image for RPi by ubiquity that has ROS kinetic: It seems for me too old. It’s 2020, there are ubuntu 18, ros melodic and ros2, next year the support of python2.7 will be discontinued. Meh… It is possible to have ROS melodic on Raspberry Pi 3 B+. See in the next sections. Installing tensorflow for ROS on raspberry pi Alternatively one can try to install it from wheels: https://www....

August 24, 2019 · SergeM

Reducing disk usage in Ubuntu

Here are some recipies to make ubuntu installed on USB drive to work faster. [1] [2] reducing swapping Add these lines to /etc/sysctl.conf, and reboot. vm.swappiness = 0 vm.dirty_background_ratio = 20 vm.dirty_expire_centisecs = 0 vm.dirty_ratio = 80 vm.dirty_writeback_centisecs = 0 More caching while writting on disk Add noatime,commit=120,… to /etc/fstab entries for / and /home

August 16, 2018 · SergeM

Ubuntu/linux settings

Some settings I find useful for a workstation CPU monitoring on the main panel Default Ubuntu desktop seems to become finally convenient enough for me starting from Ubuntu 18.04. Only several tweaks are missing. Constantly available CPU/Mem/HDD/Network monitor is one of them. Here is how to install a small widget for a top panel in the default GNOME desktop environment. sudo apt-get install gir1.2-gtop-2.0 gir1.2-networkmanager-1.0 gir1.2-clutter-1.0 Go to Ubuntu Software and then search for system monitor extension....

January 11, 2018 · SergeM

Useful console commands

Some linux commands that I’ll probably need in the future User management Add user to a group sudo usermod -aG group user or sudo adduser <user> <group> Delete user userdel user Delete the user’s home directory and mail spool: userdel -r user Remove user from a group sudo gpasswd -d user group list all users: $ getent passwd list all groups: $ getent group list all groups of the current user:...

June 9, 2017 · SergeM

Combine images to PDF in linux

Using convert utility we can join multiple image files (png, jpeg, pdf) into one pdf. convert -density 250 file1.pdf file2.JPG file3.pdf -compress JPEG -quality 70 combined.pdf we use JPEG compression with quality =90 for images inside PDF. Otherwise the PDF will be too large. source For me images appear rotated inside the pdf. That’s probably because EXIF information about image rotation is not taken into account by pdf converter. You can remove all the meta information first with convert <input file> -strip <output file> and then combine it to a pdf....

May 3, 2017 · SergeM

How to hide Firefox title bar in Cinnamon (mint)

Source here Install devilspie: sudo apt-get install devilspie There is also a gui called gdevilspie, but the rules it produced seemed inaccurate and often didn’t quite work, so it is easiest to concoct a rule by reading the readme and the manpage. How the rule was created All rules created must go in ~/.devilspie, and have a .ds extension, so firstly create the folder if it doesn’t exist with mkdir ~/....

April 13, 2017 · SergeM

SSH cheat sheet

Create more secure ssh keys Create a key using elliptic curve cryptography (more secure): ssh-keygen -a 100 -t ed25519 generate RSA key of length 4096 to file my_key ssh-keygen -t rsa -b 4096 -C "" -f my_key Generate md5 fingerprint of the key (works in newer ubuntu, 16): ssh-keygen -lf ./my_key -E md5 see also: Upgrade Your SSH Key to Ed25519 How to prevent SSH from scanning all the keys in ....

April 12, 2017 · SergeM

"No protocol specified" while running a program as another user

Running some GUI application as another user: user1@laptop:~$ su - user2 user2@laptop:~$ leafpad ~/somefile.txt No protocol specified The problem is user2 doesn’t have access to your screen. Solution: xhost + Probably not the safest one. Source: thread

March 30, 2017 · SergeM