Tech Tips

Unable to rename in go projects in vscode

2020-06-14T23:27:00.001+03:00

vscode used to use gorename to do the renames. However, gorename does not support go modules. gopls should be used instead. If it is not available to your project, try to add the following in your configuration file:


  "go.languageServerExperimentalFeatures": {
    "rename": true
}

Run command on suspend

2020-03-22T20:39:00.001+03:00

Create a file located in /usr/lib/systemd/system-sleep directory:

#!/bin/sh
if [ "${1}" == "pre" ]; then
  nordvpn d
elif [ "${1}" == "post" ]; then
  echo "Hello"
fi

Debug route table

2020-03-03T18:21:00.001+03:00

List all routes in system:

route -n

Get route for a specific IP:

ip route get 1.1.1.1

Log denied connections in firewalld

2020-03-03T13:21:00.001+03:00

Edit filr /etc/sysconfig/firewalld:

FIREWALLD_ARGS=--debug=10

Wait until able to connect

2020-02-14T18:13:00.001+03:00

while ! nc -w5 -z 10.0.0.100 22; do echo "hello"; done

Log executed command

2020-02-14T18:12:00.001+03:00

14:27 $ (set -x; sleep 1 && sleep 2)
+ sleep 1
+ sleep 2

Check and modify connection mtu

2020-01-30T15:46:00.001+03:00

To check:

[root@lxd-node3 ~]# netstat -i
Kernel Interface table
Iface             MTU    RX-OK RX-ERR RX-DRP RX-OVR    TX-OK TX-ERR TX-DRP TX-OVR Flg
ens10            1450      455      0      0 0           671      0      0      0 BMRU
eth0             1500       28      0      0 0            32      0      0      0 BMRU
lo              65536        0      0      0 0             0      0      0      0 LRU

Modify temporarily:

ifconfig eth0 mtu 1450

Permanently: edit /etc/sysconfig/network-scripts/ifcfg-eth0 file and add:

MTU=1450

lxd: Fix version in snap

2020-01-23T14:52:00.001+03:00

 snap refresh lxd --channel=3.18

fedora: Lockdown a kernel version

2020-01-23T00:16:00.001+03:00

Fedora typically keeps 3 latest kernel versions. However, what if you want to keep an old specific kernel version which is known to work well with your system? First, we need to install a dnf plugin that allows us to keep a specific version of any package:

sudo dnf install python3-dnf-plugins-extras-versionlock

Lets find all available kernel versions for your system:

sudo dnf list kernel --showduplicates

Install that specific version of the kernel:

sudo dnf install kernel-5.3.7-301.fc31

And lock it:

sudo dnf versionlock add kernel-5.3.7-301.fc31

To remove the lock:

sudo dnf versionlock delete kernel-5.3.7-301.fc31

Dell Precision 5540 - Battery drains in sleep mode

2020-01-02T18:10:00.001+03:00

Run the following command to check the suspend mode:

cat /sys/power/mem_sleep

If the output looks like this:

[s2idle] deep

It means that very inefficient suspend mode is active (drains battery from 100% to 0 in 9 hours). To enable "deep" mode, edit file /etc/default/grub and append "mem_sleep_default=deep" to GRUB_CMDLINE_LINUX:

GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)"
GRUB_DEFAULT=saved
GRUB_DISABLE_SUBMENU=true
GRUB_TERMINAL_OUTPUT="console"
GRUB_CMDLINE_LINUX="rd.lvm.lv=fedora/root rd.lvm.lv=fedora/swap rhgb quiet mem_sleep_default=deep"
GRUB_DISABLE_RECOVERY="true"
GRUB_ENABLE_BLSCFG=true

Apply changes:

sudo grub2-mkconfig -o /boot/efi/EFI/fedora/grub.cfg

Restart your laptop and verify changes:

$ cat /sys/power/mem_sleep 
s2idle [deep]

Increase storage of a lxd container

2019-12-23T16:02:00.001+03:00

By default lxd stopped to assign root (disk) device to a container. To modify storage volume of a container add a device like this:

lxc config device add surflyc root disk pool=default path=/ size=15GB

Restart the container to apply changes.

Log quireis in dnsmasq

2019-12-23T15:38:00.001+03:00

Add the following line to dnsmasq configuration file: log-queries

Lxd on Fedora 31

2019-11-22T01:36:00.001+03:00

Fedora 31 has started to use cgroups v2 by default. According to Common F31 bugs it doesn't play nice with Docker, lxd and others. To make fedora switch back to the old cgroups:

sudo grubby --update-kernel=ALL --args="systemd.unified_cgroup_hierarchy=0"

How to regenerate grub configuration

2019-11-22T01:32:00.001+03:00

sudo grub2-mkconfig -o /boot/efi/EFI/fedora/grub.cfg

wifi utils

2019-10-04T15:05:00.001+03:00

List used wifi frequences

sudo iwlist wlp1s0 scan | grep Frequency | sort | uniq -c | sort -n

List available channels

iwlist channel

List wifi networks

nmcli d wifi

Fix isort in vscode for python2

2019-09-25T12:56:00.000+03:00

Go to the vscode Python extension folder:

cd ~/.vscode/extensions/ms-python.python-2019.9.34911

Install latest version that is known to work with python 2:

pip2 install -t ./pythonFiles/lib/python --upgrade isort==4.3.17

python: Django-like testrunner

2018-03-11T02:28:00.001+03:00

Django-like testrunner for non-django projects:

#!/usr/bin/env python

import argparse
import collections
import unittest
import sys


def main():
    parser = argparse.ArgumentParser(description='Django-like testrunner')
    parser.add_argument('specific_test', metavar='', type=str, nargs='?', help='Specifc test')
    parser.add_argument("--failfast", action="store_true")
    parser.add_argument("--verbosity", type=int, default=1)

    args = parser.parse_args()

    loader = unittest.TestLoader()
    all_tests = loader.discover('.', top_level_dir="./")
    suite = unittest.TestSuite()

    if args.specific_test:

        def walk_tests(tests):
            if isinstance(tests, collections.Iterable):
                for item in tests:
                    walk_tests(item)
                return
            if tests.id().startswith(args.specific_test):
                suite.addTest(tests)
            elif not str(tests).startswith("test"):
                sys.exit("Error in file %s" % tests)

        walk_tests(all_tests)
    else:
        suite.addTests(all_tests)

    unittest.TextTestRunner(verbosity=args.verbosity, failfast=args.failfast).run(suite)


if __name__ == "__main__":
    main()

fedora: SSL certificate viewer

2018-03-11T02:23:00.001+03:00

GUI to view certificate:

gcr-viewer cert.pem

linux: List all IP addresses in a network

2018-03-11T02:22:00.001+03:00

To list ip addresses of all connected to the network devices, use this command:

nmap -sn 192.168.0.0/24

linux: CPU benchmark

2018-03-11T02:20:00.001+03:00

$ sysbench cpu run --time=5
sysbench 1.0.9 (using system LuaJIT 2.1.0-beta3)

Running the test with following options:
Number of threads: 1
Initializing random number generator from current time


Prime numbers limit: 10000

Initializing worker threads...

Threads started!

CPU speed:
    events per second:  1157.88

General statistics:
    total time:                          5.0008s
    total number of events:              5792

Latency (ms):
         min:                                  0.80
         avg:                                  0.86
         max:                                  3.74
         95th percentile:                      1.06
         sum:                               4998.26

Threads fairness:
    events (avg/stddev):           5792.0000/0.00
    execution time (avg/stddev):   4.9983/0.00

bash: How to check what hides behind an alias

2018-03-11T02:19:00.001+03:00

To check what command is assigned to the alias use type command:

$ type gl
gl is aliased to `git log --oneline'

fedora: Install flashplayer in Firefox

2017-11-16T16:31:00.001+03:00

I have flashplayer installed on my system from the official Adobe repository, but Firefox for some reason does not have flash plugin installed. You can check if your browser supports flash by navigating to this url

To make Firefox aware of flashplugin, try to create a symlink here:

cd http://isflashinstalled.com/ && ln -s /usr/lib64/flash-plugin/libflashplayer.so .

Monitor process with top

2017-11-02T16:23:00.001+03:00

One liner to monitor a process with the name /wshub:

top -p "$(pgrep -f /wshub)"

Run command as a different user

2017-10-31T17:20:00.001+03:00

Command runuser allows to run a command as a different user. You must be root to be able to run that command:

sudo runuser -l vagrant -c "GH=1 env"

Monitor cpu and memory usage of the process

2017-10-13T00:35:00.001+03:00

Print every second cpu and memory usage of the process:

watch -n 1 "ps -eo pid,pcpu,pmem,args | kazy -i xnotitle -e kazy"