How to Check Ubuntu Version from the Command Line

lsb_release -a
https://linuxize.com/post/how-to-check-your-ubuntu-version/

How to get tail like functionality on windows with powershell

https://www.howtogeek.com/tips/how-to-get-tail-like-functionality-on-windows-with-powershell/

Error starting userland proxy: listen tcp 0.0.0.0:5432: bind: address already in use

This issue happens when I installed Postgres in my vagrant (vm) and then I after a while I removed it. But the service is still running in the system causing the default 5432 port is not available to be used.





first I run this command

sudo apt-get --purge remove postgresql

but still, it didn't totally remove. so I have to run this command to list all running postgres

dpkg -l | grep postgres

then, I run again this command

sudo apt-get --purge remove postgresql postgresql-doc postgresql-common

Eureka!

Thanks for this reference
https://askubuntu.com/questions/32730/how-to-remove-postgres-from-my-installation

useful unix commands

to see all processes
ps -aef | more
ps -aef | sort | more
ps -aef | sort > out.txt

curl: (60) Peer's Certificate issuer is not recognized

After our company implements stricter rules, I can't install docker in my vagrant properly. I have been solving this issue for about a week and its hard to point out the correct solution until I found from stackoverflow.

add this in vagrant file
config.vm.box_download_ca_cert = "./Fortinet_CA_SSL.cer"

Finally fixed it. Post the answer here as reference.

• Export company trusted root certificate with .cer extension. Somthing naming external root certificate
• Convert the ca file to .pem file using openssl x509 -in xxx.cer -inform der -outform pem -out xxx.pem

Then on the centos 7 os:

• Install the ca-certificates package: yum install ca-certificates
• Enable the dynamic CA configuration feature: update-ca-trust force-enable
• Add the exported pem files to /etc/pki/ca-trust/source/anchors/
• Use command: update-ca-trust extract

https://stackoverflow.com/questions/47676980/curl-60-peers-certificate-issuer-is-not-recognized

no valid OpenPGP data found

problem:

Fix: is not in the sudoers file. This incident will be reported.

lynard is not in the sudoers file.  This incident will be reported.

switch to root
sudo usermod -g sudo lynard 



Eureka!

Permanent aliases

Sometimes typing docker-compose up is too long to type. The best to make it shorter is to create aliases like alias ll="ls -al" but this is only temporary.

To make it a permanent aliases edit the ~/.bashrc and add the following
# some more ls aliases
alias ll='ls -alF'
alias la='ls -A'
alias l='ls -CF'
alias dbup='docker-compose up -d db'
alias up='docker-compose up app'
alias stop='docker-compose stop'
alias re='docker-compose restart'
alias logs='docker-compose logs -f --tail 10'





refresh

source ~/.bashrc

Eureka!

How to make folder writable in ubuntu

That makes the directory writable, readable and executable by anybody

sudo chmod 777 directory


It will give all permission except write by anybody.

sudo chmod 775 'your directory'

Cron job

sudo crontab -e


# ┌───────────── minute (0 - 59)
# │ ┌───────────── hour (0 - 23)
# │ │ ┌───────────── day of month (1 - 31)
# │ │ │ ┌───────────── month (1 - 12)
# │ │ │ │ ┌───────────── day of week (0 - 6) (Sunday to Saturday; 7 is also Sunday on some systems)
# │ │ │ │ │
# │ │ │ │ │
# │ │ │ │ │
# * * * * * command_to_execute

0 0 * * * /opt/odoo12/run_backup.sh

Rsync (Remote Sync)

Every time I create a new odoo instance is that I always copy my source code to a new odoo folder setup. It's not only time-consuming but every time I need to edit a single source code I also need to edit the other source code. bit confusing? anyway, I'm the only one who understands. :)

I found this Linux command and I think it is very useful. The last time I remember that I have encountered this kind of command but didn't think of it much how useful it is.

so here we go, without further ado.

first install the tool
sudo apt-get install rsync

sudo rsync -avzh /odoo/trunk/app/customaddons /odoo/sit3/app

eureka!

reference:

https://www.tecmint.com/rsync-local-remote-file-synchronization-commands/

How to know what OS installed

Linux

cat /etc/*release

automate calling curl

while true; do curl localhost:8869; sleep .5; done

To change user password in linux

sudo passwd user

To add user in linux

adduser --home /home/deploy --shell /bin/bash deploy

Change user and group permission in linux

problem:

solution:
sudo chown -R odoo:odoo vbroker20-beta2

references:

https://www.thegeekstuff.com/2012/06/chown-examples

VBoxGuestAdditions in vagrant centos

1. sudo yum update && sudo yum -y install kernel-headers kernel-devel

2. manually by downloading the iso file inside VM (e.g. wget) and installing it, e.g.

wget http://download.virtualbox.org/virtualbox/5.0.16/VBoxGuestAdditions_5.0.16.iso -P /tmp

(read only to write permission)
sudo chmod 777 /tmp/VBoxGuestAdditions_5.0.16.iso

sudo mount -o loop /tmp/VBoxGuestAdditions_5.0.16.iso /mnt

(install libraries)
sudo yum -y install gcc
sudo yum install freeglut-devel
sudo yum install mesa*

sudo sh -x /mnt/VBoxLinuxAdditions.run # --keep


forget all the commands above , just download the geerlingguy/centos7

that's it!!! voila

fluentd the new logging

while working in one of my freelance jobs, I encountered this logging technology fluentd. It is quite interesting, hopefully can learn with this new technology.

I have installed in my centos operating system

curl -L https://toolbelt.treasuredata.com/sh/install-redhat-td-agent3.sh | sh

References:
https://docs.fluentd.org

Linux command

To set new password for root in Ubuntu
> sudo passwd root


To locate a file
find / -name 'pg_hba.conf' 2>/dev/null


To add new user
> sudo adduser --home /home/demo --shell /bin/bash demo

Install VirtualBox guest additions in CentOS

Open up the virtualbox centos gui

type:
su -
yum update kernel*
yum -y install kernel-devel kernel-headers dkms gcc gcc-c++
reboot

insert virtual optical disk in settings
mount /dev/cdrom /mnt
cd /mnt
./VBoxLinuxAdditions.run

Merci!

References:
http://nanxiao.me/en/install-virtualbox-guest-additions/