Find your public IP address from linux command line

Problem

You would like to find out your public IP from the command line without using an online service

Solution

Use dig like the following line (taken from https://www.cyberciti.biz/faq/how-to-find-my-public-ip-address-from-command-line-on-a-linux/):

dig +short myip.opendns.com @resolver1.opendns.com

you could also add it as an alias:

alias myip=”dig +short myip.opendns.com @resolver1.opendns.com”

WARN[0000] Your Skaffold version might be too old. Download the latest version (1.0.1) at https://storage.googleapis.com/skaffold/releases/latest/skaffold-linux-amd64

Problem

You would like to follow the example for working with skaffold by using the skaffold dev command but you are getting the following error:

kosmas:getting-started (master)$ skaffold dev
WARN[0000] Your Skaffold version might be too old. Download the latest version (1.0.1) at https://storage.googleapis.com/skaffold/releases/latest/skaffold-linux-amd64 

Solution

Download the latest release from here https://github.com/GoogleContainerTools/skaffold/releases and follow the instructions for installing it in your system (ie linux):

 curl -Lo skaffold https://storage.googleapis.com/skaffold/releases/v1.0.1/skaffold-linux-amd64 && chmod +x skaffold && sudo mv skaffold /usr/local/bin

Using nginx to redirect to a different port

Problem

You have a docker container with an application running in a port different than port 80 (ie port 3000), and would like to access it without specifying the port, by using the domain name only.

Solution

Use the nginx proxy_pass as follows:

server {
  listen 80;

  server_name your_server_domain_name.com;
  location / {
    proxy_set_header  X-Real-IP $remote_addr;
    proxy_set_header  Host $http_host;
    proxy_pass        http://127.0.0.1:3000;
  }
}

Removing DEFINER from MySQL < 5.7 dump files

Problem

You are using the dump files from MySQL (earlier version than 5.7 – that has -skip-definer option in mysqlpump), that outputs the DEFINER keyword in Functions and Views, which causes en error when trying to import in a different database that the users do not exist.

Solution

Use the following in your database dump to remove these keywords:

For FUNCTIONS

sed -i 's/DEFINER=\S*\sFUNCTION/FUNCTION/' mysql_dump

For VIEWS

sed -i '/50013\sDEFINER/d' mysql_dump

Find your Thinkpad (X1) model type in linux

Problem

You would like to find out the exact model from your Thinkpad X1 laptop, by using your linux command line.

Solution

Use the following command:

kosmas:$ sudo dmidecode | grep -A3 '^System Information'
[sudo] password for kosmas: 
System Information
        Manufacturer: LENOVO
        Product Name: 20HRCTO1WW
        Version: ThinkPad X1 Carbon 5th

Find files between specific times using find

Problem

You would like to find the files modified between certain times using find

Solution

Use the following find command using the -newerXY parameter to specify times you want to look for (ie betwen 2019-09-23 06:00:00 and 2019-09-23 10:00:00)

find . -type f -newermt "2019-09-23 06:00:00" ! -newermt "2019-09-23 10:00:00" | xargs ls -tral

Problems using snap autossh

Problem

You would like to use autossh to keep a connection open (ie database) between two hosts, but while the ssh equivalent command to start a tunnel works, the autossh does not.

You might be seeing the following errors (using AUTOSSH_DEBUG=1):

autossh[7471]: ssh exited prematurely with status 255; autossh exiting

or if you look at /var/logs/syslog you could also see entries like the following:

 apparmor="DENIED" operation="open" profile="snap.autossh.autossh" name="/home/autossh/.ssh/id_rsa.pub" pid=7447 comm="ssh" requested_mask="r" denied_mask="r" fsuid=1002 ouid=1002

Solution

You have used snap to install autossh which is not allowed by apparmor.

Remove the snap package and install autossh as a normal debian package:

sudo snap remove autossh
sudo apt install autossh