Uly.me

cloud engineer

Archives for June 2020

Linux Script

The script command records all your keystrokes and output into a file called typescript.

You can start recording by simply typing script.

script
Script started, file is typescript
df -h
ls -l
exit

Typing exit stops the recording. Just cat typescript to see your recording.

cat typescript

PHP 7.0 to 7.4 Upgrade

Here are steps I took to upgrade from PHP 7.0 to 7.4 on Ubuntu 18.04 LTS.

Login as root, otherwise use sudo for all commands.

# use 3rd party ppa repo
add-apt-repository ppa:ondrej/php
apt -y update
apt -y upgrade
# install php-core
apt install php7.4 php7.4-common php7.4-cli
# add all the php extenstions your app needs
apt install php7.4-curl php7.4-json php7.4-gd php7.4-mbstring
apt install php7.4-intl php7.4-bcmath php7.4-bz2 php7.4-xml
apt install php7.4-readline php7.4-zip php7.4-mysql
# I'm using apache prefork MPM, so install it
apt install libapache2-mod-php7.4
a2enmod php7.4
# check version. Success!
php -v
# for good measure, reboot apache
systemctl restart apache2.service
# Finally, purge the old PHP versions
apt purge php7.0 libapache2-mod-php7.0

Finally, run update on more time to get all the latest updates.

apt -y update
apt -y upgrade
apt -y autoremove
apt-get --with-new-pkgs upgrade

AWS CLI V2

How to install AWS CLI version 2.

curl "https://awscli.amazonaws.com/awscli-exe-linux-x86_64.zip" -o "awscliv2.zip"
unzip awscliv2.zip
sudo ./aws/install

Bash Variables

Here’s how to read Bash variables from another file.

Contents of config.sh

#!/bin/bash
var1='thisisvariableone'
var2='thisisvariabletwo'

Call config.sh from another script.

#!/bin/bash
source config.sh
echo var1
echo var2

This is extremely helpful if you have multiple scripts using a common variable. You just to update one file instead of multiple files. All the other scripts will read and pick up the same variables from a config file. You can use this to setup your global variables.

Internet Test

My internet has been flaky lately. I wrote a script that logs my internet connection.

I’m running it in cron every minute.

#!/bin/bash
log='/home/ulysses/Code/spectrum.log'
if nc -zw1 google.com 443;
then 
  echo 'Spectrum is up' $(date) >> $log
else 
  echo 'Spectrum is down' $(date) >> $log
fi

To view, just cat the log.

cat spectrum.log 
Spectrum is up Fri Jun 26 15:14:01 EDT 2020
Spectrum is up Fri Jun 26 15:15:01 EDT 2020
Spectrum is up Fri Jun 26 15:16:01 EDT 2020
Spectrum is up Fri Jun 26 15:17:01 EDT 2020
Spectrum is up Fri Jun 26 15:18:01 EDT 2020

So, I now have a record when it was up or down.

Timedatectl

Here’s another way of setting your server’s timezone. See all the options under North America.

timedatectl list-timezones | grep -i America

Set timezone.

timedatectl set-timezone America/New_York

To check.

date

Restart cron if needed.

systemctl restart cron.service

Largest Files and Directories

Here’s the command to find the largest files and directories in Linux.

du -a /var | sort -n -r | head -n 20

GCP Load Balancer Logging

Go to Logging > Logs Viewer to monitor a GCP Load Balancer.

resource.type="http_load_balancer" AND resource.labels.url_map_name="your-lb" AND resource.labels.project_id="your-project-id"