How To Obtain a Public Key from an AWS .pem Private Key on Linux and Mac

Author: , February 4th, 2019

Use the ssh-keygen command on a computer to which you’ve downloaded your private key .pem file; for example: First, ensure permissions will allow ssh-keygen to work: chmod 600 /path/to/the/file/your-key-pair.pem Then generate an RSA public key: ssh-keygen -y -f /path/to/the/file/your-key-pair.pem >

How To Test Nagios Remote NRPE Commands

Author: , September 27th, 2018

There are many things to configure in Nagios, especially when using custom check commands. Recently I needed to configure all of the Continuent Clustering Nagios checks. Once setup on the database side, I wanted to confirm that everything was working. Basics: Run a Remote NRPE Check To test a remote NRPE client command from a […]

How To Move Around in Linux CLI Mail

Author: , May 7th, 2018

h Shows you a screenful of message headers (a “header” being the number, sender, date, size and subject). h with no message number shows the current screenful of messages (the number that make up a screenful is set with the screen variable, described below). h$ shows you the last screenful of messages — which is […]

How To get haproxy status via socket using cli

Author: , October 6th, 2017

echo “show stat” | nc -U /var/lib/haproxy/stats | cut -d “,” -f 1,2,5-11,18,24,27,30,36,50,37,56,57,62 | column -s, -t

How To Reduce the Size of a PDF Using Ghostscript

Author: , February 4th, 2017

Make sure you have Ghostscript installed, then: 1 gs -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS="/ebook" -sOutputFile=output.pdf input.pdf gs -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=”/ebook” -sOutputFile=output.pdf input.pdf -dPDFSETTINGS={value} where {value} is one of: /screen – the lowest resolution and lowest file size, fine for viewing on a screen /ebook – mid-range resolution and file size /printer – high-quality […]

How To Send Email From the Command Line on MacOSX 10.10.5 Yosemite

Author: , January 29th, 2017

I wanted to send email from cron for various reasons, but the emails would bounce with an error 554: 554 5.1.8 : Sender address rejected: Domain not found Clearly, Postfix was using the “internal” hostname of myappledesktop.local (MacOSX has TWO hostnames! also, myappledesktop.local is not the real hostname ;-). So, I needed two things: 1. […]

How To Install a .pkg file from the Command Line on MacOSX

Author: , August 12th, 2016

sudo /usr/sbin/installer -pkg /path/to/yourFile.pkg -target /

How To Create a PDF from Multiple Image Files on the Command Line

Author: , June 6th, 2016

convert myFile*.jpg myFile.pdf convert myFile*.png myFile.pdf

How To Install the AWS CLI

Author: , March 29th, 2016 1 2 3 4 5 6 7 8 cd curl "" -o "" unzip yum install python26 /usr/bin/python26 awscli-bundle/install -i /opt/aws/awscli -b /usr/bin/aws aws configure aws s3 ls aws ec2 describe-instances –output text cd curl “” -o “” unzip yum install python26 /usr/bin/python26 awscli-bundle/install -i /opt/aws/awscli -b /usr/bin/aws aws configure aws […]

How To Fix Peer Not Authenticated Errors While Using AWS API Tools

Author: , February 9th, 2016

I was getting the following errors when using an older version of the Amazon EC2 API Tools: $ ec2-describe-regions Unknown problem connecting to host: ‘’ Unable to execute HTTP request: peer not authenticated The solution was to upgrade to the latest AWS CLI tools and start using the aws command instead. For example: aws ec2 […]