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AWS CLI Cheat Sheet

August 14, 2018 – 4:18 pm

The installation and configuration process for AWS CLI is fairly simple. The package itself is installed with pip (yum -y install python-pip):

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Networking

Unix and Linux network configuration. Multiple network interfaces. Bridged NICs. High-availability network configurations.

Applications

Reviews of latest Unix and Linux software. Helpful tips for application support admins. Automating application support.

Data

Disk partitioning, filesystems, directories, and files. Volume management, logical volumes, HA filesystems. Backups and disaster recovery.

Monitoring

Distributed server monitoring. Server performance and capacity planning. Monitoring applications, network status and user activity.

Commands & Shells

Cool Unix shell commands and options. Command-line tools and application. Things every Unix sysadmin needs to know.

Commands & Shells »

Deleting Hidden Files

August 7, 2018 – 4:14 pm
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This simplest of problems just never fails to find a new victim. For whatever reason you want to delete all hidden files in the current directory and subfolders. Without much thinking you just type rm -rf .* Here’s a classic example of one developer giving another developer a terrile advise. Read the full story »

Quickly Grow tmpfs filesystem

August 6, 2018 – 4:13 pm
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Just a quick command to double the size of the /tmp filesystem that uses tmpfs. This is  for those situations when you can’t be bothered to think.

Duck Duck Go Search from Shell

August 5, 2018 – 4:10 pm
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The ddgr python script is a command line interface for Duck Duck Go  – a privacy-oriented search engine that, unlike Google, will not give away your data to the likes of Cambridge Analytica. In the …

Obfuscating Shell Scripts

August 1, 2018 – 4:04 pm
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Unix shell scripting language is run by the command-line interpreter and, as such, can be read and understood by anyone with sufficient access and experience. Sometimes this is not a good thing. Sometimes you want …

The Mystery of a Hemisphere

July 31, 2018 – 4:00 pm
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To make this long (and embarrassing) story short: a friend’s kid had a homework assignment in geometry to calculate the surface area of a conjoined cone, a cylinder, and a hemisphere.

Raspbian ‘partitions on different devices’ Error

July 30, 2018 – 3:59 pm
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After downloading a Raspbian image and writing it to an SD card, you get the following error when trying to boot the Pi: “Could not expand filesystem, please try raspi-config or rc_gui. Boot and root …

Tmux Bootstrap Configuration

February 17, 2018 – 3:22 pm
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Just a list of commands to quickly configure tmux with some of the best (i.e. my favorite) plugins and options. Feel free to disagree – you may be right – but I don’t think so.

Find Large Files

February 17, 2018 – 3:21 pm
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Every time a filesystem is running out of space and I need to find something to delete, I end up googling the syntax for the find command to make sure it stays off NFS and …

Show Logged In Users During a Time Window

February 17, 2018 – 2:59 pm
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Let’s say you want to see who was logged in on the server during last weekend. This includes users who, say, logged in on Thursday and haven’t logged out until Saturday afternoon.

Extracting Email Addresses from TCP Streams

December 5, 2017 – 7:06 pm
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Here’s a quick example of using tshark to extract email addresses from TCP streams. Let’s say some application on your server is sending emails and you want to find out who is receiving those emails.

Export WP Posts and Sync to Sharepoint

November 14, 2017 – 12:24 pm
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Long story short: old wiki is overloaded and broken; new wiki is not a wiki but SharePoint – a glorified file server; people are forced to improvise and put documentation on a WP wiki; bosses …

Useful MySQL One-Liners

November 8, 2017 – 12:16 pm
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I am by no means an expert SQL programmer. Having said that, I’ve been using MySQL for a very long time. This is a collection of simple but useful SQL queries and MySQL configuration options. …

Plotting Log Data

August 9, 2017 – 10:13 pm
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While I am on the subject of selecting time ranges from logs, a practical application presented itself. A lonely server in a far-away land with a habit of running out of memory could only be …

Croncal – the Cron Calendar

August 9, 2017 – 10:52 am
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The croncal is a clever Perl script that reads entries in your crontab and outputs a schedule, showing the time when cron jobs will run.

Install and Configure Etckeeper

June 23, 2017 – 8:05 am
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Etckeeper is a handy tool that uses git to keep track of changes to anything in /etc (or any other folder you choose). It’s very simple to use and can help you quickly identify and undo stupid …

Using IPTables to Allow Access to Private Networks

June 22, 2017 – 9:46 am
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Below is a quick example of how to use iptables to allow port access for all types of private networks. In this case we’re allowing access to ports 10000 and 20000, commonly used by webmin and usermin.

Get a List of all ESX Hosts in a Datacenter

April 17, 2017 – 3:18 pm
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Another simple one-liner to get a list of hostnames of all ESX servers in the vCenter. This can be useful for a number of things, specifically as input for other PowerCLI scripts.

Use PowerCLI to Change NIC Type

April 17, 2017 – 11:52 am
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This is a quick PowerCLI script that reads from a list of VM names and for each VM with network adapter type “E1000” changes it to “Vmxnet3”. Nothing fancy, no reboot is needed. MAC should …

Pushing SSH Keys

March 21, 2017 – 10:54 am
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This is just a quick note for me on pushing SSH keys using sshpass and xargs. The ~/hosts.txt file contains a list of remote hosts, one per line. And the ~/.passwd.txt contains your password. Make sure to chmod 400 …

Configure and Run esxcli on Red Hat

March 20, 2017 – 3:58 pm
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The esxcli utility is used to interface with the vSphere and ESX hosts. It is a useful tool for getting to some basic VMWare functionality from Unix shell. It is also a pre-requisite for some of …

Wget Examples

March 1, 2017 – 9:25 pm
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This is a follow-up to my previous wget notes (1, 2, 3, 4). From time to time I find myself googling wget syntax even though I think I’ve used every option of this excellent utility over the …

Samba Flexible Character Mapping

March 1, 2017 – 6:33 pm
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This is probably old news to most of you, but I just found out: Samba v 3.5+ has a new option for flexible mapping of filename characters. Unix filenames allow certain characters that Windows filename …

Install Webmin on CentOS and Redhat

February 27, 2017 – 2:10 pm
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Just a quick short-hand to installing Webmin on CentOS/RHEL. The latest Webmin version comes with a cool new interface theme. You should check it out.