Fuzzy Search with Linux

November 25, 2022

This is a quick look at several handy utilities that will allow you to find, navigate, and edit directories and files easily. This overview includes such tools as fzf, rg, fd-find, bat, and the fzf.vim plugin for VIM. The fzf is a general-purpose command-line fuzzy finder. 1. The rg –…Read More

Updating PHP 5.6w to 7.1u on CentOS 6.10

November 22, 2022

Originally published November 23, 2019 @ 11:24 amThis is mostly just a note to self. As I mentioned previously (probably more than once), I very much dislike systemd and will stick with CentOS 6 for as long as possible. Having said that, WordPress dashboard has been nagging me about having…Read More

Analyzing atop Logs with atopsar

November 21, 2022

Originally published November 22, 2019 @ 5:38 pmI have discussed atop previously but concentrated primarily on how to run it and how to collect data. Now I’d like to spend some time talking about ways to analyze the data collected with atop. Included with the atop package is atopsar –…Read More

Sun Juan Mountains, Colorado

November 19, 2022

In July, some friends and I went on an 8,000-mile overlanding trip to Colorado, Utah, Wyoming, and South Dakota. One of the first stops was the Alpine Loop in Colorado’s San Juan mountains. Here are some photos from there and other nearby areas we visited on our first week of…Read More

Appending Filenames

November 16, 2022

Originally published November 17, 2019 @ 11:39 amIf you google how to append, say, current timestamp to the filename in Bash, almost every suggestion boils down to something really basic along the lines of mv $somefile $somefile_$(date +'Y%-%m-%d'). Technically, this is correct and, yet, this is not what was needed.…Read More

Basic Data Recovery in Linux

November 1, 2022

Have you noticed how the letters “e” and “r” are neighbors on your keyboard? And an unrelated question: do you know the difference between crontab -e and crontab -r commands? Look it up if you don’t. Honestly, I’ve never used the crontab -r command in my many years as a…Read More

Renaming Files with exiftool, Part II

October 22, 2022

In the first part of this article, I went over the details of a process for renaming photos to include the geographic location in the filename. Some people asked if the same can be done for videos, and the answer is “probably.” Earlier this year, I went on a month-long…Read More

Dealing with GitHub Desktop

October 14, 2022

GitHub Desktop is one of those terrible applications that I still have to use occasionally, much to my regret. I can’t tell you if a five-year-old or a cat coded it, but this application with relatively straightforward functionality has more bugs than Florida. Sometime in the spring of 2022, GitHub…Read More

Verifying SNMP Connectivity on Multiple Hosts

October 6, 2022

Originally published October 7, 2019 @ 2:42 pmI needed to check if SNMP was accessible on whatever live servers that existed in a particular subnet. Here’s a quick script to do this. You will need to specify subnet information and the SNMP community string. The script will use nmap to…Read More

Selecting Time Ranges from Logs, Part 2

October 3, 2022

Originally published October 4, 2019 @ 3:14 pmA couple of years ago I wrote an article about selecting specific time ranges from log files. I proposed two options: either convert all timestamps to epoch format (a CPU-intensive process) or rely on regex (limited to specific date/time periods). Here’s a followup…Read More

Bulk-Adding IPTables Rules

October 3, 2022

Originally published October 4, 2019 @ 11:58 amI’ve been using my mod of this handy script to block countries with iptables. One issue with the script is that it is adding rules one-by-one using the iptables -A syntax. This is the proper way to add rules, but it does take…Read More

Late Night Rant: Trump, Bolton, Iran, Saudis

September 20, 2022

Originally published September 20, 2019 @ 10:11 pmUsually I try to keep politics out of my blog, but this time I just can’t resist. A few days after Trump fires Bolton for being too tough on Iran (among other reasons), the supposedly Iranian-backed somebodies launched a daring and devastating attack,…Read More

Automatically Block Frequent Visitors

September 19, 2022

Originally published September 20, 2019 @ 8:43 pmI had a few similar scripts floating around this site, but this one is a bit more all-inclusive and better organized. The script will analyze your firewall/whatever access log and block particularly active visitors. I added some extensive (for me, at least) comments…Read More

Windows 10 Upgrades

September 13, 2022

Originally published September 14, 2019 @ 8:56 amI did the only sensible thing and disabled automatic updates on my two Windows 10 laptops. Microsoft’s belated foray into the world of CI/CD for releasing Windows patches suffers from limited automated testing. As you might’ve noticed, the slew of recent defective patches from…Read More

Server and Application Resiliency Testing

September 9, 2022

You are deploying a new application cluster and wonder how it will perform under less-than-ideal conditions: heavy system load, slow storage, network performance degradation. Application resiliency testing is integral to any application architecture but is often passed over because the process is considered overly complex and time-consuming. Here are some…Read More

Detecting Blurry Photos with ImageMagick

September 8, 2022

Originally published September 9, 2019 @ 2:23 amHere’s a typical scenario: I go to a birthday party where everyone knows I’m a shutterbug, so I have to bring my camera. As time goes by and blood alcohol concentration rises and attention to detail declines, the photos become increasingly blurry. The…Read More

Working with iptables Logging

September 1, 2022

Originally published September 2, 2019 @ 6:09 pmMost commonly iptables is used to allow, block, or redirect connections. However, it also has a logging feature that can be very useful for network traffic analysis and system security. In the example below I will get a list of network services listening…Read More

Copying File Attributes Across Servers

August 27, 2022

Originally published August 28, 2019 @ 2:10 pmTo make long story short, had to fix someone’s chmod -R 777 /. A late-night copy-paste fail, it would seem. Needless to say, console access is required, as SSH will not work with permissions on keys wide open. A prerequisite for the process…Read More

CD/DVD-to-ISO Helper Script

August 21, 2022

Originally published August 22, 2019 @ 12:49 pmI can’t recall the last time I needed to convert a CD to ISO. I have four laptops and not one even has a DVD drive. It took me a while to find an external drive and remember how to do this. To…Read More

Longwood Gardens, August 2019

August 18, 2022

Originally published August 19, 2019 @ 12:32 amLongwood Gardens is an American botanical garden. It consists of over 1,077 acres of gardens, woodlands, and meadows in Kennett Square, Pennsylvania, United States in the Brandywine Creek Valley. It is one of the premier horticultural display gardens in the United States and…Read More

Analyzing Network Performance

August 17, 2022

Originally published August 18, 2019 @ 7:09 pmMuch of network performance analysis will be comparative in nature. Thus, seeing the output of multiple commands side by side can be quite useful. Bash has a useful little utility called pr and we’ll make use of it. Side-by-side traceroutes Step 1: create…Read More

Maintaining DNS Records

August 10, 2022

I’ve recently dragged all of my DNS records from Site5. It only took me six years to finally get off that godawful hosting service. In retrospect, keeping a better track of all DNS records would not have wasted time. Then again, I would not be a sysadmin if I wasn’t…Read More

Copying Data in a Restricted Environment

August 8, 2022

Originally published August 9, 2019 @ 8:02 pmConsider this not-so-hypothetical scenario: you have some data on server_a that you would like to copy to server_b. Unfortunately, these two servers cannot communicate with each other. Nor do they have access to any common network-mounted storage. Bummer. I do have a jumpbox…Read More

Raising Dead Services

August 8, 2022

Originally published August 8, 2019 @ 2:22 pmI suppose you may say all of this can be just as easily be done via systemd service config files. Well, yes and no. Yes, it can be done. And, no, not as easily. Not even close. Because systemd sucks by design. But…Read More

Working with ffmpeg on Multi-Core Systems

August 1, 2022

Originally published August 1, 2019 @ 9:25 pmWhile ffmpeg has multithreading capability, getting the best performance on multi-core systems calls for something more than just playing with the -threads option. I’ve seen suggestions to set the -threads option to 1.5 the number of cores, which doesn’t make any sense. The…Read More