![8vl3onvznkopxa6ny9995yrc4gw[1]](https://i0.wp.com/www.krazyworks.com/wp-content/uploads/2021/10/8vl3onvznkopxa6ny9995yrc4gw1-175x150.jpg "Awk & sed Snippets for SysAdmins")
Books have been written on the subject of awk and sed. Here’s a small sample of commands I put together over the years that are useful for everyday system administration tasks. Most of these tasks …
Read the full story »Samba Flexible Character Mapping
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
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.
Recover Crontabs from Log
Some time ago I was using PDSH to update root crontab on a bunch of servers and ran into what looked like a PDSH-specific bug. The same command that worked just fine when executed locally or …
Managing VMs with PowerCLI
Below is a collection of useful Power-CLI one-liners (or thereabouts) that can speed up your script-writing efforts. As everything Windows, things change often and for no obvious reason, so expect to see type is deprecated and …
Sun T-Series ILOM and Solaris 11 Network Configuration
Just some quick notes on setting up Oracle Sun T-series server ILOM and network aggregation with LACP. I don’t get to do this very often, so every time it’s a struggle to remember, with much …
Monitoring DNS Queries
Recently I’ve been decommissioning old DNS servers and those things are notoriously hard to get rid of. The problem was that the IP addresses could not be preserved. I needed to track down every incoming …
DHCP Server Log Analysis
A quick script to go through your DHCP server log and get a summary of MAC addresses and associated DHCP requests. The script will attempt to download the IEEE OUI list for identifying the manufacturers …
Google Search Tips
Google has some advanced search features that few people use, which is a shame. Here are some of them, by Karl Hindle. I am sure there are a few more, but these are the more …
Real-Time Log Stats With Logtop
Logtop is an awesome, albeit a little quirky, real-time log analysis tool developed by Julien Palard. You should use logtop when time is of the essence. When you cannot wait for your cron job to run …
Rsync Time Backup
This is a simple wrapper for the awesome rsync-time-backup script by Laurent Cozic. Through clever use of hard links rsync-time-backup greatly speeds up incremental backups and saves disk space.
Grepping for IPs
This is a small collection of tools and examples for working with IP addresses and ranges in Bash. This post is not meant to be a complete reference, rather a practical how-to guide.
Removing Strings from Binary Log Files
Below is a quick script that will replace specified strings in binary files with random values. A word of caution: the script will preserve the file’s original ctime by briefly changing system time. Obviously, this requires …
Copying a VM between VCenters
I had a little task: clone an operational VM from one VCenter to another. Normally, for such a task I would use the Standalone Converter. Unfortunately, this time I ran into an annoying SSH key …
Watching VSFTP
I have an FTPS server running VSFTP and below is collection of commands useful for monitoring activity and analyzing the logs.
Agedu – Finding Old Files
I almost never delete anything (not on purpose anyway). Having said that, sometimes I do need to find old data on a server and offload it to a NAS. Agedu has been around for ages. …
Monitoring Solr Cores
The Cloud tab of the Solr Web UI is convenient, but not for monitoring purposes. Just like you, I hate XML and parsing it from shell is more convoluted that it needed to be. But …
Tracking Emails in Postfix Logs
Depending on your Postfix configuration, the same email may cycle through the postfix queue several times, changing it’s queue ID and making it difficult to track. For example, if you have Amavis configured for spam and …
Gather MX Records for a List of Domains
This is a simple one: get a list of MX records for the given domains and output into CSV file. Really, the only interesting part of this is the use of array to temporarily store …
Installing Alternative Java Versions on RHEL/CentOS
Below is shorthand for installing alternative versions of Java on your RHEL/CentOS system. This may come in useful for the purposes of testing.
Loan Payment Calculator in Bash
Just a little bit of fun with Bash: a loan payment calculator. Nothing fancy here. Maybe I’ll add the amortization schedule to it later…
Installing NetData on RHEL/CentOS
NetData is a real-time system monitor great for visualizing performance data. Instances of netdata run independently on monitored systems. The results can be accessed remotely and grouped into a single dashboard view, making this tool highly scalable. …
Commands & Shells »
Plundering Facebook Photo Albums
![wyryr1sn52gntzn65v4fpz5lc6v[1]](https://i2.wp.com/www.krazyworks.com/wp-content/uploads/2021/08/wyryr1sn52gntzn65v4fpz5lc6v1-80x80.jpg "Plundering Facebook Photo Albums")
Let’s imagine you need to download all the photos in a Facebook photo album. It can be a public album, a friend’s, or even your own. Sure, you can do this manually, but you probably …
Scraping a Web Page in Bash
![clfud46mxf2t5zph2l04zlpgl1d[1]](https://i2.wp.com/www.krazyworks.com/wp-content/uploads/2021/08/clfud46mxf2t5zph2l04zlpgl1d1-80x80.jpg "Scraping a Web Page in Bash")
Just a scripting exercise because I need to do something important, but I am procrastinating. The idea is simple: grab some URL with text containing somewhat structured data and convert it into a spreadsheet. I …
Applications »
Processing Videos with ffmpeg and Lightroom
![DSCF5361[1]](https://i1.wp.com/www.krazyworks.com/wp-content/uploads/2020/10/DSCF53611-80x80.jpg "Processing Videos with ffmpeg and Lightroom")
On occasion I wondered how to apply advanced photo filters to my lackluster GoPro and drone videos. You know, not the basic exposure/contrast/saturation or the cheesy special effects you find in video editors, but something …
Searching Twitter
![Cat-Devouring-A-Bird-Pablo-Picasso[1]](https://i0.wp.com/www.krazyworks.com/wp-content/uploads/2020/10/Cat-Devouring-A-Bird-Pablo-Picasso1-80x80.jpg "Searching Twitter")
Here are just a few hopefully useful tips for searching Twitter to get more relevant results and buy cheap twitter followers.
Data »
Scraping a Web Page in Bash
Just a scripting exercise because I need to do something important, but I am procrastinating. The idea is simple: grab some URL with text containing somewhat structured data and convert it into a spreadsheet. I …
Generating Random Text Files for Testing
![91ebozy1e3b138waujy28agrngy[1]](https://i2.wp.com/www.krazyworks.com/wp-content/uploads/2021/08/91ebozy1e3b138waujy28agrngy1-80x80.jpg "Generating Random Text Files for Testing")
Sometimes you need dummy folder structures populated with random data for testing your various scripts and processes – backups, file transfers, encryption, compression, etc. Every time I need something like this, I end up writing …
Monitoring »
Finding Cron Jobs
![iwoau71okwxqh4jv3k4ook32qps[1]](https://i2.wp.com/www.krazyworks.com/wp-content/uploads/2021/08/iwoau71okwxqh4jv3k4ook32qps1-80x80.jpg "Finding Cron Jobs")
Cron is an indispensable tool for system administration. The difficulties in working with cron in a large environment stem from its decentralized nature. Cron jobs multiply like rabbits, and keeping track of them is not …
Understanding Memory Utilization in Linux
![5gtysva4wkc8mzc1k3e66vaycxx[1]](https://i1.wp.com/www.krazyworks.com/wp-content/uploads/2021/08/5gtysva4wkc8mzc1k3e66vaycxx1-80x80.jpg "Understanding Memory Utilization in Linux")
This is a depressing – and all-too-common – scenario: a user runs the free command and opens a support case because he sees zero “free” memory on the server.
Networking »
Validating HTTPS Cache Peers for Squid
![sy2zeb1vp2h8itlxfbbylw0jrm0[1]](https://i0.wp.com/www.krazyworks.com/wp-content/uploads/2019/12/sy2zeb1vp2h8itlxfbbylw0jrm01-80x80.jpg "Validating HTTPS Cache Peers for Squid")
I have a squid proxy server that uses a long list of authenticated cache peers in a round-robin configuration. The process looks something like this:
Verifying SNMP Connectivity on Multiple Hosts
![Photo-2019-10-07-14-39-03_0266[1]](https://i1.wp.com/www.krazyworks.com/wp-content/uploads/2019/11/Photo-2019-10-07-14-39-03_02661-80x80.jpg "Verifying SNMP Connectivity on Multiple Hosts")
I 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.
Editor
Igor
Sr. Unix SysAdmin with twenty years experience supporting Solaris, HP-UX, AIX, IRIX, and Linux servers in a large distributed environment.
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