![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 »Identifying Available IPs on the Network
At some point available IPs on your network may become few and hard to come by. Documentation becomes outdated and does not accurately reflect which IPs are still in use. A good starting point would …
Multithreaded Encryption and Compression
One problem with encryption is it’s a slow and resource-intensive process. While most encryption software lacks multithreading support, it is possible to use the GNU Parallel to take full advantage of modern multi-core CPUs to …
Using truss and nawk to Trace Solaris Processes
Here’s the problem I ran into today on a Solaris 11 SPARC server: an application UI would occasionally freeze for a few second when executing a particular function. Nobody could quite figure out where the …
Filesystem Syncronization with Lsyncd
Lsyncd monitors a local filesystem for changes and mirrors those changes to a filesystem on a remote server. The advantage of lsyncd over rsync is the former’s ability to detect filesystem changes without having to re-scan …
Toilet Fun
It’s been a slow Friday afternoon at the office, so I decided to pimp my VM. The tool of choice is “toilet“. Depending on your flavor, this may or may not be easy to install. …
Resizing Hitachi VSP LDEVs (LUNs)
Resizing Hitachi VSP LUNs (aka LDEVs) is a quick and simple task. Unfortunately, due to Hitachi Storage Navigator’s archaic design, the LDEV resize function, while easy to use, is not easy to find. So, here’s …
Adding Swap with Solaris 11 ZFS
With the swap partition residing on a ZFS filesystem, you have an easy way of adding swap on the fly. Reducing swap is not quite so simple, but we’l talk about that later. To check …
Rescanning New LUNs on VNX
Just a quick background of the little problem I ran into with our VNX: after creating a couple of LUNs for the mapped file pool using Unisphere, I clicked “Rescan Storage Systems” and got “This …
Enable NTP Client on Solaris 11
Just some quick instructions for configuring and enabling NTP client on Solaris 11.
Remove Duplicate IPTables Rules
Duplicate entries may appear in your iptables configuration due to parallel efforts of various network security-related applications that may be running on your server. In most cases, having duplicate iptables rules is no big deal, …
Block WordPress Attackers With IPTables
After installing LogStash, I noticed server load went from around 1.2 to 50+. This was cause by a brute-force attack against WordPress wp-login.php from some IP in France (of all places). While LogStash should not …
Patching Binary Files in Bash
Just the other day I ran into a particularly annoying issue: after an application upgrade, all printed documents had “<<bbj>>~D” on the first line. The application sends EPS files to the CUPS print server. For whatever reason, …
CUPS Printing to a File
Using CUPS to print to a file instead of an actual printer is a great idea for troubleshooting and archiving purposes. This saves trees but, most importantly, saves you the walk to the printer. So, how …
PHP Unable to allocate memory for pool
The following error may be found in /var/log/httpd/${domain}/error_log when APC memory is set too low: “PHP Warning: require_once(): Unable to allocate memory for pool”. APC is Alternative PHP Cache. You can check the version of …
Getting Epoch Time on Solaris 10 and Older
You can get the epoch time on Solaris 11 and Linux simply by running the date command:
Quick Setup of Salt on CentOS/RHEL
Just some quick notes on installing and configuring Salt master server and minions to run remote commands for various sysamdin needs.
Searching Files for Text Strings
In the past, I’ve posted a couple of versions of this script in Bash and Korn shell. Here’s a much-expanded and improved Bash version. The script will take your input and look for files containing …
Recovering Deleted /bin on CentOS
So, as the saying goes, shit happens and the other day I accidentally deleted /boot on a CentOS 6 box. I have NetBackup running on the system, so this would not have been a problem …
Disable Formatting When Pasting into Outlook
By default, Outlook will preserve source text formatting during copy/paste operations. At times this can be very annoying, especially when composing emails of technical nature. There’s a good chance your email will end up looking …
Installing GoAccess on CentOS/RHEL
GoAccess is a simple but useful “top”-like CLI utility giving you a quick overview of the Apache access_log entries.
What To Do When Windows Ignores SD Card
Here’s a common scenario: you insert or swap and SD card in your laptop and… nothing happens. Sometimes Windows decides to ignore the SD card for reasons unknown (well, the true reason is it’s Windows). …
Permanently Ban IP with Fail2Ban
If you’re not familiar with Fail2Ban: it’s a log analysis tool that detects failed login attempts for your SSH, FTP, etc services and uses IPTools firewall to temporarily drop connection requests from the offending IP addresses. …
Commands & Shells »
Synology NAS Hacks
![rhd3hj6zvnqeth7qo8em0alduj0[1]](https://i2.wp.com/www.krazyworks.com/wp-content/uploads/2021/10/rhd3hj6zvnqeth7qo8em0alduj01-80x80.jpg "Synology NAS Hacks")
I’ve been using various Synology NAS devices for many years now, and they’re great. Well, almost. There are a few rough spots that don’t thrill me. These consumer-grade devices are designed to be difficult to …
Finding Duplicate Photos
![9dwz62kvm0gtjya9kwb7pawtk9y[1]](https://i2.wp.com/www.krazyworks.com/wp-content/uploads/2021/10/9dwz62kvm0gtjya9kwb7pawtk9y1-80x80.jpg "Finding Duplicate Photos")
Being a shutterbug and a digital hoarder can get expensive. A couple of days ago, my
TerraMaster D5-300 5-bay DAS crashed. Again. This time it was the power supply. I replaced it only to discover that …
Applications »
Synology NAS Hacks
I’ve been using various Synology NAS devices for many years now, and they’re great. Well, almost. There are a few rough spots that don’t thrill me. These consumer-grade devices are designed to be difficult to …
WordPress: Post-processing of the image failed
![ytioq398kc1wnvvz95uixhcn5ii[1]](https://i2.wp.com/www.krazyworks.com/wp-content/uploads/2021/08/ytioq398kc1wnvvz95uixhcn5ii1-80x80.jpg "WordPress: Post-processing of the image failed")
This particular WordPress issue appeared with version 5.3 and is refusing to go away. However, the problem here is not with WordPress but with the Apache ModSecurity. The particular ModSecurity rule in question is 200003 …
Data »
Synology NAS Hacks
I’ve been using various Synology NAS devices for many years now, and they’re great. Well, almost. There are a few rough spots that don’t thrill me. These consumer-grade devices are designed to be difficult to …
Finding Duplicate Photos
Being a shutterbug and a digital hoarder can get expensive. A couple of days ago, my
TerraMaster D5-300 5-bay DAS crashed. Again. This time it was the power supply. I replaced it only to discover that …
Monitoring »
NFS I/O Stats with Logging
![tq9mhhd5xy2q0kto2j1785n6odv[1]](https://i1.wp.com/www.krazyworks.com/wp-content/uploads/2021/10/tq9mhhd5xy2q0kto2j1785n6odv1-80x80.jpg "NFS I/O Stats with Logging")
The nfsiostat is an excellent tool for analyzing NFS performance. The only major problem with this utility is that it’s designed to be used interactively. It does not have logging or timestamping capabilities. I needed …
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 …
Networking »
NFS I/O Stats with Logging
The nfsiostat is an excellent tool for analyzing NFS performance. The only major problem with this utility is that it’s designed to be used interactively. It does not have logging or timestamping capabilities. I needed …
Inventorying NFS Mounts and Mount Options
![4ucne6vs8m7hqdl0el9ddqd1sql[1]](https://i2.wp.com/www.krazyworks.com/wp-content/uploads/2021/10/4ucne6vs8m7hqdl0el9ddqd1sql1-80x80.jpg "Inventorying NFS Mounts and Mount Options")
As time goes by, NFS mounts multiply like rabbits. Added by many different people over the years, these entries present a dizzying variety of mount options – most are a copy-paste job that makes little …
Editor
Igor
Sr. Unix SysAdmin with twenty years experience supporting Solaris, HP-UX, AIX, IRIX, and Linux servers in a large distributed environment.
Latest Comments