![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 »NTP Client Configuration on CentOS
Just some quick note on configuring NTP client on CentOS/RHEL/Fedora and forcing time update. Just got tired of having to remember these steps every time I run into NTP.
Searching Log Files
This is a quick example of finding the first and last occurrence of an event in the log file. This can be useful for determining the service outage window and for general troubleshooting. In the example below I am looking at the PostFix maillog file, trying to figure out the duration of the problem I’ve been having with one of the mail relay servers.
Looking for Recently Changed Files
Locating most recently-modified files in the current directory is easy: ls -alt | head. However, searching a directory structure for recent changes may prove a little more challenging. The most common approach is to use …
Installing CentOS 6.x From USB
If at all possible, don’t do it. Find a blank DVD-RW and burn the ISO file. Most current Linux distros can be easily put on a USB stick using freely-available utilities and installed without a hassle. CentOS is not one of them. It would appear, CentOS was designed specifically to make installation from a USB stick a professional challenge for a seasoned sysadmin.
Matching Installed RPMs on Two Systems
The basic problem is this: you have server “A” with a bunch of packages -let’s say PHP-related stuff – installed you need for you application. You need to get the same application working on server “B”, which is not an exact copy of server “A” and is missing some of the packages.
Searching Large Database Tables
Recently I ran into a little problem: I needed to make a simple Web UI allowing users to search a database table containing a copy of the Postfix maillog for quarantined mail addressed to them. …
WordPress Remove Extra Line Breaks
Frequently, imported posts or posts created by auto-blogging plugins will create unnecessary tabs, newlines, and line breaks. This has a negative impact on readability and aesthetics of your site. If you cannot address the problem …
MySQL mysqlhotcopy Script
Here’s a simple script to automate mysqlhotcopy runs from cron to backup multiple MySQL databases. The script loops through the list of databases and kicks off an instance of mysqlhotcopy in the background for each one. Really, …
Monday Rant: HP’s Web Site Fail
Every time I come across a link leading to HP’s angry garden salad of a Web site, I feel as if I stepped in chewing gum. Unfortunately for me, being a sysadmin means I have …
Dynamic Variables in BASH
Assigning variables is easy if you know how many you have and what they are called. The value of a variable can be, well, variable. But the names and number of variables need to be …
VMware vCenter Converter Standalone Notes
The vCenter Standalone Converter is a handy app you can run on your Windows or Linux PC to to P2V a remote server. As convenient as the Converter is, there are a few gotchas that …
Free Rescue CDs for Windows
This is just a quick summary of the more popular rescue CDs out there. All of these are Unix-based bootable ISOs. Some are available as self-burning EXE files, which may be useful if you don’t …
Linux Man Pages (man1)
The current version of manual pages for the most common Linux commands and options. Just for your online convenience.
My Script Won’t Run from Cron!
This is a fairly common issue with running scripts from root cron: the script works perfectly when ran manually from command line, but fails in unexpected ways when running automatically from root cron.
Script to Verify Passwordless SSH Access
If you have passwordless SSH configured on multiple servers, it’s a good idea to verify your access from time to time. This task may get rather tedious with a large number of remote systems. The simple script below will cycle through a list of servers and make sure you can access them without being prompted for a password. Any failures will be saved in the CSV file for later analysis.
Celerra NFS/CIFS Mixed Permissions Mode
This is a quick reminder on how to configure a Celerra filesystem for dual NFS/CIFS access where Windows-side permissions would translate correctly to the NFS side. By default, Celerra datamover will mount filesystems in “Native” mode. In this case, a file or folder created by a Windows user via the CIFS share will take on the default Unix permissions on the NFS side: 755 for folders and 644 for files.
Configure Anonymous FTP on Solaris 10
Below are basic steps for configuring anonymous FTP service on Solaris 10. Use with caution.
Enable Basic FTP Server on Solaris 10
Here are a few simple steps to enable a basic FTP server on Solaris 10.
Simple Network Discovery
The bash script below will scan the specified IP range and use dig and nmap to try to determine the fully-qualified domain name, type and the operating environment of any device that responds to network …
Basic Samba Configuration on Solaris 10
Here’s a sample process for installing and configuring a basic Samba server on Solaris 10.
Solaris 10 NFS Server Configuration
As far as NFS servers go, I think the best platform in terms of performance and stability is Solaris running on SPARC architecture. Perhaps this has something to do with the fact that NFS was created for Solaris. Over the years I’ve been working with NFS servers on AIX, HP-UX, Linux, BSD, etc. It always worked better on Solaris.
RPC: Authentication When Mounting Solaris NFS Share
When mounting an NFS share from a Solaris 10 server, you may encounter the “RPC: Authentication” error. You may notice that you are able to mount the share via NFSv4, not not NFSv3. On the NFS server the /var/adm/messages may show the following errors for the client…
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.
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