![8vl3onvznkopxa6ny9995yrc4gw[1]](https://i0.wp.com/www.krazyworks.com/wp-content/uploads/2021/10/8vl3onvznkopxa6ny9995yrc4gw1-175x150.jpg "Awk & sed Snippets for SysAdmins")
Articles in Data
Create ISO Images
The genisoimage has been around for a few years, but is relatively little-known. It is a pre-mastering program to generate ISO9660/Joliet/HFS hybrid filesystems and is particularly good for creating portable data backups. Here are a …
Removing Metadata from Images
Phones and cameras record a surprising amount of personally-sensitive information with the photos they create. This data includes timestamps, GPS coordinates, software used to process the images and lots of other details you may not …
Extending Swap on LVM2 Logical Volume
To grow swap on LVM you will need to temporarily disable the swap LV. This will leave without swap space, which may upset some applications (Oracle). So the first step should be to set up …
Login Monitor
Sometimes after a couple of beers I start feeling paranoid. I make sure the door is locked and check my firewall logs. Here’s a very basic script to monitor your server’s login record and notify you about …
Ad-Hoc Analysis of /var/log/secure
The /var/log/secure contains a record of authentication and authorization activity on the system. It can be an invaluable resource for the purposes of intrusion detection and prevention. Below are a few simple examples that show how …
Late Night Rant #24: North Korean Internet
Today was the day the North Koreans would have learned they had the Internet and the Americans DDOSed it. Unfortunately, they had no Internet, poor bastards. But, as long as this keeps us entertained… Hey, …
Late Night Rant #23: Kim The Sony-Slayer
Sony execs are shedding crocodile tears over the latest IT security breach that brought substantial financial losses to the company. Let’s not dwell on the trivial: who did it and why are irrelevant technicalities. How …
VSFTPd, SSL, and Firewalls
If you ever wanted to configure SSL/TLS encryption for an FTP server behind a firewall, the “Google wisdom” ranges from “a major pain” to “can’t be done”. Fortunately, things are not all that bad. In …
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 …
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 …
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, …
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 …
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.
Dealing with Full Filesystems
Filled up filesystems is a recurring condition eating up sysadmin time on a regular basis. Some studies show that filesystems running out of space are responsible for most day-to-day issues handled by IT departments. Disk …
Quickly Grow EMC Celerra Filesystem
As we all know, Celerra and its kin can get a bit annoying with their “filesystem over 90%” warning emails. Enabling the “autoextend” feature for the filesystems is one option, but if you are a control …
Secure Data Destruction for Unix
What is secure computer data destruction? Simply put, securely-deleted data cannot be recovered by any known technique. But when it comes to data security, things are rarely simple. New data recovery methods are developed every …
Filesystem Performance Testing Using dd
Below is a simple script to test filesystem read/write performance using dd with varying blocksize parameter. This can be useful for testing local filesystems as well as network-mounted filesystems. The end result will be a …
Quick BTRFS Test on OpenSuse 12.2
The recent announcement from Suse Enterprise Linux that Btrfs was production-ready raised some suspicions. The last time I tested btrfs (not very long ago) the primary issues were excessive CPU utilization and filesystem space that seemed to disappear into nowhere. So, as a quick test, I put together an OpenSuse 12.2 (3.4.6-2.10-desktop, OpenSuse 12.2) 64-bit VM (ESX) with one dual-core vCPUs, 4GB RAM, the OS disk and a 6GB striped LVM filesystem consisting of 4 4-GB virtual disks.
System Recovery: Useful Tools
The following is a brief collection of open-source and/or free tools I regularly use for various system recovery tasks. If the servers you work with have CD drives, I would recommend burning these images onto a CD or DVD. This would save you the trouble of messing with the boot options in the BIOS. More advanced versions of BIOS can mount remote ISO images and boot from those. In most cases, however, this approach requires using the dreaded Internet Explorer an requires Windows.
Searching Large Network-Mounted Filesystems
Recently I ran into a small problem: I needed to find recently-modified files in a very large NFS filesystem. One of the high-level folders contained dozens of sub-folders with thousands of files in each. There is a significant performance penalty associated with placing such directory structures on network-mounted filesystems. Running the “find” command at the top of the filesystem would have taken over an hour and the problem here was not available bandwidth, but the time it takes for the “find” to request and receive attribute information for each folder and file.
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![clfud46mxf2t5zph2l04zlpgl1d[1]](https://i2.wp.com/www.krazyworks.com/wp-content/uploads/2021/08/clfud46mxf2t5zph2l04zlpgl1d1-80x80.jpg "Scraping a Web Page in Bash")
![DSCF5361[1]](https://i1.wp.com/www.krazyworks.com/wp-content/uploads/2020/10/DSCF53611-80x80.jpg "Processing Videos with ffmpeg and Lightroom")
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